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author | Rong-En Fan <rafan@FreeBSD.org> | 2008-11-09 09:06:04 +0000 |
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committer | Rong-En Fan <rafan@FreeBSD.org> | 2008-11-09 09:06:04 +0000 |
commit | a388f199193767bacbb38b172ab89cb84369736c (patch) | |
tree | a1816f5667d2280b970ca44e407bac8cc4496c0a /doc/html | |
parent | aa59d4d4c5dda7e1c6f9dc0cc6edc58992a525c7 (diff) | |
download | src-a388f199193767bacbb38b172ab89cb84369736c.tar.gz src-a388f199193767bacbb38b172ab89cb84369736c.zip |
- Flatten the vendor area
Notes
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svn path=/vendor/ncurses/dist/; revision=184786
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diff --git a/doc/html/NCURSES-Programming-HOWTO.html b/doc/html/NCURSES-Programming-HOWTO.html new file mode 100644 index 000000000000..3a1010635ff0 --- /dev/null +++ b/doc/html/NCURSES-Programming-HOWTO.html @@ -0,0 +1,6413 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html> +<head> +<meta name="generator" content= +"HTML Tidy for Linux/x86 (vers 1st December 2004), see www.w3.org"> +<title>NCURSES Programming HOWTO</title> +<meta name="GENERATOR" content= +"Modular DocBook HTML Stylesheet Version 1.7"> +</head> +<body class="ARTICLE" bgcolor="#FFFFFF" text="#000000" link= +"#0000FF" vlink="#840084" alink="#0000FF"> +<div class="ARTICLE"> +<div class="TITLEPAGE"> +<h1 class="TITLE"><a name="AEN2" id="AEN2">NCURSES Programming +HOWTO</a></h1> +<h3 class="AUTHOR"><a name="AEN4" id="AEN4">Pradeep Padala</a></h3> +<div class="AFFILIATION"> +<div class="ADDRESS"> +<p class="ADDRESS"><code class="EMAIL"><<a href= +"mailto:ppadala@gmail.com">ppadala@gmail.com</a>></code></p> +</div> +</div> +<p class="PUBDATE">v1.9, 2005-06-20<br></p> +<div class="REVHISTORY"> +<table width="100%" border="0"> +<tr> +<th align="left" valign="top" colspan="3"><b>Revision +History</b></th> +</tr> +<tr> +<td align="left">Revision 1.9</td> +<td align="left">2005-06-20</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">The license has been changed to the +MIT-style license used by NCURSES. Note that the programs are also +re-licensed under this.</td> +</tr> +<tr> +<td align="left">Revision 1.8</td> +<td align="left">2005-06-17</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Lots of updates. Added references and +perl examples. Changes to examples. Many grammatical and stylistic +changes to the content. Changes to NCURSES history.</td> +</tr> +<tr> +<td align="left">Revision 1.7.1</td> +<td align="left">2002-06-25</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Added a README file for building and +instructions for building from source.</td> +</tr> +<tr> +<td align="left">Revision 1.7</td> +<td align="left">2002-06-25</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Added "Other formats" section and made +a lot of fancy changes to the programs. Inlining of programs is +gone.</td> +</tr> +<tr> +<td align="left">Revision 1.6.1</td> +<td align="left">2002-02-24</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Removed the old Changelog section, +cleaned the makefiles</td> +</tr> +<tr> +<td align="left">Revision 1.6</td> +<td align="left">2002-02-16</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Corrected a lot of spelling mistakes, +added ACS variables section</td> +</tr> +<tr> +<td align="left">Revision 1.5</td> +<td align="left">2002-01-05</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Changed structure to present proper +TOC</td> +</tr> +<tr> +<td align="left">Revision 1.3.1</td> +<td align="left">2001-07-26</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Corrected maintainers paragraph, +Corrected stable release number</td> +</tr> +<tr> +<td align="left">Revision 1.3</td> +<td align="left">2001-07-24</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Added copyright notices to main +document (LDP license) and programs (GPL), Corrected +printw_example.</td> +</tr> +<tr> +<td align="left">Revision 1.2</td> +<td align="left">2001-06-05</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Incorporated ravi's changes. Mainly to +introduction, menu, form, justforfun sections</td> +</tr> +<tr> +<td align="left">Revision 1.1</td> +<td align="left">2001-05-22</td> +<td align="left">Revised by: ppadala</td> +</tr> +<tr> +<td align="left" colspan="3">Added "a word about window" section, +Added scanw_example.</td> +</tr> +</table> +</div> +<div> +<div class="ABSTRACT"><a name="AEN67" id="AEN67"></a> +<p><em>This document is intended to be an "All in One" guide for +programming with ncurses and its sister libraries. We graduate from +a simple "Hello World" program to more complex form manipulation. +No prior experience in ncurses is assumed. Send comments to +<a href="mailto:ppadala@gmail.com" target="_top">this +address</a></em></p> +</div> +</div> +<hr></div> +<div class="TOC"> +<dl> +<dt><b>Table of Contents</b></dt> +<dt>1. <a href="#INTRO">Introduction</a></dt> +<dd> +<dl> +<dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt> +<dt>1.2. <a href="#WHATCANWEDO">What we can do with +NCURSES</a></dt> +<dt>1.3. <a href="#WHERETOGETIT">Where to get it</a></dt> +<dt>1.4. <a href="#PURPOSE">Purpose/Scope of the document</a></dt> +<dt>1.5. <a href="#ABOUTPROGRAMS">About the Programs</a></dt> +<dt>1.6. <a href="#OTHERFORMATS">Other Formats of the +document</a></dt> +<dt>1.7. <a href="#CREDITS">Credits</a></dt> +<dt>1.8. <a href="#WISHLIST">Wish List</a></dt> +<dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt> +</dl> +</dd> +<dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt> +<dd> +<dl> +<dt>2.1. <a href="#COMPILECURSES">Compiling With the NCURSES +Library</a></dt> +<dt>2.2. <a href="#DISSECTION">Dissection</a></dt> +</dl> +</dd> +<dt>3. <a href="#GORY">The Gory Details</a></dt> +<dt>4. <a href="#INIT">Initialization</a></dt> +<dd> +<dl> +<dt>4.1. <a href="#ABOUTINIT">Initialization functions</a></dt> +<dt>4.2. <a href="#RAWCBREAK">raw() and cbreak()</a></dt> +<dt>4.3. <a href="#ECHONOECHO">echo() and noecho()</a></dt> +<dt>4.4. <a href="#KEYPAD">keypad()</a></dt> +<dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt> +<dt>4.6. <a href="#MISCINIT">Miscellaneous Initialization +functions</a></dt> +<dt>4.7. <a href="#INITEX">An Example</a></dt> +</dl> +</dd> +<dt>5. <a href="#AWORDWINDOWS">A Word about Windows</a></dt> +<dt>6. <a href="#PRINTW">Output functions</a></dt> +<dd> +<dl> +<dt>6.1. <a href="#ADDCHCLASS">addch() class of functions</a></dt> +<dt>6.2. <a href="#AEN298">mvaddch(), waddch() and +mvwaddch()</a></dt> +<dt>6.3. <a href="#PRINTWCLASS">printw() class of +functions</a></dt> +<dt>6.4. <a href="#ADDSTRCLASS">addstr() class of +functions</a></dt> +<dt>6.5. <a href="#ACAUTION">A word of caution</a></dt> +</dl> +</dd> +<dt>7. <a href="#SCANW">Input functions</a></dt> +<dd> +<dl> +<dt>7.1. <a href="#GETCHCLASS">getch() class of functions</a></dt> +<dt>7.2. <a href="#SCANWCLASS">scanw() class of functions</a></dt> +<dt>7.3. <a href="#GETSTRCLASS">getstr() class of +functions</a></dt> +<dt>7.4. <a href="#GETSTREX">Some examples</a></dt> +</dl> +</dd> +<dt>8. <a href="#ATTRIB">Attributes</a></dt> +<dd> +<dl> +<dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt> +<dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs attrset()</a></dt> +<dt>8.3. <a href="#ATTR_GET">attr_get()</a></dt> +<dt>8.4. <a href="#ATTR_FUNCS">attr_ functions</a></dt> +<dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt> +<dt>8.6. <a href="#CHGAT">chgat() functions</a></dt> +</dl> +</dd> +<dt>9. <a href="#WINDOWS">Windows</a></dt> +<dd> +<dl> +<dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt> +<dt>9.2. <a href="#LETBEWINDOW">Let there be a Window !!!</a></dt> +<dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt> +<dt>9.4. <a href="#OTHERSTUFF">The other stuff in the +example</a></dt> +<dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border +functions</a></dt> +</dl> +</dd> +<dt>10. <a href="#COLOR">Colors</a></dt> +<dd> +<dl> +<dt>10.1. <a href="#COLORBASICS">The basics</a></dt> +<dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color +Definitions</a></dt> +<dt>10.3. <a href="#COLORCONTENT">Color Content</a></dt> +</dl> +</dd> +<dt>11. <a href="#KEYS">Interfacing with the key board</a></dt> +<dd> +<dl> +<dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt> +<dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage +example</a></dt> +</dl> +</dd> +<dt>12. <a href="#MOUSE">Interfacing with the mouse</a></dt> +<dd> +<dl> +<dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt> +<dt>12.2. <a href="#GETTINGEVENTS">Getting the events</a></dt> +<dt>12.3. <a href="#MOUSETOGETHER">Putting it all Together</a></dt> +<dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous +Functions</a></dt> +</dl> +</dd> +<dt>13. <a href="#SCREEN">Screen Manipulation</a></dt> +<dd> +<dl> +<dt>13.1. <a href="#GETYX">getyx() functions</a></dt> +<dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt> +<dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt> +</dl> +</dd> +<dt>14. <a href="#MISC">Miscellaneous features</a></dt> +<dd> +<dl> +<dt>14.1. <a href="#CURSSET">curs_set()</a></dt> +<dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving Curses +mode</a></dt> +<dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt> +</dl> +</dd> +<dt>15. <a href="#OTHERLIB">Other libraries</a></dt> +<dt>16. <a href="#PANELS">Panel Library</a></dt> +<dd> +<dl> +<dt>16.1. <a href="#PANELBASICS">The Basics</a></dt> +<dt>16.2. <a href="#COMPILEPANELS">Compiling With the Panels +Library</a></dt> +<dt>16.3. <a href="#PANELBROWSING">Panel Window Browsing</a></dt> +<dt>16.4. <a href="#USERPTRUSING">Using User Pointers</a></dt> +<dt>16.5. <a href="#PANELMOVERESIZE">Moving and Resizing +Panels</a></dt> +<dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing +Panels</a></dt> +<dt>16.7. <a href="#PANELABOVE">panel_above() and panel_below() +Functions</a></dt> +</dl> +</dd> +<dt>17. <a href="#MENUS">Menus Library</a></dt> +<dd> +<dl> +<dt>17.1. <a href="#MENUBASICS">The Basics</a></dt> +<dt>17.2. <a href="#COMPILEMENUS">Compiling With the Menu +Library</a></dt> +<dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work horse of the +menu system</a></dt> +<dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt> +<dt>17.5. <a href="#SCROLLMENUS">Scrolling Menus</a></dt> +<dt>17.6. <a href="#MULTICOLUMN">Multi Columnar Menus</a></dt> +<dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued Menus</a></dt> +<dt>17.8. <a href="#MENUOPT">Menu Options</a></dt> +<dt>17.9. <a href="#MENUUSERPTR">The useful User Pointer</a></dt> +</dl> +</dd> +<dt>18. <a href="#FORMS">Forms Library</a></dt> +<dd> +<dl> +<dt>18.1. <a href="#FORMBASICS">The Basics</a></dt> +<dt>18.2. <a href="#COMPILEFORMS">Compiling With the Forms +Library</a></dt> +<dt>18.3. <a href="#PLAYFIELDS">Playing with Fields</a></dt> +<dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt> +<dt>18.5. <a href="#FILEDVALIDATE">Field Validation</a></dt> +<dt>18.6. <a href="#FORMDRIVER">Form Driver: The work horse of the +forms system</a></dt> +</dl> +</dd> +<dt>19. <a href="#TOOLS">Tools and Widget Libraries</a></dt> +<dd> +<dl> +<dt>19.1. <a href="#CDK">CDK (Curses Development Kit)</a></dt> +<dt>19.2. <a href="#DIALOG">The dialog</a></dt> +<dt>19.3. <a href="#PERLCURSES">Perl Curses Modules CURSES::FORM +and CURSES::WIDGETS</a></dt> +</dl> +</dd> +<dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt> +<dd> +<dl> +<dt>20.1. <a href="#GAMEOFLIFE">The Game of Life</a></dt> +<dt>20.2. <a href="#MAGIC">Magic Square</a></dt> +<dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt> +<dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt> +<dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt> +<dt>20.6. <a href="#TT">Typing Tutor</a></dt> +</dl> +</dd> +<dt>21. <a href="#REF">References</a></dt> +</dl> +</div> +<div class="SECT1"> +<h2 class="SECT1"><a name="INTRO" id="INTRO">1. +Introduction</a></h2> +<p>In the olden days of teletype terminals, terminals were away +from computers and were connected to them through serial cables. +The terminals could be configured by sending a series of bytes. All +the capabilities (such as moving the cursor to a new location, +erasing part of the screen, scrolling the screen, changing modes +etc.) of terminals could be accessed through these series of bytes. +These control seeuqnces are usually called escape sequences, +because they start with an escape(0x1B) character. Even today, with +proper emulation, we can send escape sequences to the emulator and +achieve the same effect on a terminal window.</p> +<p>Suppose you wanted to print a line in color. Try typing this on +your console.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000">echo "^[[0;31;40mIn Color"</font> +</pre></td> +</tr> +</table> +<p>The first character is an escape character, which looks like two +characters ^ and [. To be able to print it, you have to press +CTRL+V and then the ESC key. All the others are normal printable +characters. You should be able to see the string "In Color" in red. +It stays that way and to revert back to the original mode type +this.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000">echo "^[[0;37;40m"</font> +</pre></td> +</tr> +</table> +<p>Now, what do these magic characters mean? Difficult to +comprehend? They might even be different for different terminals. +So the designers of UNIX invented a mechanism named <var class= +"LITERAL">termcap</var>. It is a file that lists all the +capabilities of a particular terminal, along with the escape +sequences needed to achieve a particular effect. In the later +years, this was replaced by <var class="LITERAL">terminfo</var>. +Without delving too much into details, this mechanism allows +application programs to query the terminfo database and obtain the +control characters to be sent to a terminal or terminal +emulator.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is +NCURSES?</a></h3> +<p>You might be wondering, what the import of all this technical +gibberish is. In the above scenario, every application program is +supposed to query the terminfo and perform the necessary stuff +(sending control characters etc.). It soon became difficult to +manage this complexity and this gave birth to 'CURSES'. Curses is a +pun on the name "cursor optimization". The Curses library forms a +wrapper over working with raw terminal codes, and provides highly +flexible and efficient API (Application Programming Interface). It +provides functions to move the cursor, create windows, produce +colors, play with mouse etc. The application programs need not +worry about the underlying terminal capabilities.</p> +<p>So what is NCURSES? NCURSES is a clone of the original System V +Release 4.0 (SVr4) curses. It is a freely distributable library, +fully compatible with older version of curses. In short, it is a +library of functions that manages an application's display on +character-cell terminals. In the remainder of the document, the +terms curses and ncurses are used interchangeably.</p> +<p>A detailed history of NCURSES can be found in the NEWS file from +the source distribution. The current package is maintained by +<a href="mailto:dickey@his.com" target="_top">Thomas Dickey</a>. +You can contact the maintainers at <a href= +"mailto:bug-ncurses@gnu.org" target= +"_top">bug-ncurses@gnu.org</a>.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WHATCANWEDO" id="WHATCANWEDO">1.2. What +we can do with NCURSES</a></h3> +<p>NCURSES not only creates a wrapper over terminal capabilities, +but also gives a robust framework to create nice looking UI (User +Interface)s in text mode. It provides functions to create windows +etc. Its sister libraries panel, menu and form provide an extension +to the basic curses library. These libraries usually come along +with curses. One can create applications that contain multiple +windows, menus, panels and forms. Windows can be managed +independently, can provide 'scrollability' and even can be +hidden.</p> +<p>Menus provide the user with an easy command selection option. +Forms allow the creation of easy-to-use data entry and display +windows. Panels extend the capabilities of ncurses to deal with +overlapping and stacked windows.</p> +<p>These are just some of the basic things we can do with ncurses. +As we move along, We will see all the capabilities of these +libraries.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WHERETOGETIT" id="WHERETOGETIT">1.3. +Where to get it</a></h3> +<p>All right, now that you know what you can do with ncurses, you +must be rearing to get started. NCURSES is usually shipped with +your installation. In case you don't have the library or want to +compile it on your own, read on.</p> +<p><em>Compiling the package</em></p> +<p>NCURSES can be obtained from <a href= +"ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target= +"_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a> or any +of the ftp sites mentioned in <a href= +"http://www.gnu.org/order/ftp.html" target= +"_top">http://www.gnu.org/order/ftp.html</a>.</p> +<p>Read the README and INSTALL files for details on to how to +install it. It usually involves the following operations.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> tar zxvf ncurses<version>.tar.gz # unzip and untar the archive + cd ncurses<version> # cd to the directory + ./configure # configure the build according to your + # environment + make # make it + su root # become root + make install # install it</font> +</pre></td> +</tr> +</table> +<p><em>Using the RPM</em></p> +<p>NCURSES RPM can be found and downloaded from <a href= +"http://rpmfind.net" target="_top">http://rpmfind.net</a> . The RPM +can be installed with the following command after becoming +root.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> rpm -i <downloaded rpm></font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4. Purpose/Scope +of the document</a></h3> +<p>This document is intended to be a "All in One" guide for +programming with ncurses and its sister libraries. We graduate from +a simple "Hello World" program to more complex form manipulation. +No prior experience in ncurses is assumed. The writing is informal, +but a lot of detail is provided for each of the examples.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ABOUTPROGRAMS" id="ABOUTPROGRAMS">1.5. +About the Programs</a></h3> +<p>All the programs in the document are available in zipped form +<a href= +"http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz" +target="_top">here</a>. Unzip and untar it. The directory structure +looks like this.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000">ncurses + | + |----> JustForFun -- just for fun programs + |----> basics -- basic programs + |----> demo -- output files go into this directory after make + | | + | |----> exe -- exe files of all example programs + |----> forms -- programs related to form library + |----> menus -- programs related to menus library + |----> panels -- programs related to panels library + |----> perl -- perl equivalents of the examples (contributed + | by Anuradha Ratnaweera) + |----> Makefile -- the top level Makefile + |----> README -- the top level README file. contains instructions + |----> COPYING -- copyright notice</font> +</pre></td> +</tr> +</table> +<p>The individual directories contain the following files.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000">Description of files in each directory +-------------------------------------- +JustForFun + | + |----> hanoi.c -- The Towers of Hanoi Solver + |----> life.c -- The Game of Life demo + |----> magic.c -- An Odd Order Magic Square builder + |----> queens.c -- The famous N-Queens Solver + |----> shuffle.c -- A fun game, if you have time to kill + |----> tt.c -- A very trivial typing tutor + + basics + | + |----> acs_vars.c -- ACS_ variables example + |----> hello_world.c -- Simple "Hello World" Program + |----> init_func_example.c -- Initialization functions example + |----> key_code.c -- Shows the scan code of the key pressed + |----> mouse_menu.c -- A menu accessible by mouse + |----> other_border.c -- Shows usage of other border functions apa + | -- rt from box() + |----> printw_example.c -- A very simple printw() example + |----> scanw_example.c -- A very simple getstr() example + |----> simple_attr.c -- A program that can print a c file with + | -- comments in attribute + |----> simple_color.c -- A simple example demonstrating colors + |----> simple_key.c -- A menu accessible with keyboard UP, DOWN + | -- arrows + |----> temp_leave.c -- Demonstrates temporarily leaving curses mode + |----> win_border.c -- Shows Creation of windows and borders + |----> with_chgat.c -- chgat() usage example + + forms + | + |----> form_attrib.c -- Usage of field attributes + |----> form_options.c -- Usage of field options + |----> form_simple.c -- A simple form example + |----> form_win.c -- Demo of windows associated with forms + + menus + | + |----> menu_attrib.c -- Usage of menu attributes + |----> menu_item_data.c -- Usage of item_name() etc.. functions + |----> menu_multi_column.c -- Creates multi columnar menus + |----> menu_scroll.c -- Demonstrates scrolling capability of menus + |----> menu_simple.c -- A simple menu accessed by arrow keys + |----> menu_toggle.c -- Creates multi valued menus and explains + | -- REQ_TOGGLE_ITEM + |----> menu_userptr.c -- Usage of user pointer + |----> menu_win.c -- Demo of windows associated with menus + + panels + | + |----> panel_browse.c -- Panel browsing through tab. Usage of user + | -- pointer + |----> panel_hide.c -- Hiding and Un hiding of panels + |----> panel_resize.c -- Moving and resizing of panels + |----> panel_simple.c -- A simple panel example + + perl + |----> 01-10.pl -- Perl equivalents of first ten example programs</font> +</pre></td> +</tr> +</table> +<p>There is a top level Makefile included in the main directory. It +builds all the files and puts the ready-to-use exes in demo/exe +directory. You can also do selective make by going into the +corresponding directory. Each directory contains a README file +explaining the purpose of each c file in the directory.</p> +<p>For every example, I have included path name for the file +relative to the examples directory.</p> +<p>If you prefer browsing individual programs, point your browser +to <a href= +"http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/" +target= +"_top">http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p> +<p>All the programs are released under the same license that is +used by ncurses (MIT-style). This gives you the ability to do +pretty much anything other than claiming them as yours. Feel free +to use them in your programs as appropriate.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="OTHERFORMATS" id="OTHERFORMATS">1.6. +Other Formats of the document</a></h3> +<p>This howto is also availabe in various other formats on the +tldp.org site. Here are the links to other formats of this +document.</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="LISTFORMATS" id="LISTFORMATS">1.6.1. +Readily available formats from tldp.org</a></h4> +<ul> +<li> +<p><a href= +"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf" +target="_top">Acrobat PDF Format</a></p> +</li> +<li> +<p><a href= +"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz" +target="_top">PostScript Format</a></p> +</li> +<li> +<p><a href= +"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz" +target="_top">In Multiple HTML pages</a></p> +</li> +<li> +<p><a href= +"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html" +target="_top">In One big HTML format</a></p> +</li> +</ul> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="BUILDSOURCE" id="BUILDSOURCE">1.6.2. +Building from source</a></h4> +<p>If above links are broken or if you want to experiment with sgml +read on.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> Get both the source and the tar,gzipped programs, available at + http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/ + NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml + http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/ + NCURSES-HOWTO/ncurses_programs.tar.gz + + Unzip ncurses_programs.tar.gz with + tar zxvf ncurses_programs.tar.gz + + Use jade to create various formats. For example if you just want to create + the multiple html files, you would use + jade -t sgml -i html -d <path to docbook html stylesheet> + NCURSES-Programming-HOWTO.sgml + to get pdf, first create a single html file of the HOWTO with + jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks + NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html + then use htmldoc to get pdf file with + htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf> + NCURSES-ONE-BIG-FILE.html + for ps, you would use + htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps> + NCURSES-ONE-BIG-FILE.html</font> +</pre></td> +</tr> +</table> +<p>See <a href="http://www.tldp.org/LDP/LDP-Author-Guide/" target= +"_top">LDP Author guide</a> for more details. If all else failes, +mail me at <a href="ppadala@gmail.com" target= +"_top">ppadala@gmail.com</a></p> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7. +Credits</a></h3> +<p>I thank <a href="mailto:sharath_1@usa.net" target= +"_top">Sharath</a> and Emre Akbas for helping me with few sections. +The introduction was initially written by sharath. I rewrote it +with few excerpts taken from his initial work. Emre helped in +writing printw and scanw sections.</p> +<p>Perl equivalents of the example programs are contributed by +<a href="mailto:Aratnaweera@virtusa.com" target="_top">Anuradha +Ratnaweera</a>.</p> +<p>Then comes <a href="mailto:parimi@ece.arizona.edu" target= +"_top">Ravi Parimi</a>, my dearest friend, who has been on this +project before even one line was written. He constantly bombarded +me with suggestions and patiently reviewed the whole text. He also +checked each program on Linux and Solaris.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8. Wish +List</a></h3> +<p>This is the wish list, in the order of priority. If you have a +wish or you want to work on completing the wish, mail <a href= +"mailto:ppadala@gmail.com" target="_top">me</a>.</p> +<ul> +<li> +<p>Add examples to last parts of forms section.</p> +</li> +<li> +<p>Prepare a Demo showing all the programs and allow the user to +browse through description of each program. Let the user compile +and see the program in action. A dialog based interface is +preferred.</p> +</li> +<li> +<p>Add debug info. _tracef, _tracemouse stuff.</p> +</li> +<li> +<p>Accessing termcap, terminfo using functions provided by ncurses +package.</p> +</li> +<li> +<p>Working on two terminals simultaneously.</p> +</li> +<li> +<p>Add more stuff to miscellaneous section.</p> +</li> +</ul> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9. +Copyright</a></h3> +<p>Copyright © 2001 by Pradeep Padala.</p> +<p>Permission is hereby granted, free of charge, to any person +obtaining a copy of this software and associated documentation +files (the "Software"), to deal in the Software without +restriction, including without limitation the rights to use, copy, +modify, merge, publish, distribute, distribute with modifications, +sublicense, and/or sell copies of the Software, and to permit +persons to whom the Software is furnished to do so, subject to the +following conditions:</p> +<p>The above copyright notice and this permission notice shall be +included in all copies or substantial portions of the Software.</p> +<p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE +LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN +ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE.</p> +<p>Except as contained in this notice, the name(s) of the above +copyright holders shall not be used in advertising or otherwise to +promote the sale, use or other dealings in this Software without +prior written authorization.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2. Hello +World !!!</a></h2> +<p>Welcome to the world of curses. Before we plunge into the +library and look into its various features, let's write a simple +program and say hello to the world.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="COMPILECURSES" id="COMPILECURSES">2.1. +Compiling With the NCURSES Library</a></h3> +<p>To use ncurses library functions, you have to include ncurses.h +in your programs. To link the program with ncurses the flag +-lncurses should be added.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> #include <ncurses.h> + . + . + . + + compile and link: gcc <program file> -lncurses</font> +</pre></td> +</tr> +</table> +<div class="EXAMPLE"><a name="BHW" id="BHW"></a> +<p><b>Example 1. The Hello World !!! Program</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +int main() +{ + initscr(); /* Start curses mode */ + printw("Hello World !!!"); /* Print Hello World */ + refresh(); /* Print it on to the real screen */ + getch(); /* Wait for user input */ + endwin(); /* End curses mode */ + + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2. +Dissection</a></h3> +<p>The above program prints "Hello World !!!" to the screen and +exits. This program shows how to initialize curses and do screen +manipulation and end curses mode. Let's dissect it line by +line.</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="ABOUT-INITSCR" id="ABOUT-INITSCR">2.2.1. +About initscr()</a></h4> +<p>The function initscr() initializes the terminal in curses mode. +In some implementations, it clears the screen and presents a blank +screen. To do any screen manipulation using curses package this has +to be called first. This function initializes the curses system and +allocates memory for our present window (called <var class= +"LITERAL">stdscr</var>) and some other data-structures. Under +extreme cases this function might fail due to insufficient memory +to allocate memory for curses library's data structures.</p> +<p>After this is done, we can do a variety of initializations to +customize our curses settings. These details will be explained +<a href="#INIT">later</a> .</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="MYST-REFRESH" id="MYST-REFRESH">2.2.2. +The mysterious refresh()</a></h4> +<p>The next line printw prints the string "Hello World !!!" on to +the screen. This function is analogous to normal printf in all +respects except that it prints the data on a window called stdscr +at the current (y,x) co-ordinates. Since our present co-ordinates +are at 0,0 the string is printed at the left hand corner of the +window.</p> +<p>This brings us to that mysterious refresh(). Well, when we +called printw the data is actually written to an imaginary window, +which is not updated on the screen yet. The job of printw is to +update a few flags and data structures and write the data to a +buffer corresponding to stdscr. In order to show it on the screen, +we need to call refresh() and tell the curses system to dump the +contents on the screen.</p> +<p>The philosophy behind all this is to allow the programmer to do +multiple updates on the imaginary screen or windows and do a +refresh once all his screen update is done. refresh() checks the +window and updates only the portion which has been changed. This +improves performance and offers greater flexibility too. But, it is +sometimes frustrating to beginners. A common mistake committed by +beginners is to forget to call refresh() after they did some update +through printw() class of functions. I still forget to add it +sometimes :-)</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="ABOUT-ENDWIN" id="ABOUT-ENDWIN">2.2.3. +About endwin()</a></h4> +<p>And finally don't forget to end the curses mode. Otherwise your +terminal might behave strangely after the program quits. endwin() +frees the memory taken by curses sub-system and its data structures +and puts the terminal in normal mode. This function must be called +after you are done with the curses mode.</p> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory +Details</a></h2> +<p>Now that we have seen how to write a simple curses program let's +get into the details. There are many functions that help customize +what you see on screen and many features which can be put to full +use.</p> +<p>Here we go...</p> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="INIT" id="INIT">4. +Initialization</a></h2> +<p>We now know that to initialize curses system the function +initscr() has to be called. There are functions which can be called +after this initialization to customize our curses session. We may +ask the curses system to set the terminal in raw mode or initialize +color or initialize the mouse etc.. Let's discuss some of the +functions that are normally called immediately after initscr();</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1. +Initialization functions</a></h3> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2. raw() and +cbreak()</a></h3> +<p>Normally the terminal driver buffers the characters a user types +until a new line or carriage return is encountered. But most +programs require that the characters be available as soon as the +user types them. The above two functions are used to disable line +buffering. The difference between these two functions is in the way +control characters like suspend (CTRL-Z), interrupt and quit +(CTRL-C) are passed to the program. In the raw() mode these +characters are directly passed to the program without generating a +signal. In the <var class="LITERAL">cbreak()</var> mode these +control characters are interpreted as any other character by the +terminal driver. I personally prefer to use raw() as I can exercise +greater control over what the user does.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3. echo() +and noecho()</a></h3> +<p>These functions control the echoing of characters typed by the +user to the terminal. <var class="LITERAL">noecho()</var> switches +off echoing. The reason you might want to do this is to gain more +control over echoing or to suppress unnecessary echoing while +taking input from the user through the getch() etc. functions. Most +of the interactive programs call <var class= +"LITERAL">noecho()</var> at initialization and do the echoing of +characters in a controlled manner. It gives the programmer the +flexibility of echoing characters at any place in the window +without updating current (y,x) co-ordinates.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4. +keypad()</a></h3> +<p>This is my favorite initialization function. It enables the +reading of function keys like F1, F2, arrow keys etc. Almost every +interactive program enables this, as arrow keys are a major part of +any User Interface. Do <var class="LITERAL">keypad(stdscr, +TRUE)</var> to enable this feature for the regular screen (stdscr). +You will learn more about key management in later sections of this +document.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5. +halfdelay()</a></h3> +<p>This function, though not used very often, is a useful one at +times. halfdelay()is called to enable the half-delay mode, which is +similar to the cbreak() mode in that characters typed are +immediately available to program. However, it waits for 'X' tenths +of a second for input and then returns ERR, if no input is +available. 'X' is the timeout value passed to the function +halfdelay(). This function is useful when you want to ask the user +for input, and if he doesn't respond with in certain time, we can +do some thing else. One possible example is a timeout at the +password prompt.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6. +Miscellaneous Initialization functions</a></h3> +<p>There are few more functions which are called at initialization +to customize curses behavior. They are not used as extensively as +those mentioned above. Some of them are explained where +appropriate.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An +Example</a></h3> +<p>Let's write a program which will clarify the usage of these +functions.</p> +<div class="EXAMPLE"><a name="BINFU" id="BINFU"></a> +<p><b>Example 2. Initialization Function Usage example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +int main() +{ int ch; + + initscr(); /* Start curses mode */ + raw(); /* Line buffering disabled */ + keypad(stdscr, TRUE); /* We get F1, F2 etc.. */ + noecho(); /* Don't echo() while we do getch */ + + printw("Type any character to see it in bold\n"); + ch = getch(); /* If raw() hadn't been called + * we have to press enter before it + * gets to the program */ + if(ch == KEY_F(1)) /* Without keypad enabled this will */ + printw("F1 Key pressed");/* not get to us either */ + /* Without noecho() some ugly escape + * charachters might have been printed + * on screen */ + else + { printw("The pressed key is "); + attron(A_BOLD); + printw("%c", ch); + attroff(A_BOLD); + } + refresh(); /* Print it on to the real screen */ + getch(); /* Wait for user input */ + endwin(); /* End curses mode */ + + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>This program is self-explanatory. But I used functions which +aren't explained yet. The function <var class= +"LITERAL">getch()</var> is used to get a character from user. It is +equivalent to normal <var class="LITERAL">getchar()</var> except +that we can disable the line buffering to avoid <enter> after +input. Look for more about <var class="LITERAL">getch()</var>and +reading keys in the <a href="#KEYS">key management section</a> . +The functions attron and attroff are used to switch some attributes +on and off respectively. In the example I used them to print the +character in bold. These functions are explained in detail +later.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5. A +Word about Windows</a></h2> +<p>Before we plunge into the myriad ncurses functions, let me clear +few things about windows. Windows are explained in detail in +following <a href="#WINDOWS">sections</a></p> +<p>A Window is an imaginary screen defined by curses system. A +window does not mean a bordered window which you usually see on +Win9X platforms. When curses is initialized, it creates a default +window named <var class="LITERAL">stdscr</var> which represents +your 80x25 (or the size of window in which you are running) screen. +If you are doing simple tasks like printing few strings, reading +input etc., you can safely use this single window for all of your +purposes. You can also create windows and call functions which +explicitly work on the specified window.</p> +<p>For example, if you call</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> printw("Hi There !!!"); + refresh();</font> +</pre></td> +</tr> +</table> +<p>It prints the string on stdscr at the present cursor position. +Similarly the call to refresh(), works on stdscr only.</p> +<p>Say you have created <a href="#WINDOWS">windows</a> then you +have to call a function with a 'w' added to the usual function.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> wprintw(win, "Hi There !!!"); + wrefresh(win);</font> +</pre></td> +</tr> +</table> +<p>As you will see in the rest of the document, naming of functions +follow the same convention. For each function there usually are +three more functions.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> printw(string); /* Print on stdscr at present cursor position */ + mvprintw(y, x, string);/* Move to (y, x) then print string */ + wprintw(win, string); /* Print on window win at present cursor position */ + /* in the window */ + mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */ + /* co-ordinates and then print */</font> +</pre></td> +</tr> +</table> +<p>Usually the w-less functions are macros which expand to +corresponding w-function with stdscr as the window parameter.</p> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output +functions</a></h2> +<p>I guess you can't wait any more to see some action. Back to our +odyssey of curses functions. Now that curses is initialized, let's +interact with world.</p> +<p>There are three classes of functions which you can use to do +output on screen.</p> +<ol type="1"> +<li> +<p>addch() class: Print single character with attributes</p> +</li> +<li> +<p>printw() class: Print formatted output similar to printf()</p> +</li> +<li> +<p>addstr() class: Print strings</p> +</li> +</ol> +<p>These functions can be used interchangeably and it's a matter of +style as to which class is used. Let's see each one in detail.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1. addch() +class of functions</a></h3> +<p>These functions put a single character into the current cursor +location and advance the position of the cursor. You can give the +character to be printed but they usually are used to print a +character with some attributes. Attributes are explained in detail +in later <a href="#ATTRIB">sections</a> of the document. If a +character is associated with an attribute(bold, reverse video +etc.), when curses prints the character, it is printed in that +attribute.</p> +<p>In order to combine a character with some attributes, you have +two options:</p> +<ul> +<li> +<p>By OR'ing a single character with the desired attribute macros. +These attribute macros could be found in the header file +<var class="LITERAL">ncurses.h</var>. For example, you want to +print a character ch(of type char) bold and underlined, you would +call addch() as below.</p> +<table border="0" bgcolor="#E0E0E0" width="90%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> addch(ch | A_BOLD | A_UNDERLINE);</font> +</pre></td> +</tr> +</table> +</li> +<li> +<p>By using functions like <var class= +"LITERAL">attrset(),attron(),attroff()</var>. These functions are +explained in the <a href="#ATTRIB">Attributes</a> section. Briefly, +they manipulate the current attributes of the given window. Once +set, the character printed in the window are associated with the +attributes until it is turned off.</p> +</li> +</ul> +<p>Additionally, <var class="LITERAL">curses</var> provides some +special characters for character-based graphics. You can draw +tables, horizontal or vertical lines, etc. You can find all +avaliable characters in the header file <var class= +"LITERAL">ncurses.h</var>. Try looking for macros beginning with +<var class="LITERAL">ACS_</var> in this file.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="AEN298" id="AEN298">6.2. mvaddch(), +waddch() and mvwaddch()</a></h3> +<p><var class="LITERAL">mvaddch()</var> is used to move the cursor +to a given point, and then print. Thus, the calls:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> move(row,col); /* moves the cursor to row<em>th</em> row and col<em>th</em> column */ + addch(ch);</font> +</pre></td> +</tr> +</table> +can be replaced by +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> mvaddch(row,col,ch);</font> +</pre></td> +</tr> +</table> +<p><var class="LITERAL">waddch()</var> is similar to <var class= +"LITERAL">addch()</var>, except that it adds a character into the +given window. (Note that <var class="LITERAL">addch()</var> adds a +character into the window <var class="LITERAL">stdscr</var>.)</p> +<p>In a similar fashion <var class="LITERAL">mvwaddch()</var> +function is used to add a character into the given window at the +given coordinates.</p> +<p>Now, we are familiar with the basic output function <var class= +"LITERAL">addch()</var>. But, if we want to print a string, it +would be very annoying to print it character by character. +Fortunately, <var class="LITERAL">ncurses</var> provides +<var class="LITERAL">printf</var><em>-like</em> or <var class= +"LITERAL">puts</var><em>-like</em> functions.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PRINTWCLASS" id="PRINTWCLASS">6.3. +printw() class of functions</a></h3> +<p>These functions are similar to <var class= +"LITERAL">printf()</var> with the added capability of printing at +any position on the screen.</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="PRINTWMVPRINTW" id= +"PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4> +<p>These two functions work much like <var class= +"LITERAL">printf()</var>. <var class="LITERAL">mvprintw()</var> can +be used to move the cursor to a position and then print. If you +want to move the cursor first and then print using <var class= +"LITERAL">printw()</var> function, use <var class= +"LITERAL">move()</var> first and then use <var class= +"LITERAL">printw()</var> though I see no point why one should avoid +using <var class="LITERAL">mvprintw()</var>, you have the +flexibility to manipulate.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id= +"WPRINTWMVWPRINTW">6.3.2. wprintw() and mvwprintw</a></h4> +<p>These two functions are similar to above two except that they +print in the corresponding window given as argument.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3. +vwprintw()</a></h4> +<p>This function is similar to <var class= +"LITERAL">vprintf()</var>. This can be used when variable number of +arguments are to be printed.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="SIMPLEPRINTWEX" id= +"SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4> +<div class="EXAMPLE"><a name="BPREX" id="BPREX"></a> +<p><b>Example 3. A Simple printw example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */ +#include <string.h> + +int main() +{ + char mesg[]="Just a string"; /* message to be appeared on the screen */ + int row,col; /* to store the number of rows and * + * the number of colums of the screen */ + initscr(); /* start the curses mode */ + getmaxyx(stdscr,row,col); /* get the number of rows and columns */ + mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg); + /* print the message at the center of the screen */ + mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col); + printw("Try resizing your window(if possible) and then run this program again"); + refresh(); + getch(); + endwin(); + + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>Above program demonstrates how easy it is to use <var class= +"LITERAL">printw</var>. You just feed the coordinates and the +message to be appeared on the screen, then it does what you +want.</p> +<p>The above program introduces us to a new function <var class= +"LITERAL">getmaxyx()</var>, a macro defined in <var class= +"LITERAL">ncurses.h</var>. It gives the number of columns and the +number of rows in a given window. <var class= +"LITERAL">getmaxyx()</var> does this by updating the variables +given to it. Since <var class="LITERAL">getmaxyx()</var> is not a +function we don't pass pointers to it, we just give two integer +variables.</p> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ADDSTRCLASS" id="ADDSTRCLASS">6.4. +addstr() class of functions</a></h3> +<p><var class="LITERAL">addstr()</var> is used to put a character +string into a given window. This function is similar to calling +<var class="LITERAL">addch()</var> once for each character in a +given string. This is true for all output functions. There are +other functions from this family such as <var class= +"LITERAL">mvaddstr(),mvwaddstr()</var> and <var class= +"LITERAL">waddstr()</var>, which obey the naming convention of +curses.(e.g. mvaddstr() is similar to the respective calls move() +and then addstr().) Another function of this family is addnstr(), +which takes an integer parameter(say n) additionally. This function +puts at most n characters into the screen. If n is negative, then +the entire string will be added.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A word of +caution</a></h3> +<p>All these functions take y co-ordinate first and then x in their +arguments. A common mistake by beginners is to pass x,y in that +order. If you are doing too many manipulations of (y,x) +co-ordinates, think of dividing the screen into windows and +manipulate each one separately. Windows are explained in the +<a href="#WINDOWS">windows</a> section.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input +functions</a></h2> +<p>Well, printing without taking input, is boring. Let's see +functions which allow us to get input from user. These functions +also can be divided into three categories.</p> +<ol type="1"> +<li> +<p>getch() class: Get a character</p> +</li> +<li> +<p>scanw() class: Get formatted input</p> +</li> +<li> +<p>getstr() class: Get strings</p> +</li> +</ol> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1. getch() +class of functions</a></h3> +<p>These functions read a single character from the terminal. But +there are several subtle facts to consider. For example if you +don't use the function cbreak(), curses will not read your input +characters contiguously but will begin read them only after a new +line or an EOF is encountered. In order to avoid this, the cbreak() +function must used so that characters are immediately available to +your program. Another widely used function is noecho(). As the name +suggests, when this function is set (used), the characters that are +keyed in by the user will not show up on the screen. The two +functions cbreak() and noecho() are typical examples of key +management. Functions of this genre are explained in the <a href= +"#KEYS">key management section</a> .</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2. scanw() +class of functions</a></h3> +<p>These functions are similar to <var class= +"LITERAL">scanf()</var> with the added capability of getting the +input from any location on the screen.</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="SCANWMVSCANW" id="SCANWMVSCANW">7.2.1. +scanw() and mvscanw</a></h4> +<p>The usage of these functions is similar to that of <var class= +"LITERAL">sscanf()</var>, where the line to be scanned is provided +by <var class="LITERAL">wgetstr()</var> function. That is, these +functions call to <var class="LITERAL">wgetstr()</var> +function(explained below) and uses the resulting line for a +scan.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="WSCANWMVWSCANW" id= +"WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4> +<p>These are similar to above two functions except that they read +from a window, which is supplied as one of the arguments to these +functions.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3. +vwscanw()</a></h4> +<p>This function is similar to <var class="LITERAL">vscanf()</var>. +This can be used when a variable number of arguments are to be +scanned.</p> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="GETSTRCLASS" id="GETSTRCLASS">7.3. +getstr() class of functions</a></h3> +<p>These functions are used to get strings from the terminal. In +essence, this function performs the same task as would be achieved +by a series of calls to <var class="LITERAL">getch()</var> until a +newline, carriage return, or end-of-file is received. The resulting +string of characters are pointed to by <var class= +"LITERAL">str</var>, which is a character pointer provided by the +user.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4. Some +examples</a></h3> +<div class="EXAMPLE"><a name="BSCEX" id="BSCEX"></a> +<p><b>Example 4. A Simple scanw example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> /* ncurses.h includes stdio.h */ +#include <string.h> + +int main() +{ + char mesg[]="Enter a string: "; /* message to be appeared on the screen */ + char str[80]; + int row,col; /* to store the number of rows and * + * the number of colums of the screen */ + initscr(); /* start the curses mode */ + getmaxyx(stdscr,row,col); /* get the number of rows and columns */ + mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg); + /* print the message at the center of the screen */ + getstr(str); + mvprintw(LINES - 2, 0, "You Entered: %s", str); + getch(); + endwin(); + + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8. +Attributes</a></h2> +<p>We have seen an example of how attributes can be used to print +characters with some special effects. Attributes, when set +prudently, can present information in an easy, understandable +manner. The following program takes a C file as input and prints +the file with comments in bold. Scan through the code.</p> +<div class="EXAMPLE"><a name="BSIAT" id="BSIAT"></a> +<p><b>Example 5. A Simple Attributes example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */ +#include <ncurses.h> +#include <stdlib.h> + +int main(int argc, char *argv[]) +{ + int ch, prev, row, col; + prev = EOF; + FILE *fp; + int y, x; + + if(argc != 2) + { + printf("Usage: %s <a c file name>\n", argv[0]); + exit(1); + } + fp = fopen(argv[1], "r"); + if(fp == NULL) + { + perror("Cannot open input file"); + exit(1); + } + initscr(); /* Start curses mode */ + getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */ + while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */ + { + getyx(stdscr, y, x); /* get the current curser position */ + if(y == (row - 1)) /* are we are at the end of the screen */ + { + printw("<-Press Any Key->"); /* tell the user to press a key */ + getch(); + clear(); /* clear the screen */ + move(0, 0); /* start at the beginning of the screen */ + } + if(prev == '/' && ch == '*') /* If it is / and * then only + * switch bold on */ + { + attron(A_BOLD); /* cut bold on */ + getyx(stdscr, y, x); /* get the current curser position */ + move(y, x - 1); /* back up one space */ + printw("%c%c", '/', ch); /* The actual printing is done here */ + } + else + printw("%c", ch); + refresh(); + if(prev == '*' && ch == '/') + attroff(A_BOLD); /* Switch it off once we got * + * and then / */ + prev = ch; + } + endwin(); /* End curses mode */ + fclose(fp); + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>Don't worry about all those initialization and other crap. +Concentrate on the while loop. It reads each character in the file +and searches for the pattern /*. Once it spots the pattern, it +switches the BOLD attribute on with <var class= +"LITERAL">attron()</var> . When we get the pattern */ it is +switched off by <var class="LITERAL">attroff()</var> .</p> +<p>The above program also introduces us to two useful functions +<var class="LITERAL">getyx()</var> and <var class= +"LITERAL">move()</var>. The first function gets the co-ordinates of +the present cursor into the variables y, x. Since getyx() is a +macro we don't have to pass pointers to variables. The function +<var class="LITERAL">move()</var> moves the cursor to the +co-ordinates given to it.</p> +<p>The above program is really a simple one which doesn't do much. +On these lines one could write a more useful program which reads a +C file, parses it and prints it in different colors. One could even +extend it to other languages as well.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ATTRIBDETAILS" id="ATTRIBDETAILS">8.1. +The details</a></h3> +<p>Let's get into more details of attributes. The functions +<var class="LITERAL">attron(), attroff(), attrset()</var> , and +their sister functions <var class="LITERAL">attr_get()</var> etc.. +can be used to switch attributes on/off , get attributes and +produce a colorful display.</p> +<p>The functions attron and attroff take a bit-mask of attributes +and switch them on or off, respectively. The following video +attributes, which are defined in <curses.h> can be passed to +these functions.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> + A_NORMAL Normal display (no highlight) + A_STANDOUT Best highlighting mode of the terminal. + A_UNDERLINE Underlining + A_REVERSE Reverse video + A_BLINK Blinking + A_DIM Half bright + A_BOLD Extra bright or bold + A_PROTECT Protected mode + A_INVIS Invisible or blank mode + A_ALTCHARSET Alternate character set + A_CHARTEXT Bit-mask to extract a character + COLOR_PAIR(n) Color-pair number n + </font> +</pre></td> +</tr> +</table> +<p>The last one is the most colorful one :-) Colors are explained +in the <a href="#color" target="_top">next sections</a>.</p> +<p>We can OR(|) any number of above attributes to get a combined +effect. If you wanted reverse video with blinking characters you +can use</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> attron(A_REVERSE | A_BLINK);</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ATTRONVSATTRSET" id= +"ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3> +<p>Then what is the difference between attron() and attrset()? +attrset sets the attributes of window whereas attron just switches +on the attribute given to it. So attrset() fully overrides whatever +attributes the window previously had and sets it to the new +attribute(s). Similarly attroff() just switches off the +attribute(s) given to it as an argument. This gives us the +flexibility of managing attributes easily.But if you use them +carelessly you may loose track of what attributes the window has +and garble the display. This is especially true while managing +menus with colors and highlighting. So decide on a consistent +policy and stick to it. You can always use <var class= +"LITERAL">standend()</var> which is equivalent to <var class= +"LITERAL">attrset(A_NORMAL)</var> which turns off all attributes +and brings you to normal mode.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ATTR_GET" id="ATTR_GET">8.3. +attr_get()</a></h3> +<p>The function attr_get() gets the current attributes and color +pair of the window. Though we might not use this as often as the +above functions, this is useful in scanning areas of screen. Say we +wanted to do some complex update on screen and we are not sure what +attribute each character is associated with. Then this function can +be used with either attrset or attron to produce the desired +effect.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ATTR_FUNCS" id="ATTR_FUNCS">8.4. attr_ +functions</a></h3> +<p>There are series of functions like attr_set(), attr_on etc.. +These are similar to above functions except that they take +parameters of type <var class="LITERAL">attr_t</var>.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5. wattr +functions</a></h3> +<p>For each of the above functions we have a corresponding function +with 'w' which operates on a particular window. The above functions +operate on stdscr.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat() +functions</a></h3> +<p>The function chgat() is listed in the end of the man page +curs_attr. It actually is a useful one. This function can be used +to set attributes for a group of characters without moving. I mean +it !!! without moving the cursor :-) It changes the attributes of a +given number of characters starting at the current cursor +location.</p> +<p>We can give -1 as the character count to update till end of +line. If you want to change attributes of characters from current +position to end of line, just use this.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> chgat(-1, A_REVERSE, 0, NULL);</font> +</pre></td> +</tr> +</table> +<p>This function is useful when changing attributes for characters +that are already on the screen. Move to the character from which +you want to change and change the attribute.</p> +<p>Other functions wchgat(), mvchgat(), wchgat() behave similarly +except that the w functions operate on the particular window. The +mv functions first move the cursor then perform the work given to +them. Actually chgat is a macro which is replaced by a wchgat() +with stdscr as the window. Most of the "w-less" functions are +macros.</p> +<div class="EXAMPLE"><a name="BWICH" id="BWICH"></a> +<p><b>Example 6. Chgat() Usage example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +int main(int argc, char *argv[]) +{ initscr(); /* Start curses mode */ + start_color(); /* Start color functionality */ + + init_pair(1, COLOR_CYAN, COLOR_BLACK); + printw("A Big string which i didn't care to type fully "); + mvchgat(0, 0, -1, A_BLINK, 1, NULL); + /* + * First two parameters specify the position at which to start + * Third parameter number of characters to update. -1 means till + * end of line + * Forth parameter is the normal attribute you wanted to give + * to the charcter + * Fifth is the color index. It is the index given during init_pair() + * use 0 if you didn't want color + * Sixth one is always NULL + */ + refresh(); + getch(); + endwin(); /* End curses mode */ + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>This example also introduces us to the color world of curses. +Colors will be explained in detail later. Use 0 for no color.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9. +Windows</a></h2> +<p>Windows form the most important concept in curses. You have seen +the standard window stdscr above where all the functions implicitly +operated on this window. Now to make design even a simplest GUI, +you need to resort to windows. The main reason you may want to use +windows is to manipulate parts of the screen separately, for better +efficiency, by updating only the windows that need to be changed +and for a better design. I would say the last reason is the most +important in going for windows. You should always strive for a +better and easy-to-manage design in your programs. If you are +writing big, complex GUIs this is of pivotal importance before you +start doing anything.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WINDOWBASICS" id="WINDOWBASICS">9.1. The +basics</a></h3> +<p>A Window can be created by calling the function <var class= +"LITERAL">newwin()</var>. It doesn't create any thing on the screen +actually. It allocates memory for a structure to manipulate the +window and updates the structure with data regarding the window +like it's size, beginy, beginx etc.. Hence in curses, a window is +just an abstraction of an imaginary window, which can be +manipulated independent of other parts of screen. The function +newwin() returns a pointer to structure WINDOW, which can be passed +to window related functions like wprintw() etc.. Finally the window +can be destroyed with delwin(). It will deallocate the memory +associated with the window structure.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="LETBEWINDOW" id="LETBEWINDOW">9.2. Let +there be a Window !!!</a></h3> +<p>What fun is it, if a window is created and we can't see it. So +the fun part begins by displaying the window. The function +<var class="LITERAL">box()</var> can be used to draw a border +around the window. Let's explore these functions in more detail in +this example.</p> +<div class="EXAMPLE"><a name="BWIBO" id="BWIBO"></a> +<p><b>Example 7. Window Border example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + + +WINDOW *create_newwin(int height, int width, int starty, int startx); +void destroy_win(WINDOW *local_win); + +int main(int argc, char *argv[]) +{ WINDOW *my_win; + int startx, starty, width, height; + int ch; + + initscr(); /* Start curses mode */ + cbreak(); /* Line buffering disabled, Pass on + * everty thing to me */ + keypad(stdscr, TRUE); /* I need that nifty F1 */ + + height = 3; + width = 10; + starty = (LINES - height) / 2; /* Calculating for a center placement */ + startx = (COLS - width) / 2; /* of the window */ + printw("Press F1 to exit"); + refresh(); + my_win = create_newwin(height, width, starty, startx); + + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case KEY_LEFT: + destroy_win(my_win); + my_win = create_newwin(height, width, starty,--startx); + break; + case KEY_RIGHT: + destroy_win(my_win); + my_win = create_newwin(height, width, starty,++startx); + break; + case KEY_UP: + destroy_win(my_win); + my_win = create_newwin(height, width, --starty,startx); + break; + case KEY_DOWN: + destroy_win(my_win); + my_win = create_newwin(height, width, ++starty,startx); + break; + } + } + + endwin(); /* End curses mode */ + return 0; +} + +WINDOW *create_newwin(int height, int width, int starty, int startx) +{ WINDOW *local_win; + + local_win = newwin(height, width, starty, startx); + box(local_win, 0 , 0); /* 0, 0 gives default characters + * for the vertical and horizontal + * lines */ + wrefresh(local_win); /* Show that box */ + + return local_win; +} + +void destroy_win(WINDOW *local_win) +{ + /* box(local_win, ' ', ' '); : This won't produce the desired + * result of erasing the window. It will leave it's four corners + * and so an ugly remnant of window. + */ + wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' '); + /* The parameters taken are + * 1. win: the window on which to operate + * 2. ls: character to be used for the left side of the window + * 3. rs: character to be used for the right side of the window + * 4. ts: character to be used for the top side of the window + * 5. bs: character to be used for the bottom side of the window + * 6. tl: character to be used for the top left corner of the window + * 7. tr: character to be used for the top right corner of the window + * 8. bl: character to be used for the bottom left corner of the window + * 9. br: character to be used for the bottom right corner of the window + */ + wrefresh(local_win); + delwin(local_win); +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="BORDEREXEXPL" id="BORDEREXEXPL">9.3. +Explanation</a></h3> +<p>Don't scream. I know it's a big example. But I have to explain +some important things here :-). This program creates a rectangular +window that can be moved with left, right, up, down arrow keys. It +repeatedly creates and destroys windows as user press a key. Don't +go beyond the screen limits. Checking for those limits is left as +an exercise for the reader. Let's dissect it by line by line.</p> +<p>The <var class="LITERAL">create_newwin()</var> function creates +a window with <var class="LITERAL">newwin()</var> and displays a +border around it with box. The function <var class= +"LITERAL">destroy_win()</var> first erases the window from screen +by painting a border with ' ' character and then calling +<var class="LITERAL">delwin()</var> to deallocate memory related to +it. Depending on the key the user presses, starty or startx is +changed and a new window is created.</p> +<p>In the destroy_win, as you can see, I used wborder instead of +box. The reason is written in the comments (You missed it. I know. +Read the code :-)). wborder draws a border around the window with +the characters given to it as the 4 corner points and the 4 lines. +To put it clearly, if you have called wborder as below:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> wborder(win, '|', '|', '-', '-', '+', '+', '+', '+');</font> +</pre></td> +</tr> +</table> +<p>it produces some thing like</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> +------------+ + | | + | | + | | + | | + | | + | | + +------------+</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4. The +other stuff in the example</a></h3> +<p>You can also see in the above examples, that I have used the +variables COLS, LINES which are initialized to the screen sizes +after initscr(). They can be useful in finding screen dimensions +and finding the center co-ordinate of the screen as above. The +function <var class="LITERAL">getch()</var> as usual gets the key +from keyboard and according to the key it does the corresponding +work. This type of switch- case is very common in any GUI based +programs.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="OTHERBORDERFUNCS" id= +"OTHERBORDERFUNCS">9.5. Other Border functions</a></h3> +<p>Above program is grossly inefficient in that with each press of +a key, a window is destroyed and another is created. So let's write +a more efficient program which uses other border related +functions.</p> +<p>The following program uses <var class="LITERAL">mvhline()</var> +and <var class="LITERAL">mvvline()</var> to achieve similar effect. +These two functions are simple. They create a horizontal or +vertical line of the specified length at the specified +position.</p> +<div class="EXAMPLE"><a name="BOTBO" id="BOTBO"></a> +<p><b>Example 8. More border functions</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +typedef struct _win_border_struct { + chtype ls, rs, ts, bs, + tl, tr, bl, br; +}WIN_BORDER; + +typedef struct _WIN_struct { + + int startx, starty; + int height, width; + WIN_BORDER border; +}WIN; + +void init_win_params(WIN *p_win); +void print_win_params(WIN *p_win); +void create_box(WIN *win, bool flag); + +int main(int argc, char *argv[]) +{ WIN win; + int ch; + + initscr(); /* Start curses mode */ + start_color(); /* Start the color functionality */ + cbreak(); /* Line buffering disabled, Pass on + * everty thing to me */ + keypad(stdscr, TRUE); /* I need that nifty F1 */ + noecho(); + init_pair(1, COLOR_CYAN, COLOR_BLACK); + + /* Initialize the window parameters */ + init_win_params(&win); + print_win_params(&win); + + attron(COLOR_PAIR(1)); + printw("Press F1 to exit"); + refresh(); + attroff(COLOR_PAIR(1)); + + create_box(&win, TRUE); + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case KEY_LEFT: + create_box(&win, FALSE); + --win.startx; + create_box(&win, TRUE); + break; + case KEY_RIGHT: + create_box(&win, FALSE); + ++win.startx; + create_box(&win, TRUE); + break; + case KEY_UP: + create_box(&win, FALSE); + --win.starty; + create_box(&win, TRUE); + break; + case KEY_DOWN: + create_box(&win, FALSE); + ++win.starty; + create_box(&win, TRUE); + break; + } + } + endwin(); /* End curses mode */ + return 0; +} +void init_win_params(WIN *p_win) +{ + p_win->height = 3; + p_win->width = 10; + p_win->starty = (LINES - p_win->height)/2; + p_win->startx = (COLS - p_win->width)/2; + + p_win->border.ls = '|'; + p_win->border.rs = '|'; + p_win->border.ts = '-'; + p_win->border.bs = '-'; + p_win->border.tl = '+'; + p_win->border.tr = '+'; + p_win->border.bl = '+'; + p_win->border.br = '+'; + +} +void print_win_params(WIN *p_win) +{ +#ifdef _DEBUG + mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty, + p_win->width, p_win->height); + refresh(); +#endif +} +void create_box(WIN *p_win, bool flag) +{ int i, j; + int x, y, w, h; + + x = p_win->startx; + y = p_win->starty; + w = p_win->width; + h = p_win->height; + + if(flag == TRUE) + { mvaddch(y, x, p_win->border.tl); + mvaddch(y, x + w, p_win->border.tr); + mvaddch(y + h, x, p_win->border.bl); + mvaddch(y + h, x + w, p_win->border.br); + mvhline(y, x + 1, p_win->border.ts, w - 1); + mvhline(y + h, x + 1, p_win->border.bs, w - 1); + mvvline(y + 1, x, p_win->border.ls, h - 1); + mvvline(y + 1, x + w, p_win->border.rs, h - 1); + + } + else + for(j = y; j <= y + h; ++j) + for(i = x; i <= x + w; ++i) + mvaddch(j, i, ' '); + + refresh(); + +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="COLOR" id="COLOR">10. Colors</a></h2> +<div class="SECT2"> +<h3 class="SECT2"><a name="COLORBASICS" id="COLORBASICS">10.1. The +basics</a></h3> +<p>Life seems dull with no colors. Curses has a nice mechanism to +handle colors. Let's get into the thick of the things with a small +program.</p> +<div class="EXAMPLE"><a name="BSICO" id="BSICO"></a> +<p><b>Example 9. A Simple Color example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string); +int main(int argc, char *argv[]) +{ initscr(); /* Start curses mode */ + if(has_colors() == FALSE) + { endwin(); + printf("Your terminal does not support color\n"); + exit(1); + } + start_color(); /* Start color */ + init_pair(1, COLOR_RED, COLOR_BLACK); + + attron(COLOR_PAIR(1)); + print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ..."); + attroff(COLOR_PAIR(1)); + getch(); + endwin(); +} +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + mvwprintw(win, y, x, "%s", string); + refresh(); +} +</span></font> +</pre></td> +</tr> +</table> +</div> +<p>As you can see, to start using color, you should first call the +function <var class="LITERAL">start_color()</var>. After that, you +can use color capabilities of your terminals using various +functions. To find out whether a terminal has color capabilities or +not, you can use <var class="LITERAL">has_colors()</var> function, +which returns FALSE if the terminal does not support color.</p> +<p>Curses initializes all the colors supported by terminal when +start_color() is called. These can be accessed by the define +constants like <var class="LITERAL">COLOR_BLACK</var> etc. Now to +actually start using colors, you have to define pairs. Colors are +always used in pairs. That means you have to use the function +<var class="LITERAL">init_pair()</var> to define the foreground and +background for the pair number you give. After that that pair +number can be used as a normal attribute with <var class= +"LITERAL">COLOR_PAIR()</var>function. This may seem to be +cumbersome at first. But this elegant solution allows us to manage +color pairs very easily. To appreciate it, you have to look into +the the source code of "dialog", a utility for displaying dialog +boxes from shell scripts. The developers have defined foreground +and background combinations for all the colors they might need and +initialized at the beginning. This makes it very easy to set +attributes just by accessing a pair which we already have defined +as a constant.</p> +<p>The following colors are defined in <var class= +"LITERAL">curses.h</var>. You can use these as parameters for +various color functions.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> COLOR_BLACK 0 + COLOR_RED 1 + COLOR_GREEN 2 + COLOR_YELLOW 3 + COLOR_BLUE 4 + COLOR_MAGENTA 5 + COLOR_CYAN 6 + COLOR_WHITE 7</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="CHANGECOLORDEFS" id= +"CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3> +<p>The function <var class="LITERAL">init_color()</var>can be used +to change the rgb values for the colors defined by curses +initially. Say you wanted to lighten the intensity of red color by +a minuscule. Then you can use this function as</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> init_color(COLOR_RED, 700, 0, 0); + /* param 1 : color name + * param 2, 3, 4 : rgb content min = 0, max = 1000 */</font> +</pre></td> +</tr> +</table> +<p>If your terminal cannot change the color definitions, the +function returns ERR. The function <var class= +"LITERAL">can_change_color()</var> can be used to find out whether +the terminal has the capability of changing color content or not. +The rgb content is scaled from 0 to 1000. Initially RED color is +defined with content 1000(r), 0(g), 0(b).</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="COLORCONTENT" id="COLORCONTENT">10.3. +Color Content</a></h3> +<p>The functions <var class="LITERAL">color_content()</var> and +<var class="LITERAL">pair_content()</var> can be used to find the +color content and foreground, background combination for the +pair.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing with the +key board</a></h2> +<div class="SECT2"> +<h3 class="SECT2"><a name="KEYSBASICS" id="KEYSBASICS">11.1. The +Basics</a></h3> +<p>No GUI is complete without a strong user interface and to +interact with the user, a curses program should be sensitive to key +presses or the mouse actions done by the user. Let's deal with the +keys first.</p> +<p>As you have seen in almost all of the above examples, it's very +easy to get key input from the user. A simple way of getting key +presses is to use <var class="LITERAL">getch()</var> function. The +cbreak mode should be enabled to read keys when you are interested +in reading individual key hits rather than complete lines of text +(which usually end with a carriage return). keypad should be +enabled to get the Functions keys, arrow keys etc. See the +initialization section for details.</p> +<p><var class="LITERAL">getch()</var> returns an integer +corresponding to the key pressed. If it is a normal character, the +integer value will be equivalent to the character. Otherwise it +returns a number which can be matched with the constants defined in +<var class="LITERAL">curses.h</var>. For example if the user +presses F1, the integer returned is 265. This can be checked using +the macro KEY_F() defined in curses.h. This makes reading keys +portable and easy to manage.</p> +<p>For example, if you call getch() like this</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> int ch; + + ch = getch();</font> +</pre></td> +</tr> +</table> +<p>getch() will wait for the user to press a key, (unless you +specified a timeout) and when user presses a key, the corresponding +integer is returned. Then you can check the value returned with the +constants defined in curses.h to match against the keys you +want.</p> +<p>The following code piece will do that job.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> if(ch == KEY_LEFT) + printw("Left arrow is pressed\n");</font> +</pre></td> +</tr> +</table> +<p>Let's write a small program which creates a menu which can be +navigated by up and down arrows.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="SIMPLEKEYEX" id="SIMPLEKEYEX">11.2. A +Simple Key Usage example</a></h3> +<div class="EXAMPLE"><a name="BSIKE" id="BSIKE"></a> +<p><b>Example 10. A Simple Key Usage example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <stdio.h> +#include <ncurses.h> + +#define WIDTH 30 +#define HEIGHT 10 + +int startx = 0; +int starty = 0; + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Exit", + }; +int n_choices = sizeof(choices) / sizeof(char *); +void print_menu(WINDOW *menu_win, int highlight); + +int main() +{ WINDOW *menu_win; + int highlight = 1; + int choice = 0; + int c; + + initscr(); + clear(); + noecho(); + cbreak(); /* Line buffering disabled. pass on everything */ + startx = (80 - WIDTH) / 2; + starty = (24 - HEIGHT) / 2; + + menu_win = newwin(HEIGHT, WIDTH, starty, startx); + keypad(menu_win, TRUE); + mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice"); + refresh(); + print_menu(menu_win, highlight); + while(1) + { c = wgetch(menu_win); + switch(c) + { case KEY_UP: + if(highlight == 1) + highlight = n_choices; + else + --highlight; + break; + case KEY_DOWN: + if(highlight == n_choices) + highlight = 1; + else + ++highlight; + break; + case 10: + choice = highlight; + break; + default: + mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c); + refresh(); + break; + } + print_menu(menu_win, highlight); + if(choice != 0) /* User did a choice come out of the infinite loop */ + break; + } + mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]); + clrtoeol(); + refresh(); + endwin(); + return 0; +} + + +void print_menu(WINDOW *menu_win, int highlight) +{ + int x, y, i; + + x = 2; + y = 2; + box(menu_win, 0, 0); + for(i = 0; i < n_choices; ++i) + { if(highlight == i + 1) /* High light the present choice */ + { wattron(menu_win, A_REVERSE); + mvwprintw(menu_win, y, x, "%s", choices[i]); + wattroff(menu_win, A_REVERSE); + } + else + mvwprintw(menu_win, y, x, "%s", choices[i]); + ++y; + } + wrefresh(menu_win); +} +</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing with +the mouse</a></h2> +<p>Now that you have seen how to get keys, lets do the same thing +from mouse. Usually each UI allows the user to interact with both +keyboard and mouse.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MOUSEBASICS" id="MOUSEBASICS">12.1. The +Basics</a></h3> +<p>Before you do any thing else, the events you want to receive +have to be enabled with <var class="LITERAL">mousemask()</var>.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> mousemask( mmask_t newmask, /* The events you want to listen to */ + mmask_t *oldmask) /* The old events mask */</font> +</pre></td> +</tr> +</table> +<p>The first parameter to above function is a bit mask of events +you would like to listen. By default, all the events are turned +off. The bit mask <var class="LITERAL">ALL_MOUSE_EVENTS</var> can +be used to get all the events.</p> +<p>The following are all the event masks:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> Name Description + --------------------------------------------------------------------- + BUTTON1_PRESSED mouse button 1 down + BUTTON1_RELEASED mouse button 1 up + BUTTON1_CLICKED mouse button 1 clicked + BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked + BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked + BUTTON2_PRESSED mouse button 2 down + BUTTON2_RELEASED mouse button 2 up + BUTTON2_CLICKED mouse button 2 clicked + BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked + BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked + BUTTON3_PRESSED mouse button 3 down + BUTTON3_RELEASED mouse button 3 up + BUTTON3_CLICKED mouse button 3 clicked + BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked + BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked + BUTTON4_PRESSED mouse button 4 down + BUTTON4_RELEASED mouse button 4 up + BUTTON4_CLICKED mouse button 4 clicked + BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked + BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked + BUTTON_SHIFT shift was down during button state change + BUTTON_CTRL control was down during button state change + BUTTON_ALT alt was down during button state change + ALL_MOUSE_EVENTS report all button state changes + REPORT_MOUSE_POSITION report mouse movement</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="GETTINGEVENTS" id="GETTINGEVENTS">12.2. +Getting the events</a></h3> +<p>Once a class of mouse events have been enabled, getch() class of +functions return KEY_MOUSE every time some mouse event happens. +Then the mouse event can be retrieved with <var class= +"LITERAL">getmouse()</var>.</p> +<p>The code approximately looks like this:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> MEVENT event; + + ch = getch(); + if(ch == KEY_MOUSE) + if(getmouse(&event) == OK) + . /* Do some thing with the event */ + . + .</font> +</pre></td> +</tr> +</table> +<p>getmouse() returns the event into the pointer given to it. It's +a structure which contains</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> typedef struct + { + short id; /* ID to distinguish multiple devices */ + int x, y, z; /* event coordinates */ + mmask_t bstate; /* button state bits */ + } </font> +</pre></td> +</tr> +</table> +<p>The <var class="LITERAL">bstate</var> is the main variable we +are interested in. It tells the button state of the mouse.</p> +<p>Then with a code snippet like the following, we can find out +what happened.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> if(event.bstate & BUTTON1_PRESSED) + printw("Left Button Pressed");</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MOUSETOGETHER" id="MOUSETOGETHER">12.3. +Putting it all Together</a></h3> +<p>That's pretty much interfacing with mouse. Let's create the same +menu and enable mouse interaction. To make things simpler, key +handling is removed.</p> +<div class="EXAMPLE"><a name="BMOME" id="BMOME"></a> +<p><b>Example 11. Access the menu with mouse !!!</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +#define WIDTH 30 +#define HEIGHT 10 + +int startx = 0; +int starty = 0; + +char *choices[] = { "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Exit", + }; + +int n_choices = sizeof(choices) / sizeof(char *); + +void print_menu(WINDOW *menu_win, int highlight); +void report_choice(int mouse_x, int mouse_y, int *p_choice); + +int main() +{ int c, choice = 0; + WINDOW *menu_win; + MEVENT event; + + /* Initialize curses */ + initscr(); + clear(); + noecho(); + cbreak(); //Line buffering disabled. pass on everything + + /* Try to put the window in the middle of screen */ + startx = (80 - WIDTH) / 2; + starty = (24 - HEIGHT) / 2; + + attron(A_REVERSE); + mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)"); + refresh(); + attroff(A_REVERSE); + + /* Print the menu for the first time */ + menu_win = newwin(HEIGHT, WIDTH, starty, startx); + print_menu(menu_win, 1); + /* Get all the mouse events */ + mousemask(ALL_MOUSE_EVENTS, NULL); + + while(1) + { c = wgetch(menu_win); + switch(c) + { case KEY_MOUSE: + if(getmouse(&event) == OK) + { /* When the user clicks left mouse button */ + if(event.bstate & BUTTON1_PRESSED) + { report_choice(event.x + 1, event.y + 1, &choice); + if(choice == -1) //Exit chosen + goto end; + mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]); + refresh(); + } + } + print_menu(menu_win, choice); + break; + } + } +end: + endwin(); + return 0; +} + + +void print_menu(WINDOW *menu_win, int highlight) +{ + int x, y, i; + + x = 2; + y = 2; + box(menu_win, 0, 0); + for(i = 0; i < n_choices; ++i) + { if(highlight == i + 1) + { wattron(menu_win, A_REVERSE); + mvwprintw(menu_win, y, x, "%s", choices[i]); + wattroff(menu_win, A_REVERSE); + } + else + mvwprintw(menu_win, y, x, "%s", choices[i]); + ++y; + } + wrefresh(menu_win); +} + +/* Report the choice according to mouse position */ +void report_choice(int mouse_x, int mouse_y, int *p_choice) +{ int i,j, choice; + + i = startx + 2; + j = starty + 3; + + for(choice = 0; choice < n_choices; ++choice) + if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice])) + { if(choice == n_choices - 1) + *p_choice = -1; + else + *p_choice = choice + 1; + break; + } +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MISCMOUSEFUNCS" id= +"MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3> +<p>The functions mouse_trafo() and wmouse_trafo() can be used to +convert to mouse co-ordinates to screen relative co-ordinates. See +curs_mouse(3X) man page for details.</p> +<p>The mouseinterval function sets the maximum time (in thousands +of a second) that can elapse between press and release events in +order for them to be recognized as a click. This function returns +the previous interval value. The default is one fifth of a +second.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen +Manipulation</a></h2> +<p>In this section, we will look into some functions, which allow +us to manage the screen efficiently and to write some fancy +programs. This is especially important in writing games.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx() +functions</a></h3> +<p>The function <var class="LITERAL">getyx()</var> can be used to +find out the present cursor co-ordinates. It will fill the values +of x and y co-ordinates in the arguments given to it. Since getyx() +is a macro you don't have to pass the address of the variables. It +can be called as</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> getyx(win, y, x); + /* win: window pointer + * y, x: y, x co-ordinates will be put into this variables + */</font> +</pre></td> +</tr> +</table> +<p>The function getparyx() gets the beginning co-ordinates of the +sub window relative to the main window. This is some times useful +to update a sub window. When designing fancy stuff like writing +multiple menus, it becomes difficult to store the menu positions, +their first option co-ordinates etc. A simple solution to this +problem, is to create menus in sub windows and later find the +starting co-ordinates of the menus by using getparyx().</p> +<p>The functions getbegyx() and getmaxyx() store current window's +beginning and maximum co-ordinates. These functions are useful in +the same way as above in managing the windows and sub windows +effectively.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="SCREENDUMP" id="SCREENDUMP">13.2. Screen +Dumping</a></h3> +<p>While writing games, some times it becomes necessary to store +the state of the screen and restore it back to the same state. The +function scr_dump() can be used to dump the screen contents to a +file given as an argument. Later it can be restored by scr_restore +function. These two simple functions can be used effectively to +maintain a fast moving game with changing scenarios.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="WINDOWDUMP" id="WINDOWDUMP">13.3. Window +Dumping</a></h3> +<p>To store and restore windows, the functions <var class= +"LITERAL">putwin()</var> and <var class="LITERAL">getwin()</var> +can be used. <var class="LITERAL">putwin()</var> puts the present +window state into a file, which can be later restored by +<var class="LITERAL">getwin()</var>.</p> +<p>The function <var class="LITERAL">copywin()</var> can be used to +copy a window completely onto another window. It takes the source +and destination windows as parameters and according to the +rectangle specified, it copies the rectangular region from source +to destination window. It's last parameter specifies whether to +overwrite or just overlay the contents on to the destination +window. If this argument is true, then the copying is +non-destructive.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous +features</a></h2> +<p>Now you know enough features to write a good curses program, +with all bells and whistles. There are some miscellaneous functions +which are useful in various cases. Let's go headlong into some of +those.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1. +curs_set()</a></h3> +<p>This function can be used to make the cursor invisible. The +parameter to this function should be</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> 0 : invisible or + 1 : normal or + 2 : very visible.</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2. +Temporarily Leaving Curses mode</a></h3> +<p>Some times you may want to get back to cooked mode (normal line +buffering mode) temporarily. In such a case you will first need to +save the tty modes with a call to <var class= +"LITERAL">def_prog_mode()</var> and then call <var class= +"LITERAL">endwin()</var> to end the curses mode. This will leave +you in the original tty mode. To get back to curses once you are +done, call <var class="LITERAL">reset_prog_mode()</var> . This +function returns the tty to the state stored by <var class= +"LITERAL">def_prog_mode()</var>. Then do refresh(), and you are +back to the curses mode. Here is an example showing the sequence of +things to be done.</p> +<div class="EXAMPLE"><a name="BTELE" id="BTELE"></a> +<p><b>Example 12. Temporarily Leaving Curses Mode</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +int main() +{ + initscr(); /* Start curses mode */ + printw("Hello World !!!\n"); /* Print Hello World */ + refresh(); /* Print it on to the real screen */ + def_prog_mode(); /* Save the tty modes */ + endwin(); /* End curses mode temporarily */ + system("/bin/sh"); /* Do whatever you like in cooked mode */ + reset_prog_mode(); /* Return to the previous tty mode*/ + /* stored by def_prog_mode() */ + refresh(); /* Do refresh() to restore the */ + /* Screen contents */ + printw("Another String\n"); /* Back to curses use the full */ + refresh(); /* capabilities of curses */ + endwin(); /* End curses mode */ + + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_ +variables</a></h3> +<p>If you have ever programmed in DOS, you know about those nifty +characters in extended character set. They are printable only on +some terminals. NCURSES functions like <var class= +"LITERAL">box()</var> use these characters. All these variables +start with ACS meaning alternative character set. You might have +noticed me using these characters in some of the programs above. +Here's an example showing all the characters.</p> +<div class="EXAMPLE"><a name="BACSVARS" id="BACSVARS"></a> +<p><b>Example 13. ACS Variables Example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <ncurses.h> + +int main() +{ + initscr(); + + printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n"); + printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n"); + printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n"); + printw("Tee pointing right "); addch(ACS_LTEE); printw("\n"); + printw("Tee pointing left "); addch(ACS_RTEE); printw("\n"); + printw("Tee pointing up "); addch(ACS_BTEE); printw("\n"); + printw("Tee pointing down "); addch(ACS_TTEE); printw("\n"); + printw("Horizontal line "); addch(ACS_HLINE); printw("\n"); + printw("Vertical line "); addch(ACS_VLINE); printw("\n"); + printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n"); + printw("Scan Line 1 "); addch(ACS_S1); printw("\n"); + printw("Scan Line 3 "); addch(ACS_S3); printw("\n"); + printw("Scan Line 7 "); addch(ACS_S7); printw("\n"); + printw("Scan Line 9 "); addch(ACS_S9); printw("\n"); + printw("Diamond "); addch(ACS_DIAMOND); printw("\n"); + printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n"); + printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n"); + printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n"); + printw("Bullet "); addch(ACS_BULLET); printw("\n"); + printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n"); + printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n"); + printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n"); + printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n"); + printw("Board of squares "); addch(ACS_BOARD); printw("\n"); + printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n"); + printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n"); + printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n"); + printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n"); + printw("Pi "); addch(ACS_PI); printw("\n"); + printw("Not equal "); addch(ACS_NEQUAL); printw("\n"); + printw("UK pound sign "); addch(ACS_STERLING); printw("\n"); + + refresh(); + getch(); + endwin(); + + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other +libraries</a></h2> +<p>Apart from the curses library, there are few text mode +libraries, which provide more functionality and a lot of features. +The following sections explain three standard libraries which are +usually distributed along with curses.</p> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel +Library</a></h2> +<p>Now that you are proficient in curses, you wanted to do some +thing big. You created a lot of overlapping windows to give a +professional windows-type look. Unfortunately, it soon becomes +difficult to manage these. The multiple refreshes, updates plunge +you into a nightmare. The overlapping windows create blotches, +whenever you forget to refresh the windows in the proper order.</p> +<p>Don't despair. There's an elegant solution provided in panels +library. In the words of developers of ncurses</p> +<p><em>When your interface design is such that windows may dive +deeper into the visibility stack or pop to the top at runtime, the +resulting book-keeping can be tedious and difficult to get right. +Hence the panels library.</em></p> +<p>If you have lot of overlapping windows, then panels library is +the way to go. It obviates the need of doing series of +wnoutrefresh(), doupdate() and relieves the burden of doing it +correctly(bottom up). The library maintains information about the +order of windows, their overlapping and update the screen properly. +So why wait? Let's take a close peek into panels.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PANELBASICS" id="PANELBASICS">16.1. The +Basics</a></h3> +<p>Panel object is a window that is implicitly treated as part of a +deck including all other panel objects. The deck is treated as a +stack with the top panel being completely visible and the other +panels may or may not be obscured according to their positions. So +the basic idea is to create a stack of overlapping panels and use +panels library to display them correctly. There is a function +similar to refresh() which, when called , displays panels in the +correct order. Functions are provided to hide or show panels, move +panels, change its size etc.. The overlapping problem is managed by +the panels library during all the calls to these functions.</p> +<p>The general flow of a panel program goes like this:</p> +<ol type="1"> +<li> +<p>Create the windows (with newwin()) to be attached to the +panels.</p> +</li> +<li> +<p>Create panels with the chosen visibility order. Stack them up +according to the desired visibility. The function new_panel() is +used to created panels.</p> +</li> +<li> +<p>Call update_panels() to write the panels to the virtual screen +in correct visibility order. Do a doupdate() to show it on the +screen.</p> +</li> +<li> +<p>Mainpulate the panels with show_panel(), hide_panel(), +move_panel() etc. Make use of helper functions like panel_hidden() +and panel_window(). Make use of user pointer to store custom data +for a panel. Use the functions set_panel_userptr() and +panel_userptr() to set and get the user pointer for a panel.</p> +</li> +<li> +<p>When you are done with the panel use del_panel() to delete the +panel.</p> +</li> +</ol> +<p>Let's make the concepts clear, with some programs. The following +is a simple program which creates 3 overlapping panels and shows +them on the screen.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="COMPILEPANELS" id="COMPILEPANELS">16.2. +Compiling With the Panels Library</a></h3> +<p>To use panels library functions, you have to include panel.h and +to link the program with panels library the flag -lpanel should be +added along with -lncurses in that order.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> #include <panel.h> + . + . + . + + compile and link: gcc <program file> -lpanel -lncurses</font> +</pre></td> +</tr> +</table> +<div class="EXAMPLE"><a name="PPASI" id="PPASI"></a> +<p><b>Example 14. Panel basics</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <panel.h> + +int main() +{ WINDOW *my_wins[3]; + PANEL *my_panels[3]; + int lines = 10, cols = 40, y = 2, x = 4, i; + + initscr(); + cbreak(); + noecho(); + + /* Create windows for the panels */ + my_wins[0] = newwin(lines, cols, y, x); + my_wins[1] = newwin(lines, cols, y + 1, x + 5); + my_wins[2] = newwin(lines, cols, y + 2, x + 10); + + /* + * Create borders around the windows so that you can see the effect + * of panels + */ + for(i = 0; i < 3; ++i) + box(my_wins[i], 0, 0); + + /* Attach a panel to each window */ /* Order is bottom up */ + my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ + my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ + my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ + + /* Update the stacking order. 2nd panel will be on top */ + update_panels(); + + /* Show it on the screen */ + doupdate(); + + getch(); + endwin(); +} +</span></font> +</pre></td> +</tr> +</table> +</div> +<p>As you can see, above program follows a simple flow as +explained. The windows are created with newwin() and then they are +attached to panels with new_panel(). As we attach one panel after +another, the stack of panels gets updated. To put them on screen +update_panels() and doupdate() are called.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PANELBROWSING" id="PANELBROWSING">16.3. +Panel Window Browsing</a></h3> +<p>A slightly complicated example is given below. This program +creates 3 windows which can be cycled through using tab. Have a +look at the code.</p> +<div class="EXAMPLE"><a name="PPABR" id="PPABR"></a> +<p><b>Example 15. Panel Window Browsing Example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <panel.h> + +#define NLINES 10 +#define NCOLS 40 + +void init_wins(WINDOW **wins, int n); +void win_show(WINDOW *win, char *label, int label_color); +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); + +int main() +{ WINDOW *my_wins[3]; + PANEL *my_panels[3]; + PANEL *top; + int ch; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize all the colors */ + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_GREEN, COLOR_BLACK); + init_pair(3, COLOR_BLUE, COLOR_BLACK); + init_pair(4, COLOR_CYAN, COLOR_BLACK); + + init_wins(my_wins, 3); + + /* Attach a panel to each window */ /* Order is bottom up */ + my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ + my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ + my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ + + /* Set up the user pointers to the next panel */ + set_panel_userptr(my_panels[0], my_panels[1]); + set_panel_userptr(my_panels[1], my_panels[2]); + set_panel_userptr(my_panels[2], my_panels[0]); + + /* Update the stacking order. 2nd panel will be on top */ + update_panels(); + + /* Show it on the screen */ + attron(COLOR_PAIR(4)); + mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); + attroff(COLOR_PAIR(4)); + doupdate(); + + top = my_panels[2]; + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case 9: + top = (PANEL *)panel_userptr(top); + top_panel(top); + break; + } + update_panels(); + doupdate(); + } + endwin(); + return 0; +} + +/* Put all the windows */ +void init_wins(WINDOW **wins, int n) +{ int x, y, i; + char label[80]; + + y = 2; + x = 10; + for(i = 0; i < n; ++i) + { wins[i] = newwin(NLINES, NCOLS, y, x); + sprintf(label, "Window Number %d", i + 1); + win_show(wins[i], label, i + 1); + y += 3; + x += 7; + } +} + +/* Show the window with a border and a label */ +void win_show(WINDOW *win, char *label, int label_color) +{ int startx, starty, height, width; + + getbegyx(win, starty, startx); + getmaxyx(win, height, width); + + box(win, 0, 0); + mvwaddch(win, 2, 0, ACS_LTEE); + mvwhline(win, 2, 1, ACS_HLINE, width - 2); + mvwaddch(win, 2, width - 1, ACS_RTEE); + + print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); +} + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + wattron(win, color); + mvwprintw(win, y, x, "%s", string); + wattroff(win, color); + refresh(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="USERPTRUSING" id="USERPTRUSING">16.4. +Using User Pointers</a></h3> +<p>In the above example I used user pointers to find out the next +window in the cycle. We can attach custom information to the panel +by specifying a user pointer, which can point to any information +you want to store. In this case I stored the pointer to the next +panel in the cycle. User pointer for a panel can be set with the +function <var class="LITERAL">set_panel_userptr()</var>. It can be +accessed using the function <var class= +"LITERAL">panel_userptr()</var> which will return the user pointer +for the panel given as argument. After finding the next panel in +the cycle It's brought to the top by the function top_panel(). This +function brings the panel given as argument to the top of the panel +stack.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PANELMOVERESIZE" id= +"PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3> +<p>The function <var class="LITERAL">move_panel()</var> can be used +to move a panel to the desired location. It does not change the +position of the panel in the stack. Make sure that you use +move_panel() instead mvwin() on the window associated with the +panel.</p> +<p>Resizing a panel is slightly complex. There is no straight +forward function just to resize the window associated with a panel. +A solution to resize a panel is to create a new window with the +desired sizes, change the window associated with the panel using +replace_panel(). Don't forget to delete the old window. The window +associated with a panel can be found by using the function +panel_window().</p> +<p>The following program shows these concepts, in supposedly simple +program. You can cycle through the window with <TAB> as +usual. To resize or move the active panel press 'r' for resize 'm' +for moving. Then use arrow keys to resize or move it to the desired +way and press enter to end your resizing or moving. This example +makes use of user data to get the required data to do the +operations.</p> +<div class="EXAMPLE"><a name="PPARE" id="PPARE"></a> +<p><b>Example 16. Panel Moving and Resizing example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <panel.h> + +typedef struct _PANEL_DATA { + int x, y, w, h; + char label[80]; + int label_color; + PANEL *next; +}PANEL_DATA; + +#define NLINES 10 +#define NCOLS 40 + +void init_wins(WINDOW **wins, int n); +void win_show(WINDOW *win, char *label, int label_color); +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); +void set_user_ptrs(PANEL **panels, int n); + +int main() +{ WINDOW *my_wins[3]; + PANEL *my_panels[3]; + PANEL_DATA *top; + PANEL *stack_top; + WINDOW *temp_win, *old_win; + int ch; + int newx, newy, neww, newh; + int size = FALSE, move = FALSE; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize all the colors */ + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_GREEN, COLOR_BLACK); + init_pair(3, COLOR_BLUE, COLOR_BLACK); + init_pair(4, COLOR_CYAN, COLOR_BLACK); + + init_wins(my_wins, 3); + + /* Attach a panel to each window */ /* Order is bottom up */ + my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ + my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ + my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ + + set_user_ptrs(my_panels, 3); + /* Update the stacking order. 2nd panel will be on top */ + update_panels(); + + /* Show it on the screen */ + attron(COLOR_PAIR(4)); + mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing"); + mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); + attroff(COLOR_PAIR(4)); + doupdate(); + + stack_top = my_panels[2]; + top = (PANEL_DATA *)panel_userptr(stack_top); + newx = top->x; + newy = top->y; + neww = top->w; + newh = top->h; + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case 9: /* Tab */ + top = (PANEL_DATA *)panel_userptr(stack_top); + top_panel(top->next); + stack_top = top->next; + top = (PANEL_DATA *)panel_userptr(stack_top); + newx = top->x; + newy = top->y; + neww = top->w; + newh = top->h; + break; + case 'r': /* Re-Size*/ + size = TRUE; + attron(COLOR_PAIR(4)); + mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing"); + refresh(); + attroff(COLOR_PAIR(4)); + break; + case 'm': /* Move */ + attron(COLOR_PAIR(4)); + mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving"); + refresh(); + attroff(COLOR_PAIR(4)); + move = TRUE; + break; + case KEY_LEFT: + if(size == TRUE) + { --newx; + ++neww; + } + if(move == TRUE) + --newx; + break; + case KEY_RIGHT: + if(size == TRUE) + { ++newx; + --neww; + } + if(move == TRUE) + ++newx; + break; + case KEY_UP: + if(size == TRUE) + { --newy; + ++newh; + } + if(move == TRUE) + --newy; + break; + case KEY_DOWN: + if(size == TRUE) + { ++newy; + --newh; + } + if(move == TRUE) + ++newy; + break; + case 10: /* Enter */ + move(LINES - 4, 0); + clrtoeol(); + refresh(); + if(size == TRUE) + { old_win = panel_window(stack_top); + temp_win = newwin(newh, neww, newy, newx); + replace_panel(stack_top, temp_win); + win_show(temp_win, top->label, top->label_color); + delwin(old_win); + size = FALSE; + } + if(move == TRUE) + { move_panel(stack_top, newy, newx); + move = FALSE; + } + break; + + } + attron(COLOR_PAIR(4)); + mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing"); + mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); + attroff(COLOR_PAIR(4)); + refresh(); + update_panels(); + doupdate(); + } + endwin(); + return 0; +} + +/* Put all the windows */ +void init_wins(WINDOW **wins, int n) +{ int x, y, i; + char label[80]; + + y = 2; + x = 10; + for(i = 0; i < n; ++i) + { wins[i] = newwin(NLINES, NCOLS, y, x); + sprintf(label, "Window Number %d", i + 1); + win_show(wins[i], label, i + 1); + y += 3; + x += 7; + } +} + +/* Set the PANEL_DATA structures for individual panels */ +void set_user_ptrs(PANEL **panels, int n) +{ PANEL_DATA *ptrs; + WINDOW *win; + int x, y, w, h, i; + char temp[80]; + + ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA)); + + for(i = 0;i < n; ++i) + { win = panel_window(panels[i]); + getbegyx(win, y, x); + getmaxyx(win, h, w); + ptrs[i].x = x; + ptrs[i].y = y; + ptrs[i].w = w; + ptrs[i].h = h; + sprintf(temp, "Window Number %d", i + 1); + strcpy(ptrs[i].label, temp); + ptrs[i].label_color = i + 1; + if(i + 1 == n) + ptrs[i].next = panels[0]; + else + ptrs[i].next = panels[i + 1]; + set_panel_userptr(panels[i], &ptrs[i]); + } +} + +/* Show the window with a border and a label */ +void win_show(WINDOW *win, char *label, int label_color) +{ int startx, starty, height, width; + + getbegyx(win, starty, startx); + getmaxyx(win, height, width); + + box(win, 0, 0); + mvwaddch(win, 2, 0, ACS_LTEE); + mvwhline(win, 2, 1, ACS_HLINE, width - 2); + mvwaddch(win, 2, width - 1, ACS_RTEE); + + print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); +} + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + wattron(win, color); + mvwprintw(win, y, x, "%s", string); + wattroff(win, color); + refresh(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>Concentrate on the main while loop. Once it finds out the type +of key pressed, it takes appropriate action. If 'r' is pressed +resizing mode is started. After this the new sizes are updated as +the user presses the arrow keys. When the user presses +<ENTER> present selection ends and panel is resized by using +the concept explained. While in resizing mode the program doesn't +show how the window is getting resized. It's left as an exercise to +the reader to print a dotted border while it gets resized to a new +position.</p> +<p>When the user presses 'm' the move mode starts. This is a bit +simpler than resizing. As the arrow keys are pressed the new +position is updated and pressing of <ENTER> causes the panel +to be moved by calling the function move_panel().</p> +<p>In this program the user data which is represented as +PANEL_DATA, plays very important role in finding the associated +information with a panel. As written in the comments, the +PANEL_DATA stores the panel sizes, label, label color and a pointer +to the next panel in the cycle.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PANELSHOWHIDE" id="PANELSHOWHIDE">16.6. +Hiding and Showing Panels</a></h3> +<p>A Panel can be hidden by using the function hide_panel(). This +function merely removes it form the stack of panels, thus hiding it +on the screen once you do update_panels() and doupdate(). It +doesn't destroy the PANEL structure associated with the hidden +panel. It can be shown again by using the show_panel() +function.</p> +<p>The following program shows the hiding of panels. Press 'a' or +'b' or 'c' to show or hide first, second and third windows +respectively. It uses a user data with a small variable hide, which +keeps track of whether the window is hidden or not. For some reason +the function <var class="LITERAL">panel_hidden()</var> which tells +whether a panel is hidden or not is not working. A bug report was +also presented by Michael Andres <a href= +"http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/" +target="_top">here</a></p> +<div class="EXAMPLE"><a name="PPAHI" id="PPAHI"></a> +<p><b>Example 17. Panel Hiding and Showing example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <panel.h> + +typedef struct _PANEL_DATA { + int hide; /* TRUE if panel is hidden */ +}PANEL_DATA; + +#define NLINES 10 +#define NCOLS 40 + +void init_wins(WINDOW **wins, int n); +void win_show(WINDOW *win, char *label, int label_color); +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); + +int main() +{ WINDOW *my_wins[3]; + PANEL *my_panels[3]; + PANEL_DATA panel_datas[3]; + PANEL_DATA *temp; + int ch; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize all the colors */ + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_GREEN, COLOR_BLACK); + init_pair(3, COLOR_BLUE, COLOR_BLACK); + init_pair(4, COLOR_CYAN, COLOR_BLACK); + + init_wins(my_wins, 3); + + /* Attach a panel to each window */ /* Order is bottom up */ + my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ + my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ + my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ + + /* Initialize panel datas saying that nothing is hidden */ + panel_datas[0].hide = FALSE; + panel_datas[1].hide = FALSE; + panel_datas[2].hide = FALSE; + + set_panel_userptr(my_panels[0], &panel_datas[0]); + set_panel_userptr(my_panels[1], &panel_datas[1]); + set_panel_userptr(my_panels[2], &panel_datas[2]); + + /* Update the stacking order. 2nd panel will be on top */ + update_panels(); + + /* Show it on the screen */ + attron(COLOR_PAIR(4)); + mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)"); + mvprintw(LINES - 2, 0, "F1 to Exit"); + + attroff(COLOR_PAIR(4)); + doupdate(); + + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case 'a': + temp = (PANEL_DATA *)panel_userptr(my_panels[0]); + if(temp->hide == FALSE) + { hide_panel(my_panels[0]); + temp->hide = TRUE; + } + else + { show_panel(my_panels[0]); + temp->hide = FALSE; + } + break; + case 'b': + temp = (PANEL_DATA *)panel_userptr(my_panels[1]); + if(temp->hide == FALSE) + { hide_panel(my_panels[1]); + temp->hide = TRUE; + } + else + { show_panel(my_panels[1]); + temp->hide = FALSE; + } + break; + case 'c': + temp = (PANEL_DATA *)panel_userptr(my_panels[2]); + if(temp->hide == FALSE) + { hide_panel(my_panels[2]); + temp->hide = TRUE; + } + else + { show_panel(my_panels[2]); + temp->hide = FALSE; + } + break; + } + update_panels(); + doupdate(); + } + endwin(); + return 0; +} + +/* Put all the windows */ +void init_wins(WINDOW **wins, int n) +{ int x, y, i; + char label[80]; + + y = 2; + x = 10; + for(i = 0; i < n; ++i) + { wins[i] = newwin(NLINES, NCOLS, y, x); + sprintf(label, "Window Number %d", i + 1); + win_show(wins[i], label, i + 1); + y += 3; + x += 7; + } +} + +/* Show the window with a border and a label */ +void win_show(WINDOW *win, char *label, int label_color) +{ int startx, starty, height, width; + + getbegyx(win, starty, startx); + getmaxyx(win, height, width); + + box(win, 0, 0); + mvwaddch(win, 2, 0, ACS_LTEE); + mvwhline(win, 2, 1, ACS_HLINE, width - 2); + mvwaddch(win, 2, width - 1, ACS_RTEE); + + print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); +} + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + wattron(win, color); + mvwprintw(win, y, x, "%s", string); + wattroff(win, color); + refresh(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PANELABOVE" id="PANELABOVE">16.7. +panel_above() and panel_below() Functions</a></h3> +<p>The functions <var class="LITERAL">panel_above()</var> and +<var class="LITERAL">panel_below()</var> can be used to find out +the panel above and below a panel. If the argument to these +functions is NULL, then they return a pointer to bottom panel and +top panel respectively.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus +Library</a></h2> +<p>The menus library provides a nice extension to basic curses, +through which you can create menus. It provides a set of functions +to create menus. But they have to be customized to give a nicer +look, with colors etc. Let's get into the details.</p> +<p>A menu is a screen display that assists the user to choose some +subset of a given set of items. To put it simple, a menu is a +collection of items from which one or more items can be chosen. +Some readers might not be aware of multiple item selection +capability. Menu library provides functionality to write menus from +which the user can chose more than one item as the preferred +choice. This is dealt with in a later section. Now it is time for +some rudiments.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MENUBASICS" id="MENUBASICS">17.1. The +Basics</a></h3> +<p>To create menus, you first create items, and then post the menu +to the display. After that, all the processing of user responses is +done in an elegant function menu_driver() which is the work horse +of any menu program.</p> +<p>The general flow of control of a menu program looks like +this.</p> +<ol type="1"> +<li> +<p>Initialize curses</p> +</li> +<li> +<p>Create items using new_item(). You can specify a name and +description for the items.</p> +</li> +<li> +<p>Create the menu with new_menu() by specifying the items to be +attached with.</p> +</li> +<li> +<p>Post the menu with menu_post() and refresh the screen.</p> +</li> +<li> +<p>Process the user requests with a loop and do necessary updates +to menu with menu_driver.</p> +</li> +<li> +<p>Unpost the menu with menu_unpost()</p> +</li> +<li> +<p>Free the memory allocated to menu by free_menu()</p> +</li> +<li> +<p>Free the memory allocated to the items with free_item()</p> +</li> +<li> +<p>End curses</p> +</li> +</ol> +<p>Let's see a program which prints a simple menu and updates the +current selection with up, down arrows.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="COMPILEMENUS" id="COMPILEMENUS">17.2. +Compiling With the Menu Library</a></h3> +<p>To use menu library functions, you have to include menu.h and to +link the program with menu library the flag -lmenu should be added +along with -lncurses in that order.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> #include <menu.h> + . + . + . + + compile and link: gcc <program file> -lmenu -lncurses</font> +</pre></td> +</tr> +</table> +<div class="EXAMPLE"><a name="MMESI" id="MMESI"></a> +<p><b>Example 18. Menu Basics</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <curses.h> +#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Exit", + }; + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + int n_choices, i; + ITEM *cur_item; + + + initscr(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); + + for(i = 0; i < n_choices; ++i) + my_items[i] = new_item(choices[i], choices[i]); + my_items[n_choices] = (ITEM *)NULL; + + my_menu = new_menu((ITEM **)my_items); + mvprintw(LINES - 2, 0, "F1 to Exit"); + post_menu(my_menu); + refresh(); + + while((c = getch()) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + } + } + + free_item(my_items[0]); + free_item(my_items[1]); + free_menu(my_menu); + endwin(); +} + </span></font> +</pre></td> +</tr> +</table> +</div> +<p>This program demonstrates the basic concepts involved in +creating a menu using menus library. First we create the items +using new_item() and then attach them to the menu with new_menu() +function. After posting the menu and refreshing the screen, the +main processing loop starts. It reads user input and takes +corresponding action. The function menu_driver() is the main work +horse of the menu system. The second parameter to this function +tells what's to be done with the menu. According to the parameter, +menu_driver() does the corresponding task. The value can be either +a menu navigational request, an ascii character, or a KEY_MOUSE +special key associated with a mouse event.</p> +<p>The menu_driver accepts following navigational requests.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> REQ_LEFT_ITEM Move left to an item. + REQ_RIGHT_ITEM Move right to an item. + REQ_UP_ITEM Move up to an item. + REQ_DOWN_ITEM Move down to an item. + REQ_SCR_ULINE Scroll up a line. + REQ_SCR_DLINE Scroll down a line. + REQ_SCR_DPAGE Scroll down a page. + REQ_SCR_UPAGE Scroll up a page. + REQ_FIRST_ITEM Move to the first item. + REQ_LAST_ITEM Move to the last item. + REQ_NEXT_ITEM Move to the next item. + REQ_PREV_ITEM Move to the previous item. + REQ_TOGGLE_ITEM Select/deselect an item. + REQ_CLEAR_PATTERN Clear the menu pattern buffer. + REQ_BACK_PATTERN Delete the previous character from the pattern buffer. + REQ_NEXT_MATCH Move to the next item matching the pattern match. + REQ_PREV_MATCH Move to the previous item matching the pattern match. </font> +</pre></td> +</tr> +</table> +<p>Don't get overwhelmed by the number of options. We will see them +slowly one after another. The options of interest in this example +are REQ_UP_ITEM and REQ_DOWN_ITEM. These two options when passed to +menu_driver, menu driver updates the current item to one item up or +down respectively.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MENUDRIVER" id="MENUDRIVER">17.3. Menu +Driver: The work horse of the menu system</a></h3> +<p>As you have seen in the above example, menu_driver plays an +important role in updating the menu. It is very important to +understand various options it takes and what they do. As explained +above, the second parameter to menu_driver() can be either a +navigational request, a printable character or a KEY_MOUSE key. +Let's dissect the different navigational requests.</p> +<ul> +<li> +<p><em>REQ_LEFT_ITEM and REQ_RIGHT_ITEM</em></p> +<p>A Menu can be displayed with multiple columns for more than one +item. This can be done by using the <var class= +"LITERAL">menu_format()</var>function. When a multi columnar menu +is displayed these requests cause the menu driver to move the +current selection to left or right.</p> +</li> +<li> +<p><em>REQ_UP_ITEM and REQ_DOWN_ITEM</em></p> +<p>These two options you have seen in the above example. These +options when given, makes the menu_driver to move the current +selection to an item up or down.</p> +</li> +<li> +<p><em>REQ_SCR_* options</em></p> +<p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE, REQ_SCR_DPAGE, +REQ_SCR_UPAGE are related to scrolling. If all the items in the +menu cannot be displayed in the menu sub window, then the menu is +scrollable. These requests can be given to the menu_driver to do +the scrolling either one line up, down or one page down or up +respectively.</p> +</li> +<li> +<p><em>REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM and +REQ_PREV_ITEM</em></p> +<p>These requests are self explanatory.</p> +</li> +<li> +<p><em>REQ_TOGGLE_ITEM</em></p> +<p>This request when given, toggles the present selection. This +option is to be used only in a multi valued menu. So to use this +request the option O_ONEVALUE must be off. This option can be made +off or on with set_menu_opts().</p> +</li> +<li> +<p><em>Pattern Requests</em></p> +<p>Every menu has an associated pattern buffer, which is used to +find the nearest match to the ascii characters entered by the user. +Whenever ascii characters are given to menu_driver, it puts in to +the pattern buffer. It also tries to find the nearest match to the +pattern in the items list and moves current selection to that item. +The request REQ_CLEAR_PATTERN clears the pattern buffer. The +request REQ_BACK_PATTERN deletes the previous character in the +pattern buffer. In case the pattern matches more than one item then +the matched items can be cycled through REQ_NEXT_MATCH and +REQ_PREV_MATCH which move the current selection to the next and +previous matches respectively.</p> +</li> +<li> +<p><em>Mouse Requests</em></p> +<p>In case of KEY_MOUSE requests, according to the mouse position +an action is taken accordingly. The action to be taken is explained +in the man page as,</p> +<table border="0" bgcolor="#E0E0E0" width="90%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"><em> If the second argument is the KEY_MOUSE special key, the + associated mouse event is translated into one of the above + pre-defined requests. Currently only clicks in the user + window (e.g. inside the menu display area or the decora­ + tion window) are handled. If you click above the display + region of the menu, a REQ_SCR_ULINE is generated, if you + doubleclick a REQ_SCR_UPAGE is generated and if you + tripleclick a REQ_FIRST_ITEM is generated. If you click + below the display region of the menu, a REQ_SCR_DLINE is + generated, if you doubleclick a REQ_SCR_DPAGE is generated + and if you tripleclick a REQ_LAST_ITEM is generated. If + you click at an item inside the display area of the menu, + the menu cursor is positioned to that item.</em></font> +</pre></td> +</tr> +</table> +</li> +</ul> +<p>Each of the above requests will be explained in the following +lines with several examples whenever appropriate.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MENUWINDOWS" id="MENUWINDOWS">17.4. Menu +Windows</a></h3> +<p>Every menu created is associated with a window and a sub window. +The menu window displays any title or border associated with the +menu. The menu sub window displays the menu items currently +available for selection. But we didn't specify any window or sub +window in the simple example. When a window is not specified, +stdscr is taken as the main window, and then menu system calculates +the sub window size required for the display of items. Then items +are displayed in the calculated sub window. So let's play with +these windows and display a menu with a border and a title.</p> +<div class="EXAMPLE"><a name="MMEWI" id="MMEWI"></a> +<p><b>Example 19. Menu Windows Usage example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Exit", + (char *)NULL, + }; +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + WINDOW *my_menu_win; + int n_choices, i; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + init_pair(1, COLOR_RED, COLOR_BLACK); + + /* Create items */ + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); + for(i = 0; i < n_choices; ++i) + my_items[i] = new_item(choices[i], choices[i]); + + /* Crate menu */ + my_menu = new_menu((ITEM **)my_items); + + /* Create the window to be associated with the menu */ + my_menu_win = newwin(10, 40, 4, 4); + keypad(my_menu_win, TRUE); + + /* Set main window and sub window */ + set_menu_win(my_menu, my_menu_win); + set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1)); + + /* Set menu mark to the string " * " */ + set_menu_mark(my_menu, " * "); + + /* Print a border around the main window and print a title */ + box(my_menu_win, 0, 0); + print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1)); + mvwaddch(my_menu_win, 2, 0, ACS_LTEE); + mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38); + mvwaddch(my_menu_win, 2, 39, ACS_RTEE); + mvprintw(LINES - 2, 0, "F1 to exit"); + refresh(); + + /* Post the menu */ + post_menu(my_menu); + wrefresh(my_menu_win); + + while((c = wgetch(my_menu_win)) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + } + wrefresh(my_menu_win); + } + + /* Unpost and free all the memory taken up */ + unpost_menu(my_menu); + free_menu(my_menu); + for(i = 0; i < n_choices; ++i) + free_item(my_items[i]); + endwin(); +} + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + wattron(win, color); + mvwprintw(win, y, x, "%s", string); + wattroff(win, color); + refresh(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>This example creates a menu with a title, border, a fancy line +separating title and the items. As you can see, in order to attach +a window to a menu the function set_menu_win() has to be used. Then +we attach the sub window also. This displays the items in the sub +window. You can also set the mark string which gets displayed to +the left of the selected item with set_menu_mark().</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="SCROLLMENUS" id="SCROLLMENUS">17.5. +Scrolling Menus</a></h3> +<p>If the sub window given for a window is not big enough to show +all the items, then the menu will be scrollable. When you are on +the last item in the present list, if you send REQ_DOWN_ITEM, it +gets translated into REQ_SCR_DLINE and the menu scrolls by one +item. You can manually give REQ_SCR_ operations to do scrolling. +Let's see how it can be done.</p> +<div class="EXAMPLE"><a name="MMESC" id="MMESC"></a> +<p><b>Example 20. Scrolling Menus example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <curses.h> +#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Choice 5", + "Choice 6", + "Choice 7", + "Choice 8", + "Choice 9", + "Choice 10", + "Exit", + (char *)NULL, + }; +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + WINDOW *my_menu_win; + int n_choices, i; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_CYAN, COLOR_BLACK); + + /* Create items */ + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); + for(i = 0; i < n_choices; ++i) + my_items[i] = new_item(choices[i], choices[i]); + + /* Crate menu */ + my_menu = new_menu((ITEM **)my_items); + + /* Create the window to be associated with the menu */ + my_menu_win = newwin(10, 40, 4, 4); + keypad(my_menu_win, TRUE); + + /* Set main window and sub window */ + set_menu_win(my_menu, my_menu_win); + set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1)); + set_menu_format(my_menu, 5, 1); + + /* Set menu mark to the string " * " */ + set_menu_mark(my_menu, " * "); + + /* Print a border around the main window and print a title */ + box(my_menu_win, 0, 0); + print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1)); + mvwaddch(my_menu_win, 2, 0, ACS_LTEE); + mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38); + mvwaddch(my_menu_win, 2, 39, ACS_RTEE); + + /* Post the menu */ + post_menu(my_menu); + wrefresh(my_menu_win); + + attron(COLOR_PAIR(2)); + mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items"); + mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)"); + attroff(COLOR_PAIR(2)); + refresh(); + + while((c = wgetch(my_menu_win)) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + case KEY_NPAGE: + menu_driver(my_menu, REQ_SCR_DPAGE); + break; + case KEY_PPAGE: + menu_driver(my_menu, REQ_SCR_UPAGE); + break; + } + wrefresh(my_menu_win); + } + + /* Unpost and free all the memory taken up */ + unpost_menu(my_menu); + free_menu(my_menu); + for(i = 0; i < n_choices; ++i) + free_item(my_items[i]); + endwin(); +} + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + wattron(win, color); + mvwprintw(win, y, x, "%s", string); + wattroff(win, color); + refresh(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>This program is self-explanatory. In this example the number of +choices has been increased to ten, which is larger than our sub +window size which can hold 6 items. This message has to be +explicitly conveyed to the menu system with the function +set_menu_format(). In here we specify the number of rows and +columns we want to be displayed for a single page. We can specify +any number of items to be shown, in the rows variables, if it is +less than the height of the sub window. If the key pressed by the +user is a PAGE UP or PAGE DOWN, the menu is scrolled a page due to +the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE) given to +menu_driver().</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MULTICOLUMN" id="MULTICOLUMN">17.6. +Multi Columnar Menus</a></h3> +<p>In the above example you have seen how to use the function +set_menu_format(). I didn't mention what the cols variable (third +parameter) does. Well, If your sub window is wide enough, you can +opt to display more than one item per row. This can be specified in +the cols variable. To make things simpler, the following example +doesn't show descriptions for the items.</p> +<div class="EXAMPLE"><a name="MMEMUCO" id="MMEMUCO"></a> +<p><b>Example 21. Milt Columnar Menus Example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <curses.h> +#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5", + "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10", + "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15", + "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20", + "Exit", + (char *)NULL, + }; + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + WINDOW *my_menu_win; + int n_choices, i; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_CYAN, COLOR_BLACK); + + /* Create items */ + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); + for(i = 0; i < n_choices; ++i) + my_items[i] = new_item(choices[i], choices[i]); + + /* Crate menu */ + my_menu = new_menu((ITEM **)my_items); + + /* Set menu option not to show the description */ + menu_opts_off(my_menu, O_SHOWDESC); + + /* Create the window to be associated with the menu */ + my_menu_win = newwin(10, 70, 4, 4); + keypad(my_menu_win, TRUE); + + /* Set main window and sub window */ + set_menu_win(my_menu, my_menu_win); + set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1)); + set_menu_format(my_menu, 5, 3); + set_menu_mark(my_menu, " * "); + + /* Print a border around the main window and print a title */ + box(my_menu_win, 0, 0); + + attron(COLOR_PAIR(2)); + mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll"); + mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)"); + attroff(COLOR_PAIR(2)); + refresh(); + + /* Post the menu */ + post_menu(my_menu); + wrefresh(my_menu_win); + + while((c = wgetch(my_menu_win)) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + case KEY_LEFT: + menu_driver(my_menu, REQ_LEFT_ITEM); + break; + case KEY_RIGHT: + menu_driver(my_menu, REQ_RIGHT_ITEM); + break; + case KEY_NPAGE: + menu_driver(my_menu, REQ_SCR_DPAGE); + break; + case KEY_PPAGE: + menu_driver(my_menu, REQ_SCR_UPAGE); + break; + } + wrefresh(my_menu_win); + } + + /* Unpost and free all the memory taken up */ + unpost_menu(my_menu); + free_menu(my_menu); + for(i = 0; i < n_choices; ++i) + free_item(my_items[i]); + endwin(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>Watch the function call to set_menu_format(). It specifies the +number of columns to be 3, thus displaying 3 items per row. We have +also switched off the showing descriptions with the function +menu_opts_off(). There are couple of functions set_menu_opts(), +menu_opts_on() and menu_opts() which can be used to manipulate menu +options. The following menu options can be specified.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> O_ONEVALUE + Only one item can be selected for this menu. + + O_SHOWDESC + Display the item descriptions when the menu is + posted. + + O_ROWMAJOR + Display the menu in row-major order. + + O_IGNORECASE + Ignore the case when pattern-matching. + + O_SHOWMATCH + Move the cursor to within the item name while pat­ + tern-matching. + + O_NONCYCLIC + Don't wrap around next-item and previous-item, + requests to the other end of the menu.</font> +</pre></td> +</tr> +</table> +<p>All options are on by default. You can switch specific +attributes on or off with menu_opts_on() and menu_opts_off() +functions. You can also use set_menu_opts() to directly specify the +options. The argument to this function should be a OR ed value of +some of those above constants. The function menu_opts() can be used +to find out a menu's present options.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MULTIVALUEMENUS" id= +"MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3> +<p>You might be wondering what if you switch off the option +O_ONEVALUE. Then the menu becomes multi-valued. That means you can +select more than one item. This brings us to the request +REQ_TOGGLE_ITEM. Let's see it in action.</p> +<div class="EXAMPLE"><a name="MMETO" id="MMETO"></a> +<p><b>Example 22. Multi Valued Menus example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <curses.h> +#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Choice 5", + "Choice 6", + "Choice 7", + "Exit", + }; + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + int n_choices, i; + ITEM *cur_item; + + /* Initialize curses */ + initscr(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize items */ + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); + for(i = 0; i < n_choices; ++i) + my_items[i] = new_item(choices[i], choices[i]); + my_items[n_choices] = (ITEM *)NULL; + + my_menu = new_menu((ITEM **)my_items); + + /* Make the menu multi valued */ + menu_opts_off(my_menu, O_ONEVALUE); + + mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item."); + mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)"); + post_menu(my_menu); + refresh(); + + while((c = getch()) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + case ' ': + menu_driver(my_menu, REQ_TOGGLE_ITEM); + break; + case 10: /* Enter */ + { char temp[200]; + ITEM **items; + + items = menu_items(my_menu); + temp[0] = '\0'; + for(i = 0; i < item_count(my_menu); ++i) + if(item_value(items[i]) == TRUE) + { strcat(temp, item_name(items[i])); + strcat(temp, " "); + } + move(20, 0); + clrtoeol(); + mvprintw(20, 0, temp); + refresh(); + } + break; + } + } + + free_item(my_items[0]); + free_item(my_items[1]); + free_menu(my_menu); + endwin(); +} + </span></font> +</pre></td> +</tr> +</table> +</div> +<p>Whew, A lot of new functions. Let's take them one after another. +Firstly, the REQ_TOGGLE_ITEM. In a multi-valued menu, the user +should be allowed to select or un select more than one item. The +request REQ_TOGGLE_ITEM toggles the present selection. In this case +when space is pressed REQ_TOGGLE_ITEM request is sent to +menu_driver to achieve the result.</p> +<p>Now when the user presses <ENTER> we show the items he +presently selected. First we find out the items associated with the +menu using the function menu_items(). Then we loop through the +items to find out if the item is selected or not. The function +item_value() returns TRUE if an item is selected. The function +item_count() returns the number of items in the menu. The item name +can be found with item_name(). You can also find the description +associated with an item using item_description().</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu +Options</a></h3> +<p>Well, by this time you must be itching for some difference in +your menu, with lots of functionality. I know. You want Colors !!!. +You want to create nice menus similar to those text mode <a href= +"http://www.jersey.net/~debinjoe/games/" target="_top">dos +games</a>. The functions set_menu_fore() and set_menu_back() can be +used to change the attribute of the selected item and unselected +item. The names are misleading. They don't change menu's foreground +or background which would have been useless.</p> +<p>The function set_menu_grey() can be used to set the display +attribute for the non-selectable items in the menu. This brings us +to the interesting option for an item the one and only +O_SELECTABLE. We can turn it off by the function item_opts_off() +and after that that item is not selectable. It's like a grayed item +in those fancy windows menus. Let's put these concepts in practice +with this example</p> +<div class="EXAMPLE"><a name="MMEAT" id="MMEAT"></a> +<p><b>Example 23. Menu Options example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Choice 5", + "Choice 6", + "Choice 7", + "Exit", + }; + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + int n_choices, i; + ITEM *cur_item; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_GREEN, COLOR_BLACK); + init_pair(3, COLOR_MAGENTA, COLOR_BLACK); + + /* Initialize items */ + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); + for(i = 0; i < n_choices; ++i) + my_items[i] = new_item(choices[i], choices[i]); + my_items[n_choices] = (ITEM *)NULL; + item_opts_off(my_items[3], O_SELECTABLE); + item_opts_off(my_items[6], O_SELECTABLE); + + /* Create menu */ + my_menu = new_menu((ITEM **)my_items); + + /* Set fore ground and back ground of the menu */ + set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE); + set_menu_back(my_menu, COLOR_PAIR(2)); + set_menu_grey(my_menu, COLOR_PAIR(3)); + + /* Post the menu */ + mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected"); + mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)"); + post_menu(my_menu); + refresh(); + + while((c = getch()) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + case 10: /* Enter */ + move(20, 0); + clrtoeol(); + mvprintw(20, 0, "Item selected is : %s", + item_name(current_item(my_menu))); + pos_menu_cursor(my_menu); + break; + } + } + unpost_menu(my_menu); + for(i = 0; i < n_choices; ++i) + free_item(my_items[i]); + free_menu(my_menu); + endwin(); +} + </span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MENUUSERPTR" id="MENUUSERPTR">17.9. The +useful User Pointer</a></h3> +<p>We can associate a user pointer with each item in the menu. It +works the same way as user pointer in panels. It's not touched by +menu system. You can store any thing you like in that. I usually +use it to store the function to be executed when the menu option is +chosen (It's selected and may be the user pressed +<ENTER>);</p> +<div class="EXAMPLE"><a name="MMEUS" id="MMEUS"></a> +<p><b>Example 24. Menu User Pointer Usage</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <curses.h> +#include <menu.h> + +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) +#define CTRLD 4 + +char *choices[] = { + "Choice 1", + "Choice 2", + "Choice 3", + "Choice 4", + "Choice 5", + "Choice 6", + "Choice 7", + "Exit", + }; +void func(char *name); + +int main() +{ ITEM **my_items; + int c; + MENU *my_menu; + int n_choices, i; + ITEM *cur_item; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_GREEN, COLOR_BLACK); + init_pair(3, COLOR_MAGENTA, COLOR_BLACK); + + /* Initialize items */ + n_choices = ARRAY_SIZE(choices); + my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); + for(i = 0; i < n_choices; ++i) + { my_items[i] = new_item(choices[i], choices[i]); + /* Set the user pointer */ + set_item_userptr(my_items[i], func); + } + my_items[n_choices] = (ITEM *)NULL; + + /* Create menu */ + my_menu = new_menu((ITEM **)my_items); + + /* Post the menu */ + mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected"); + mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)"); + post_menu(my_menu); + refresh(); + + while((c = getch()) != KEY_F(1)) + { switch(c) + { case KEY_DOWN: + menu_driver(my_menu, REQ_DOWN_ITEM); + break; + case KEY_UP: + menu_driver(my_menu, REQ_UP_ITEM); + break; + case 10: /* Enter */ + { ITEM *cur; + void (*p)(char *); + + cur = current_item(my_menu); + p = item_userptr(cur); + p((char *)item_name(cur)); + pos_menu_cursor(my_menu); + break; + } + break; + } + } + unpost_menu(my_menu); + for(i = 0; i < n_choices; ++i) + free_item(my_items[i]); + free_menu(my_menu); + endwin(); +} + +void func(char *name) +{ move(20, 0); + clrtoeol(); + mvprintw(20, 0, "Item selected is : %s", name); +} </span></font> +</pre></td> +</tr> +</table> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms +Library</a></h2> +<p>Well. If you have seen those forms on web pages which take input +from users and do various kinds of things, you might be wondering +how would any one create such forms in text mode display. It's +quite difficult to write those nifty forms in plain ncurses. Forms +library tries to provide a basic frame work to build and maintain +forms with ease. It has lot of features(functions) which manage +validation, dynamic expansion of fields etc.. Let's see it in full +flow.</p> +<p>A form is a collection of fields; each field can be either a +label(static text) or a data-entry location. The forms also library +provides functions to divide forms into multiple pages.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="FORMBASICS" id="FORMBASICS">18.1. The +Basics</a></h3> +<p>Forms are created in much the same way as menus. First the +fields related to the form are created with new_field(). You can +set options for the fields, so that they can be displayed with some +fancy attributes, validated before the field looses focus etc.. +Then the fields are attached to form. After this, the form can be +posted to display and is ready to receive inputs. On the similar +lines to menu_driver(), the form is manipulated with form_driver(). +We can send requests to form_driver to move focus to a certain +field, move cursor to end of the field etc.. After the user enters +values in the fields and validation done, form can be unposted and +memory allocated can be freed.</p> +<p>The general flow of control of a forms program looks like +this.</p> +<ol type="1"> +<li> +<p>Initialize curses</p> +</li> +<li> +<p>Create fields using new_field(). You can specify the height and +width of the field, and its position on the form.</p> +</li> +<li> +<p>Create the forms with new_form() by specifying the fields to be +attached with.</p> +</li> +<li> +<p>Post the form with form_post() and refresh the screen.</p> +</li> +<li> +<p>Process the user requests with a loop and do necessary updates +to form with form_driver.</p> +</li> +<li> +<p>Unpost the menu with form_unpost()</p> +</li> +<li> +<p>Free the memory allocated to menu by free_form()</p> +</li> +<li> +<p>Free the memory allocated to the items with free_field()</p> +</li> +<li> +<p>End curses</p> +</li> +</ol> +<p>As you can see, working with forms library is much similar to +handling menu library. The following examples will explore various +aspects of form processing. Let's start the journey with a simple +example. first.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="COMPILEFORMS" id="COMPILEFORMS">18.2. +Compiling With the Forms Library</a></h3> +<p>To use forms library functions, you have to include form.h and +to link the program with forms library the flag -lform should be +added along with -lncurses in that order.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"> #include <form.h> + . + . + . + + compile and link: gcc <program file> -lform -lncurses</font> +</pre></td> +</tr> +</table> +<div class="EXAMPLE"><a name="FFOSI" id="FFOSI"></a> +<p><b>Example 25. Forms Basics</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <form.h> + +int main() +{ FIELD *field[3]; + FORM *my_form; + int ch; + + /* Initialize curses */ + initscr(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize the fields */ + field[0] = new_field(1, 10, 4, 18, 0, 0); + field[1] = new_field(1, 10, 6, 18, 0, 0); + field[2] = NULL; + + /* Set field options */ + set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */ + field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ + /* Field is filled up */ + set_field_back(field[1], A_UNDERLINE); + field_opts_off(field[1], O_AUTOSKIP); + + /* Create the form and post it */ + my_form = new_form(field); + post_form(my_form); + refresh(); + + mvprintw(4, 10, "Value 1:"); + mvprintw(6, 10, "Value 2:"); + refresh(); + + /* Loop through to get user requests */ + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case KEY_DOWN: + /* Go to next field */ + form_driver(my_form, REQ_NEXT_FIELD); + /* Go to the end of the present buffer */ + /* Leaves nicely at the last character */ + form_driver(my_form, REQ_END_LINE); + break; + case KEY_UP: + /* Go to previous field */ + form_driver(my_form, REQ_PREV_FIELD); + form_driver(my_form, REQ_END_LINE); + break; + default: + /* If this is a normal character, it gets */ + /* Printed */ + form_driver(my_form, ch); + break; + } + } + + /* Un post form and free the memory */ + unpost_form(my_form); + free_form(my_form); + free_field(field[0]); + free_field(field[1]); + + endwin(); + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>Above example is pretty straight forward. It creates two fields +with <var class="LITERAL">new_field()</var>. new_field() takes +height, width, starty, startx, number of offscreen rows and number +of additional working buffers. The fifth argument number of +offscreen rows specifies how much of the field to be shown. If it +is zero, the entire field is always displayed otherwise the form +will be scrollable when the user accesses not displayed parts of +the field. The forms library allocates one buffer per field to +store the data user enters. Using the last parameter to new_field() +we can specify it to allocate some additional buffers. These can be +used for any purpose you like.</p> +<p>After creating the fields, back ground attribute of both of them +is set to an underscore with set_field_back(). The AUTOSKIP option +is turned off using field_opts_off(). If this option is turned on, +focus will move to the next field in the form once the active field +is filled up completely.</p> +<p>After attaching the fields to the form, it is posted. Here on, +user inputs are processed in the while loop, by making +corresponding requests to form_driver. The details of all the +requests to the form_driver() are explained later.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PLAYFIELDS" id="PLAYFIELDS">18.3. +Playing with Fields</a></h3> +<p>Each form field is associated with a lot of attributes. They can +be manipulated to get the required effect and to have fun !!!. So +why wait?</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="FETCHINFO" id="FETCHINFO">18.3.1. +Fetching Size and Location of Field</a></h4> +<p>The parameters we have given at the time of creation of a field +can be retrieved with field_info(). It returns height, width, +starty, startx, number of offscreen rows, and number of additional +buffers into the parameters given to it. It is a sort of inverse of +new_field().</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int field_info( FIELD *field, /* field from which to fetch */ + int *height, *int width, /* field size */ + int *top, int *left, /* upper left corner */ + int *offscreen, /* number of offscreen rows */ + int *nbuf); /* number of working buffers */</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="MOVEFIELD" id="MOVEFIELD">18.3.2. Moving +the field</a></h4> +<p>The location of the field can be moved to a different position +with move_field().</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int move_field( FIELD *field, /* field to alter */ + int top, int left); /* new upper-left corner */</font> +</pre></td> +</tr> +</table> +<p>As usual, the changed position can be queried with +field_infor().</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="JUSTIFYFIELD" id="JUSTIFYFIELD">18.3.3. +Field Justification</a></h4> +<p>The justification to be done for the field can be fixed using +the function set_field_just().</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> int set_field_just(FIELD *field, /* field to alter */ + int justmode); /* mode to set */ + int field_just(FIELD *field); /* fetch justify mode of field */</font> +</pre></td> +</tr> +</table> +<p>The justification mode valued accepted and returned by these +functions are NO_JUSTIFICATION, JUSTIFY_RIGHT, JUSTIFY_LEFT, or +JUSTIFY_CENTER.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="FIELDDISPATTRIB" id= +"FIELDDISPATTRIB">18.3.4. Field Display Attributes</a></h4> +<p>As you have seen, in the above example, display attribute for +the fields can be set with set_field_fore() and setfield_back(). +These functions set foreground and background attribute of the +fields. You can also specify a pad character which will be filled +in the unfilled portion of the field. The pad character is set with +a call to set_field_pad(). Default pad value is a space. The +functions field_fore(), field_back, field_pad() can be used to +query the present foreground, background attributes and pad +character for the field. The following list gives the usage of +functions.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> int set_field_fore(FIELD *field, /* field to alter */ + chtype attr); /* attribute to set */ + +chtype field_fore(FIELD *field); /* field to query */ + /* returns foreground attribute */ + +int set_field_back(FIELD *field, /* field to alter */ + chtype attr); /* attribute to set */ + +chtype field_back(FIELD *field); /* field to query */ + /* returns background attribute */ + +int set_field_pad(FIELD *field, /* field to alter */ + int pad); /* pad character to set */ + +chtype field_pad(FIELD *field); /* field to query */ + /* returns present pad character */ </font> +</pre></td> +</tr> +</table> +<p>Though above functions seem quite simple, using colors with +set_field_fore() may be frustrating in the beginning. Let me first +explain about foreground and background attributes of a field. The +foreground attribute is associated with the character. That means a +character in the field is printed with the attribute you have set +with set_field_fore(). Background attribute is the attribute used +to fill background of field, whether any character is there or not. +So what about colors? Since colors are always defined in pairs, +what is the right way to display colored fields? Here's an example +clarifying color attributes.</p> +<div class="EXAMPLE"><a name="FFOAT" id="FFOAT"></a> +<p><b>Example 26. Form Attributes example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <form.h> + +int main() +{ FIELD *field[3]; + FORM *my_form; + int ch; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize few color pairs */ + init_pair(1, COLOR_WHITE, COLOR_BLUE); + init_pair(2, COLOR_WHITE, COLOR_BLUE); + + /* Initialize the fields */ + field[0] = new_field(1, 10, 4, 18, 0, 0); + field[1] = new_field(1, 10, 6, 18, 0, 0); + field[2] = NULL; + + /* Set field options */ + set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */ + set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */ + /* are printed in white */ + field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ + /* Field is filled up */ + set_field_back(field[1], A_UNDERLINE); + field_opts_off(field[1], O_AUTOSKIP); + + /* Create the form and post it */ + my_form = new_form(field); + post_form(my_form); + refresh(); + + set_current_field(my_form, field[0]); /* Set focus to the colored field */ + mvprintw(4, 10, "Value 1:"); + mvprintw(6, 10, "Value 2:"); + mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields"); + refresh(); + + /* Loop through to get user requests */ + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case KEY_DOWN: + /* Go to next field */ + form_driver(my_form, REQ_NEXT_FIELD); + /* Go to the end of the present buffer */ + /* Leaves nicely at the last character */ + form_driver(my_form, REQ_END_LINE); + break; + case KEY_UP: + /* Go to previous field */ + form_driver(my_form, REQ_PREV_FIELD); + form_driver(my_form, REQ_END_LINE); + break; + default: + /* If this is a normal character, it gets */ + /* Printed */ + form_driver(my_form, ch); + break; + } + } + + /* Un post form and free the memory */ + unpost_form(my_form); + free_form(my_form); + free_field(field[0]); + free_field(field[1]); + + endwin(); + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>Play with the color pairs and try to understand the foreground +and background attributes. In my programs using color attributes, I +usually set only the background with set_field_back(). Curses +simply doesn't allow defining individual color attributes.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="FIELDOPTIONBITS" id= +"FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4> +<p>There is also a large collection of field option bits you can +set to control various aspects of forms processing. You can +manipulate them with these functions:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_opts(FIELD *field, /* field to alter */ + int attr); /* attribute to set */ + +int field_opts_on(FIELD *field, /* field to alter */ + int attr); /* attributes to turn on */ + +int field_opts_off(FIELD *field, /* field to alter */ + int attr); /* attributes to turn off */ + +int field_opts(FIELD *field); /* field to query */ </font> +</pre></td> +</tr> +</table> +<p>The function set_field_opts() can be used to directly set +attributes of a field or you can choose to switch a few attributes +on and off with field_opts_on() and field_opts_off() selectively. +Anytime you can query the attributes of a field with field_opts(). +The following is the list of available options. By default, all +options are on.</p> +<div class="VARIABLELIST"> +<dl> +<dt>O_VISIBLE</dt> +<dd> +<p>Controls whether the field is visible on the screen. Can be used +during form processing to hide or pop up fields depending on the +value of parent fields.</p> +</dd> +<dt>O_ACTIVE</dt> +<dd> +<p>Controls whether the field is active during forms processing +(i.e. visited by form navigation keys). Can be used to make labels +or derived fields with buffer values alterable by the forms +application, not the user.</p> +</dd> +<dt>O_PUBLIC</dt> +<dd> +<p>Controls whether data is displayed during field entry. If this +option is turned off on a field, the library will accept and edit +data in that field, but it will not be displayed and the visible +field cursor will not move. You can turn off the O_PUBLIC bit to +define password fields.</p> +</dd> +<dt>O_EDIT</dt> +<dd> +<p>Controls whether the field's data can be modified. When this +option is off, all editing requests except <var class= +"LITERAL">REQ_PREV_CHOICE</var> and <var class= +"LITERAL">REQ_NEXT_CHOICE</var>will fail. Such read-only fields may +be useful for help messages.</p> +</dd> +<dt>O_WRAP</dt> +<dd> +<p>Controls word-wrapping in multi-line fields. Normally, when any +character of a (blank-separated) word reaches the end of the +current line, the entire word is wrapped to the next line (assuming +there is one). When this option is off, the word will be split +across the line break.</p> +</dd> +<dt>O_BLANK</dt> +<dd> +<p>Controls field blanking. When this option is on, entering a +character at the first field position erases the entire field +(except for the just-entered character).</p> +</dd> +<dt>O_AUTOSKIP</dt> +<dd> +<p>Controls automatic skip to next field when this one fills. +Normally, when the forms user tries to type more data into a field +than will fit, the editing location jumps to next field. When this +option is off, the user's cursor will hang at the end of the field. +This option is ignored in dynamic fields that have not reached +their size limit.</p> +</dd> +<dt>O_NULLOK</dt> +<dd> +<p>Controls whether validation is applied to blank fields. +Normally, it is not; the user can leave a field blank without +invoking the usual validation check on exit. If this option is off +on a field, exit from it will invoke a validation check.</p> +</dd> +<dt>O_PASSOK</dt> +<dd> +<p>Controls whether validation occurs on every exit, or only after +the field is modified. Normally the latter is true. Setting +O_PASSOK may be useful if your field's validation function may +change during forms processing.</p> +</dd> +<dt>O_STATIC</dt> +<dd> +<p>Controls whether the field is fixed to its initial dimensions. +If you turn this off, the field becomes dynamic and will stretch to +fit entered data.</p> +</dd> +</dl> +</div> +<p>A field's options cannot be changed while the field is currently +selected. However, options may be changed on posted fields that are +not current.</p> +<p>The option values are bit-masks and can be composed with +logical-or in the obvious way. You have seen the usage of switching +off O_AUTOSKIP option. The following example clarifies usage of +some more options. Other options are explained where +appropriate.</p> +<div class="EXAMPLE"><a name="FFOOP" id="FFOOP"></a> +<p><b>Example 27. Field Options Usage example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <form.h> + +#define STARTX 15 +#define STARTY 4 +#define WIDTH 25 + +#define N_FIELDS 3 + +int main() +{ FIELD *field[N_FIELDS]; + FORM *my_form; + int ch, i; + + /* Initialize curses */ + initscr(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize the fields */ + for(i = 0; i < N_FIELDS - 1; ++i) + field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0); + field[N_FIELDS - 1] = NULL; + + /* Set field options */ + set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */ + + field_opts_off(field[0], O_ACTIVE); /* This field is a static label */ + field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/ + field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */ + /* after last character is entered */ + + /* Create the form and post it */ + my_form = new_form(field); + post_form(my_form); + refresh(); + + set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */ + set_field_buffer(field[0], 0, "This is a static Field"); + /* Initialize the field */ + mvprintw(STARTY, STARTX - 10, "Field 1:"); + mvprintw(STARTY + 2, STARTX - 10, "Field 2:"); + refresh(); + + /* Loop through to get user requests */ + while((ch = getch()) != KEY_F(1)) + { switch(ch) + { case KEY_DOWN: + /* Go to next field */ + form_driver(my_form, REQ_NEXT_FIELD); + /* Go to the end of the present buffer */ + /* Leaves nicely at the last character */ + form_driver(my_form, REQ_END_LINE); + break; + case KEY_UP: + /* Go to previous field */ + form_driver(my_form, REQ_PREV_FIELD); + form_driver(my_form, REQ_END_LINE); + break; + default: + /* If this is a normal character, it gets */ + /* Printed */ + form_driver(my_form, ch); + break; + } + } + + /* Un post form and free the memory */ + unpost_form(my_form); + free_form(my_form); + free_field(field[0]); + free_field(field[1]); + + endwin(); + return 0; +}</span></font> +</pre></td> +</tr> +</table> +</div> +<p>This example, though useless, shows the usage of options. If +used properly, they can present information very effectively in a +form. The second field being not O_PUBLIC, does not show the +characters you are typing.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="FIELDSTATUS" id="FIELDSTATUS">18.3.6. +Field Status</a></h4> +<p>The field status specifies whether the field has got edited or +not. It is initially set to FALSE and when user enters something +and the data buffer gets modified it becomes TRUE. So a field's +status can be queried to find out whether it has been modified or +not. The following functions can assist in those operations.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_status(FIELD *field, /* field to alter */ + int status); /* status to set */ + +int field_status(FIELD *field); /* fetch status of field */</font> +</pre></td> +</tr> +</table> +<p>It's better to check the field's status only after after leaving +the field, as data buffer might not have been updated yet as the +validation is still due. To guarantee that right status is +returned, call field_status() either (1) in the field's exit +validation check routine, (2) from the field's or form's +initialization or termination hooks, or (3) just after a +REQ_VALIDATION request has been processed by the forms driver</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="FIELDUSERPTR" id="FIELDUSERPTR">18.3.7. +Field User Pointer</a></h4> +<p>Every field structure contains one pointer that can be used by +the user for various purposes. It is not touched by forms library +and can be used for any purpose by the user. The following +functions set and fetch user pointer.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000">int set_field_userptr(FIELD *field, + char *userptr); /* the user pointer you wish to associate */ + /* with the field */ + +char *field_userptr(FIELD *field); /* fetch user pointer of the field */</font> +</pre></td> +</tr> +</table> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id= +"VARIABLESIZEFIELDS">18.3.8. Variable-Sized Fields</a></h4> +<p>If you want a dynamically changing field with variable width, +this is the feature you want to put to full use. This will allow +the user to enter more data than the original size of the field and +let the field grow. According to the field orientation it will +scroll horizontally or vertically to incorporate the new data.</p> +<p>To make a field dynamically growable, the option O_STATIC should +be turned off. This can be done with a</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"> field_opts_off(field_pointer, O_STATIC);</font> +</pre></td> +</tr> +</table> +<p>But it's usually not advisable to allow a field to grow +infinitely. You can set a maximum limit to the growth of the field +with</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_max_field(FIELD *field, /* Field on which to operate */ + int max_growth); /* maximum growth allowed for the field */</font> +</pre></td> +</tr> +</table> +<p>The field info for a dynamically growable field can be retrieved +by</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int dynamic_field_info( FIELD *field, /* Field on which to operate */ + int *prows, /* number of rows will be filled in this */ + int *pcols, /* number of columns will be filled in this*/ + int *pmax) /* maximum allowable growth will be filled */ + /* in this */</font> +</pre></td> +</tr> +</table> +Though field_info work as usual, it is advisable to use this +function to get the proper attributes of a dynamically growable +field. +<p>Recall the library routine new_field; a new field created with +height set to one will be defined to be a one line field. A new +field created with height greater than one will be defined to be a +multi line field.</p> +<p>A one line field with O_STATIC turned off (dynamically growable +field) will contain a single fixed row, but the number of columns +can increase if the user enters more data than the initial field +will hold. The number of columns displayed will remain fixed and +the additional data will scroll horizontally.</p> +<p>A multi line field with O_STATIC turned off (dynamically +growable field) will contain a fixed number of columns, but the +number of rows can increase if the user enters more data than the +initial field will hold. The number of rows displayed will remain +fixed and the additional data will scroll vertically.</p> +<p>The above two paragraphs pretty much describe a dynamically +growable field's behavior. The way other parts of forms library +behaves is described below:</p> +<ol type="1"> +<li> +<p>The field option O_AUTOSKIP will be ignored if the option +O_STATIC is off and there is no maximum growth specified for the +field. Currently, O_AUTOSKIP generates an automatic REQ_NEXT_FIELD +form driver request when the user types in the last character +position of a field. On a growable field with no maximum growth +specified, there is no last character position. If a maximum growth +is specified, the O_AUTOSKIP option will work as normal if the +field has grown to its maximum size.</p> +</li> +<li> +<p>The field justification will be ignored if the option O_STATIC +is off. Currently, set_field_just can be used to JUSTIFY_LEFT, +JUSTIFY_RIGHT, JUSTIFY_CENTER the contents of a one line field. A +growable one line field will, by definition, grow and scroll +horizontally and may contain more data than can be justified. The +return from field_just will be unchanged.</p> +</li> +<li> +<p>The overloaded form driver request REQ_NEW_LINE will operate the +same way regardless of the O_NL_OVERLOAD form option if the field +option O_STATIC is off and there is no maximum growth specified for +the field. Currently, if the form option O_NL_OVERLOAD is on, +REQ_NEW_LINE implicitly generates a REQ_NEXT_FIELD if called from +the last line of a field. If a field can grow without bound, there +is no last line, so REQ_NEW_LINE will never implicitly generate a +REQ_NEXT_FIELD. If a maximum growth limit is specified and the +O_NL_OVERLOAD form option is on, REQ_NEW_LINE will only implicitly +generate REQ_NEXT_FIELD if the field has grown to its maximum size +and the user is on the last line.</p> +</li> +<li> +<p>The library call dup_field will work as usual; it will duplicate +the field, including the current buffer size and contents of the +field being duplicated. Any specified maximum growth will also be +duplicated.</p> +</li> +<li> +<p>The library call link_field will work as usual; it will +duplicate all field attributes and share buffers with the field +being linked. If the O_STATIC field option is subsequently changed +by a field sharing buffers, how the system reacts to an attempt to +enter more data into the field than the buffer will currently hold +will depend on the setting of the option in the current field.</p> +</li> +<li> +<p>The library call field_info will work as usual; the variable +nrow will contain the value of the original call to new_field. The +user should use dynamic_field_info, described above, to query the +current size of the buffer.</p> +</li> +</ol> +<p>Some of the above points make sense only after explaining form +driver. We will be looking into that in next few sections.</p> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="FORMWINDOWS" id="FORMWINDOWS">18.4. Form +Windows</a></h3> +<p>The form windows concept is pretty much similar to menu windows. +Every form is associated with a main window and a sub window. The +form main window displays any title or border associated or +whatever the user wishes. Then the sub window contains all the +fields and displays them according to their position. This gives +the flexibility of manipulating fancy form displaying very +easily.</p> +<p>Since this is pretty much similar to menu windows, I am +providing an example with out much explanation. The functions are +similar and they work the same way.</p> +<div class="EXAMPLE"><a name="FFOWI" id="FFOWI"></a> +<p><b>Example 28. Form Windows Example</b></p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000"><span class= +"INLINEMEDIAOBJECT">#include <form.h> + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); + +int main() +{ + FIELD *field[3]; + FORM *my_form; + WINDOW *my_form_win; + int ch, rows, cols; + + /* Initialize curses */ + initscr(); + start_color(); + cbreak(); + noecho(); + keypad(stdscr, TRUE); + + /* Initialize few color pairs */ + init_pair(1, COLOR_RED, COLOR_BLACK); + + /* Initialize the fields */ + field[0] = new_field(1, 10, 6, 1, 0, 0); + field[1] = new_field(1, 10, 8, 1, 0, 0); + field[2] = NULL; + + /* Set field options */ + set_field_back(field[0], A_UNDERLINE); + field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ + /* Field is filled up */ + set_field_back(field[1], A_UNDERLINE); + field_opts_off(field[1], O_AUTOSKIP); + + /* Create the form and post it */ + my_form = new_form(field); + + /* Calculate the area required for the form */ + scale_form(my_form, &rows, &cols); + + /* Create the window to be associated with the form */ + my_form_win = newwin(rows + 4, cols + 4, 4, 4); + keypad(my_form_win, TRUE); + + /* Set main window and sub window */ + set_form_win(my_form, my_form_win); + set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2)); + + /* Print a border around the main window and print a title */ + box(my_form_win, 0, 0); + print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1)); + + post_form(my_form); + wrefresh(my_form_win); + + mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields"); + refresh(); + + /* Loop through to get user requests */ + while((ch = wgetch(my_form_win)) != KEY_F(1)) + { switch(ch) + { case KEY_DOWN: + /* Go to next field */ + form_driver(my_form, REQ_NEXT_FIELD); + /* Go to the end of the present buffer */ + /* Leaves nicely at the last character */ + form_driver(my_form, REQ_END_LINE); + break; + case KEY_UP: + /* Go to previous field */ + form_driver(my_form, REQ_PREV_FIELD); + form_driver(my_form, REQ_END_LINE); + break; + default: + /* If this is a normal character, it gets */ + /* Printed */ + form_driver(my_form, ch); + break; + } + } + + /* Un post form and free the memory */ + unpost_form(my_form); + free_form(my_form); + free_field(field[0]); + free_field(field[1]); + + endwin(); + return 0; +} + +void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) +{ int length, x, y; + float temp; + + if(win == NULL) + win = stdscr; + getyx(win, y, x); + if(startx != 0) + x = startx; + if(starty != 0) + y = starty; + if(width == 0) + width = 80; + + length = strlen(string); + temp = (width - length)/ 2; + x = startx + (int)temp; + wattron(win, color); + mvwprintw(win, y, x, "%s", string); + wattroff(win, color); + refresh(); +}</span></font> +</pre></td> +</tr> +</table> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="FILEDVALIDATE" id="FILEDVALIDATE">18.5. +Field Validation</a></h3> +<p>By default, a field will accept any data input by the user. It +is possible to attach validation to the field. Then any attempt by +the user to leave the field, while it contains data that doesn't +match the validation type will fail. Some validation types also +have a character-validity check for each time a character is +entered in the field.</p> +<p>Validation can be attached to a field with the following +function.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + FIELDTYPE *ftype, /* type to associate */ + ...); /* additional arguments*/</font> +</pre></td> +</tr> +</table> +Once set, the validation type for a field can be queried with +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">FIELDTYPE *field_type(FIELD *field); /* field to query */</font> +</pre></td> +</tr> +</table> +<p>The form driver validates the data in a field only when data is +entered by the end-user. Validation does not occur when</p> +<ul> +<li> +<p>the application program changes the field value by calling +set_field_buffer.</p> +</li> +<li> +<p>linked field values are changed indirectly -- by changing the +field to which they are linked</p> +</li> +</ul> +<p>The following are the pre-defined validation types. You can also +specify custom validation, though it's a bit tricky and +cumbersome.</p> +<h1 class="BRIDGEHEAD"><a name="AEN1069" id= +"AEN1069"></a>TYPE_ALPHA</h1> +<p>This field type accepts alphabetic data; no blanks, no digits, +no special characters (this is checked at character-entry time). It +is set up with:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + TYPE_ALPHA, /* type to associate */ + int width); /* maximum width of field */</font> +</pre></td> +</tr> +</table> +<p>The width argument sets a minimum width of data. The user has to +enter at-least width number of characters before he can leave the +field. Typically you'll want to set this to the field width; if +it's greater than the field width, the validation check will always +fail. A minimum width of zero makes field completion optional.</p> +<h1 class="BRIDGEHEAD"><a name="AEN1073" id= +"AEN1073"></a>TYPE_ALNUM</h1> +<p>This field type accepts alphabetic data and digits; no blanks, +no special characters (this is checked at character-entry time). It +is set up with:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + TYPE_ALNUM, /* type to associate */ + int width); /* maximum width of field */</font> +</pre></td> +</tr> +</table> +<p>The width argument sets a minimum width of data. As with +TYPE_ALPHA, typically you'll want to set this to the field width; +if it's greater than the field width, the validation check will +always fail. A minimum width of zero makes field completion +optional.</p> +<h1 class="BRIDGEHEAD"><a name="AEN1077" id= +"AEN1077"></a>TYPE_ENUM</h1> +<p>This type allows you to restrict a field's values to be among a +specified set of string values (for example, the two-letter postal +codes for U.S. states). It is set up with:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + TYPE_ENUM, /* type to associate */ + char **valuelist; /* list of possible values */ + int checkcase; /* case-sensitive? */ + int checkunique); /* must specify uniquely? */</font> +</pre></td> +</tr> +</table> +<p>The valuelist parameter must point at a NULL-terminated list of +valid strings. The checkcase argument, if true, makes comparison +with the string case-sensitive.</p> +<p>When the user exits a TYPE_ENUM field, the validation procedure +tries to complete the data in the buffer to a valid entry. If a +complete choice string has been entered, it is of course valid. But +it is also possible to enter a prefix of a valid string and have it +completed for you.</p> +<p>By default, if you enter such a prefix and it matches more than +one value in the string list, the prefix will be completed to the +first matching value. But the checkunique argument, if true, +requires prefix matches to be unique in order to be valid.</p> +<p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests can be +particularly useful with these fields.</p> +<h1 class="BRIDGEHEAD"><a name="AEN1084" id= +"AEN1084"></a>TYPE_INTEGER</h1> +<p>This field type accepts an integer. It is set up as follows:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + TYPE_INTEGER, /* type to associate */ + int padding, /* # places to zero-pad to */ + int vmin, int vmax); /* valid range */</font> +</pre></td> +</tr> +</table> +<p>Valid characters consist of an optional leading minus and +digits. The range check is performed on exit. If the range maximum +is less than or equal to the minimum, the range is ignored.</p> +<p>If the value passes its range check, it is padded with as many +leading zero digits as necessary to meet the padding argument.</p> +<p>A TYPE_INTEGER value buffer can conveniently be interpreted with +the C library function atoi(3).</p> +<h1 class="BRIDGEHEAD"><a name="AEN1090" id= +"AEN1090"></a>TYPE_NUMERIC</h1> +<p>This field type accepts a decimal number. It is set up as +follows:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + TYPE_NUMERIC, /* type to associate */ + int padding, /* # places of precision */ + int vmin, int vmax); /* valid range */</font> +</pre></td> +</tr> +</table> +<p>Valid characters consist of an optional leading minus and +digits. possibly including a decimal point. The range check is +performed on exit. If the range maximum is less than or equal to +the minimum, the range is ignored.</p> +<p>If the value passes its range check, it is padded with as many +trailing zero digits as necessary to meet the padding argument.</p> +<p>A TYPE_NUMERIC value buffer can conveniently be interpreted with +the C library function atof(3).</p> +<h1 class="BRIDGEHEAD"><a name="AEN1096" id= +"AEN1096"></a>TYPE_REGEXP</h1> +<p>This field type accepts data matching a regular expression. It +is set up as follows:</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_field_type(FIELD *field, /* field to alter */ + TYPE_REGEXP, /* type to associate */ + char *regexp); /* expression to match */</font> +</pre></td> +</tr> +</table> +<p>The syntax for regular expressions is that of regcomp(3). The +check for regular-expression match is performed on exit.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="FORMDRIVER" id="FORMDRIVER">18.6. Form +Driver: The work horse of the forms system</a></h3> +<p>As in the menu system, form_driver() plays a very important role +in forms system. All types of requests to forms system should be +funneled through form_driver().</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int form_driver(FORM *form, /* form on which to operate */ + int request) /* form request code */</font> +</pre></td> +</tr> +</table> +<p>As you have seen some of the examples above, you have to be in a +loop looking for user input and then decide whether it's a field +data or a form request. The form requests are then passed to +form_driver() to do the work.</p> +<p>The requests roughly can be divided into following categories. +Different requests and their usage is explained below:</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="PAGENAVREQ" id="PAGENAVREQ">18.6.1. Page +Navigation Requests</a></h4> +<p>These requests cause page-level moves through the form, +triggering display of a new form screen. A form can be made of +multiple pages. If you have a big form with lot of fields and +logical sections, then you can divide the form into pages. The +function set_new_page() to set a new page at the field +specified.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">int set_new_page(FIELD *field,/* Field at which page break to be set or unset */ + bool new_page_flag); /* should be TRUE to put a break */</font> +</pre></td> +</tr> +</table> +<p>The following requests allow you to move to different pages</p> +<ul> +<li> +<p><em>REQ_NEXT_PAGE</em> Move to the next form page.</p> +</li> +<li> +<p><em>REQ_PREV_PAGE</em> Move to the previous form page.</p> +</li> +<li> +<p><em>REQ_FIRST_PAGE</em> Move to the first form page.</p> +</li> +<li> +<p><em>REQ_LAST_PAGE</em> Move to the last form page.</p> +</li> +</ul> +<p>These requests treat the list as cyclic; that is, REQ_NEXT_PAGE +from the last page goes to the first, and REQ_PREV_PAGE from the +first page goes to the last.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="INTERFIELDNAVREQ" id= +"INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation Requests</a></h4> +<p>These requests handle navigation between fields on the same +page.</p> +<ul> +<li> +<p><em>REQ_NEXT_FIELD</em> Move to next field.</p> +</li> +<li> +<p><em>REQ_PREV_FIELD</em> Move to previous field.</p> +</li> +<li> +<p><em>REQ_FIRST_FIELD</em> Move to the first field.</p> +</li> +<li> +<p><em>REQ_LAST_FIELD</em> Move to the last field.</p> +</li> +<li> +<p><em>REQ_SNEXT_FIELD</em> Move to sorted next field.</p> +</li> +<li> +<p><em>REQ_SPREV_FIELD</em> Move to sorted previous field.</p> +</li> +<li> +<p><em>REQ_SFIRST_FIELD</em> Move to the sorted first field.</p> +</li> +<li> +<p><em>REQ_SLAST_FIELD</em> Move to the sorted last field.</p> +</li> +<li> +<p><em>REQ_LEFT_FIELD</em> Move left to field.</p> +</li> +<li> +<p><em>REQ_RIGHT_FIELD</em> Move right to field.</p> +</li> +<li> +<p><em>REQ_UP_FIELD</em> Move up to field.</p> +</li> +<li> +<p><em>REQ_DOWN_FIELD</em> Move down to field.</p> +</li> +</ul> +<p>These requests treat the list of fields on a page as cyclic; +that is, REQ_NEXT_FIELD from the last field goes to the first, and +REQ_PREV_FIELD from the first field goes to the last. The order of +the fields for these (and the REQ_FIRST_FIELD and REQ_LAST_FIELD +requests) is simply the order of the field pointers in the form +array (as set up by new_form() or set_form_fields()</p> +<p>It is also possible to traverse the fields as if they had been +sorted in screen-position order, so the sequence goes left-to-right +and top-to-bottom. To do this, use the second group of four +sorted-movement requests.</p> +<p>Finally, it is possible to move between fields using visual +directions up, down, right, and left. To accomplish this, use the +third group of four requests. Note, however, that the position of a +form for purposes of these requests is its upper-left corner.</p> +<p>For example, suppose you have a multi-line field B, and two +single-line fields A and C on the same line with B, with A to the +left of B and C to the right of B. A REQ_MOVE_RIGHT from A will go +to B only if A, B, and C all share the same first line; otherwise +it will skip over B to C.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id= +"INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation Requests</a></h4> +<p>These requests drive movement of the edit cursor within the +currently selected field.</p> +<ul> +<li> +<p><em>REQ_NEXT_CHAR</em> Move to next character.</p> +</li> +<li> +<p><em>REQ_PREV_CHAR</em> Move to previous character.</p> +</li> +<li> +<p><em>REQ_NEXT_LINE</em> Move to next line.</p> +</li> +<li> +<p><em>REQ_PREV_LINE</em> Move to previous line.</p> +</li> +<li> +<p><em>REQ_NEXT_WORD</em> Move to next word.</p> +</li> +<li> +<p><em>REQ_PREV_WORD</em> Move to previous word.</p> +</li> +<li> +<p><em>REQ_BEG_FIELD</em> Move to beginning of field.</p> +</li> +<li> +<p><em>REQ_END_FIELD</em> Move to end of field.</p> +</li> +<li> +<p><em>REQ_BEG_LINE</em> Move to beginning of line.</p> +</li> +<li> +<p><em>REQ_END_LINE</em> Move to end of line.</p> +</li> +<li> +<p><em>REQ_LEFT_CHAR</em> Move left in field.</p> +</li> +<li> +<p><em>REQ_RIGHT_CHAR</em> Move right in field.</p> +</li> +<li> +<p><em>REQ_UP_CHAR</em> Move up in field.</p> +</li> +<li> +<p><em>REQ_DOWN_CHAR</em> Move down in field.</p> +</li> +</ul> +<p>Each word is separated from the previous and next characters by +whitespace. The commands to move to beginning and end of line or +field look for the first or last non-pad character in their +ranges.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="SCROLLREQ" id="SCROLLREQ">18.6.4. +Scrolling Requests</a></h4> +<p>Fields that are dynamic and have grown and fields explicitly +created with offscreen rows are scrollable. One-line fields scroll +horizontally; multi-line fields scroll vertically. Most scrolling +is triggered by editing and intra-field movement (the library +scrolls the field to keep the cursor visible). It is possible to +explicitly request scrolling with the following requests:</p> +<ul> +<li> +<p><em>REQ_SCR_FLINE</em> Scroll vertically forward a line.</p> +</li> +<li> +<p><em>REQ_SCR_BLINE</em> Scroll vertically backward a line.</p> +</li> +<li> +<p><em>REQ_SCR_FPAGE</em> Scroll vertically forward a page.</p> +</li> +<li> +<p><em>REQ_SCR_BPAGE</em> Scroll vertically backward a page.</p> +</li> +<li> +<p><em>REQ_SCR_FHPAGE</em> Scroll vertically forward half a +page.</p> +</li> +<li> +<p><em>REQ_SCR_BHPAGE</em> Scroll vertically backward half a +page.</p> +</li> +<li> +<p><em>REQ_SCR_FCHAR</em> Scroll horizontally forward a +character.</p> +</li> +<li> +<p><em>REQ_SCR_BCHAR</em> Scroll horizontally backward a +character.</p> +</li> +<li> +<p><em>REQ_SCR_HFLINE</em> Scroll horizontally one field width +forward.</p> +</li> +<li> +<p><em>REQ_SCR_HBLINE</em> Scroll horizontally one field width +backward.</p> +</li> +<li> +<p><em>REQ_SCR_HFHALF</em> Scroll horizontally one half field width +forward.</p> +</li> +<li> +<p><em>REQ_SCR_HBHALF</em> Scroll horizontally one half field width +backward.</p> +</li> +</ul> +<p>For scrolling purposes, a page of a field is the height of its +visible part.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5. Editing +Requests</a></h4> +<p>When you pass the forms driver an ASCII character, it is treated +as a request to add the character to the field's data buffer. +Whether this is an insertion or a replacement depends on the +field's edit mode (insertion is the default.</p> +<p>The following requests support editing the field and changing +the edit mode:</p> +<ul> +<li> +<p><em>REQ_INS_MODE</em> Set insertion mode.</p> +</li> +<li> +<p><em>REQ_OVL_MODE</em> Set overlay mode.</p> +</li> +<li> +<p><em>REQ_NEW_LINE</em> New line request (see below for +explanation).</p> +</li> +<li> +<p><em>REQ_INS_CHAR</em> Insert space at character location.</p> +</li> +<li> +<p><em>REQ_INS_LINE</em> Insert blank line at character +location.</p> +</li> +<li> +<p><em>REQ_DEL_CHAR</em> Delete character at cursor.</p> +</li> +<li> +<p><em>REQ_DEL_PREV</em> Delete previous word at cursor.</p> +</li> +<li> +<p><em>REQ_DEL_LINE</em> Delete line at cursor.</p> +</li> +<li> +<p><em>REQ_DEL_WORD</em> Delete word at cursor.</p> +</li> +<li> +<p><em>REQ_CLR_EOL</em> Clear to end of line.</p> +</li> +<li> +<p><em>REQ_CLR_EOF</em> Clear to end of field.</p> +</li> +<li> +<p><em>REQ_CLR_FIELD</em> Clear entire field.</p> +</li> +</ul> +<p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV requests is +complicated and partly controlled by a pair of forms options. The +special cases are triggered when the cursor is at the beginning of +a field, or on the last line of the field.</p> +<p>First, we consider REQ_NEW_LINE:</p> +<p>The normal behavior of REQ_NEW_LINE in insert mode is to break +the current line at the position of the edit cursor, inserting the +portion of the current line after the cursor as a new line +following the current and moving the cursor to the beginning of +that new line (you may think of this as inserting a newline in the +field buffer).</p> +<p>The normal behavior of REQ_NEW_LINE in overlay mode is to clear +the current line from the position of the edit cursor to end of +line. The cursor is then moved to the beginning of the next +line.</p> +<p>However, REQ_NEW_LINE at the beginning of a field, or on the +last line of a field, instead does a REQ_NEXT_FIELD. O_NL_OVERLOAD +option is off, this special action is disabled.</p> +<p>Now, let us consider REQ_DEL_PREV:</p> +<p>The normal behavior of REQ_DEL_PREV is to delete the previous +character. If insert mode is on, and the cursor is at the start of +a line, and the text on that line will fit on the previous one, it +instead appends the contents of the current line to the previous +one and deletes the current line (you may think of this as deleting +a newline from the field buffer).</p> +<p>However, REQ_DEL_PREV at the beginning of a field is instead +treated as a REQ_PREV_FIELD.</p> +<p>If the O_BS_OVERLOAD option is off, this special action is +disabled and the forms driver just returns E_REQUEST_DENIED.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="ORDERREQ" id="ORDERREQ">18.6.6. Order +Requests</a></h4> +<p>If the type of your field is ordered, and has associated +functions for getting the next and previous values of the type from +a given value, there are requests that can fetch that value into +the field buffer:</p> +<ul> +<li> +<p><em>REQ_NEXT_CHOICE</em> Place the successor value of the +current value in the buffer.</p> +</li> +<li> +<p><em>REQ_PREV_CHOICE</em> Place the predecessor value of the +current value in the buffer.</p> +</li> +</ul> +<p>Of the built-in field types, only TYPE_ENUM has built-in +successor and predecessor functions. When you define a field type +of your own (see Custom Validation Types), you can associate our +own ordering functions.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="APPLICCOMMANDS" id= +"APPLICCOMMANDS">18.6.7. Application Commands</a></h4> +<p>Form requests are represented as integers above the curses value +greater than KEY_MAX and less than or equal to the constant +MAX_COMMAND. A value within this range gets ignored by +form_driver(). So this can be used for any purpose by the +application. It can be treated as an application specific action +and take corresponding action.</p> +</div> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and Widget +Libraries</a></h2> +<p>Now that you have seen the capabilities of ncurses and its +sister libraries, you are rolling your sleeves up and gearing for a +project that heavily manipulates screen. But wait.. It can be +pretty difficult to write and maintain complex GUI widgets in plain +ncurses or even with the additional libraries. There are some +ready-to-use tools and widget libraries that can be used instead of +writing your own widgets. You can use some of them, get ideas from +the code, or even extend them.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses +Development Kit)</a></h3> +<p>In the author's words</p> +<p><em>CDK stands for 'Curses Development Kit' and it currently +contains 21 ready to use widgets which facilitate the speedy +development of full screen curses programs.</em></p> +<p>The kit provides some useful widgets, which can be used in your +programs directly. It's pretty well written and the documentation +is very good. The examples in the examples directory can be a good +place to start for beginners. The CDK can be downloaded from +<a href="http://invisible-island.net/cdk/" target= +"_top">http://invisible-island.net/cdk/</a> . Follow the +instructions in README file to install it.</p> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="WIDGETLIST" id="WIDGETLIST">19.1.1. +Widget List</a></h4> +<p>The following is the list of widgets provided with cdk and their +description.</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color="#000000">Widget Type Quick Description +=========================================================================== +Alphalist Allows a user to select from a list of words, with + the ability to narrow the search list by typing in a + few characters of the desired word. +Buttonbox This creates a multiple button widget. +Calendar Creates a little simple calendar widget. +Dialog Prompts the user with a message, and the user + can pick an answer from the buttons provided. +Entry Allows the user to enter various types of information. +File Selector A file selector built from Cdk base widgets. This + example shows how to create more complicated widgets + using the Cdk widget library. +Graph Draws a graph. +Histogram Draws a histogram. +Item List Creates a pop up field which allows the user to select + one of several choices in a small field. Very useful + for things like days of the week or month names. +Label Displays messages in a pop up box, or the label can be + considered part of the screen. +Marquee Displays a message in a scrolling marquee. +Matrix Creates a complex matrix with lots of options. +Menu Creates a pull-down menu interface. +Multiple Line Entry A multiple line entry field. Very useful + for long fields. (like a description + field) +Radio List Creates a radio button list. +Scale Creates a numeric scale. Used for allowing a user to + pick a numeric value and restrict them to a range of + values. +Scrolling List Creates a scrolling list/menu list. +Scrolling Window Creates a scrolling log file viewer. Can add + information into the window while its running. + A good widget for displaying the progress of + something. (akin to a console window) +Selection List Creates a multiple option selection list. +Slider Akin to the scale widget, this widget provides a + visual slide bar to represent the numeric value. +Template Creates a entry field with character sensitive + positions. Used for pre-formatted fields like + dates and phone numbers. +Viewer This is a file/information viewer. Very useful + when you need to display loads of information. +===========================================================================</font> +</pre></td> +</tr> +</table> +<p>A few of the widgets are modified by Thomas Dickey in recent +versions.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="CDKATTRACT" id="CDKATTRACT">19.1.2. Some +Attractive Features</a></h4> +<p>Apart from making our life easier with readily usable widgets, +cdk solves one frustrating problem with printing multi colored +strings, justified strings elegantly. Special formatting tags can +be embedded in the strings which are passed to CDK functions. For +Example</p> +<p>If the string</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000">"</B/1>This line should have a yellow foreground and a blue +background.<!1>"</font> +</pre></td> +</tr> +</table> +<p>given as a parameter to newCDKLabel(), it prints the line with +yellow foreground and blue background. There are other tags +available for justifying string, embedding special drawing +characters etc.. Please refer to the man page cdk_display(3X) for +details. The man page explains the usage with nice examples.</p> +</div> +<div class="SECT3"> +<hr> +<h4 class="SECT3"><a name="CDKCONCLUSION" id= +"CDKCONCLUSION">19.1.3. Conclusion</a></h4> +<p>All in all, CDK is a well-written package of widgets, which if +used properly can form a strong frame work for developing complex +GUI.</p> +</div> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The +dialog</a></h3> +<p>Long long ago, in September 1994, when few people knew linux, +Jeff Tranter wrote an <a href= +"http://www2.linuxjournal.com/lj-issues/issue5/2807.html" target= +"_top">article</a> on dialog in Linux Journal. He starts the +article with these words..</p> +<p><em>Linux is based on the Unix operating system, but also +features a number of unique and useful kernel features and +application programs that often go beyond what is available under +Unix. One little-known gem is "dialog", a utility for creating +professional-looking dialog boxes from within shell scripts. This +article presents a tutorial introduction to the dialog utility, and +shows examples of how and where it can be used</em></p> +<p>As he explains, dialog is a real gem in making +professional-looking dialog boxes with ease. It creates a variety +of dialog boxes, menus, check lists etc.. It is usually installed +by default. If not, you can download it from <a href= +"http://invisible-island.net/dialog/" target="_top">Thomas +Dickey</a>'s site.</p> +<p>The above-mentioned article gives a very good overview of its +uses and capabilites. The man page has more details. It can be used +in variety of situations. One good example is building of linux +kernel in text mode. Linux kernel uses a modified version of dialog +tailored for its needs.</p> +<p>dialog was initially designed to be used with shell scripts. If +you want to use its functionality in a c program, then you can use +libdialog. The documentation regarding this is sparse. Definitive +reference is the dialog.h header file which comes with the library. +You may need to hack here and there to get the required output. The +source is easily customizable. I have used it on a number of +occasions by modifying the code.</p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="PERLCURSES" id="PERLCURSES">19.3. Perl +Curses Modules CURSES::FORM and CURSES::WIDGETS</a></h3> +<p>The perl module Curses, Curses::Form and Curses::Widgets give +access to curses from perl. If you have curses and basic perl is +installed, you can get these modules from <a href= +"http://www.cpan.org/modules/01modules.index.html" target= +"_top">CPAN All Modules page</a>. Get the three zipped modules in +the Curses category. Once installed you can use these modules from +perl scripts like any other module. For more information on perl +modules see perlmod man page. The above modules come with good +documentation and they have some demo scripts to test the +functionality. Though the widgets provided are very rudimentary, +these modules provide good access to curses library from perl.</p> +<p>Some of my code examples are converted to perl by Anuradha +Ratnaweera and they are available in the <var class= +"LITERAL">perl</var> directory.</p> +<p>For more information see man pages Curses(3) , Curses::Form(3) +and Curses::Widgets(3). These pages are installed only when the +above modules are acquired and installed.</p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20. Just For +Fun !!!</a></h2> +<p>This section contains few programs written by me just for fun. +They don't signify a better programming practice or the best way of +using ncurses. They are provided here so as to allow beginners to +get ideas and add more programs to this section. If you have +written a couple of nice, simple programs in curses and want them +to included here, contact <a href="mailto:ppadala@gmail.com" +target="_top">me</a>.</p> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="GAMEOFLIFE" id="GAMEOFLIFE">20.1. The +Game of Life</a></h3> +<p>Game of life is a wonder of math. In <a href= +"http://www.math.com/students/wonders/life/life.html" target= +"_top">Paul Callahan</a>'s words</p> +<table border="0" bgcolor="#E0E0E0" width="100%"> +<tr> +<td> +<pre class="PROGRAMLISTING"> +<font color= +"#000000"><em>The Game of Life (or simply Life) is not a game in the conventional sense. There +are no players, and no winning or losing. Once the "pieces" are placed in the +starting position, the rules determine everything that happens later. +Nevertheless, Life is full of surprises! In most cases, it is impossible to look +at a starting position (or pattern) and see what will happen in the future. The +only way to find out is to follow the rules of the game.</em></font> +</pre></td> +</tr> +</table> +<p>This program starts with a simple inverted U pattern and shows +how wonderful life works. There is a lot of room for improvement in +the program. You can let the user enter pattern of his choice or +even take input from a file. You can also change rules and play +with a lot of variations. Search on <a href="http://www.google.com" +target="_top">google</a> for interesting information on game of +life.</p> +<p><em>File Path: JustForFun/life.c</em></p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic +Square</a></h3> +<p>Magic Square, another wonder of math, is very simple to +understand but very difficult to make. In a magic square sum of the +numbers in each row, each column is equal. Even diagnol sum can be +equal. There are many variations which have special properties.</p> +<p>This program creates a simple magic square of odd order.</p> +<p><em>File Path: JustForFun/magic.c</em></p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers of +Hanoi</a></h3> +<p>The famous towers of hanoi solver. The aim of the game is to +move the disks on the first peg to last peg, using middle peg as a +temporary stay. The catch is not to place a larger disk over a +small disk at any time.</p> +<p><em>File Path: JustForFun/hanoi.c</em></p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens +Puzzle</a></h3> +<p>The objective of the famous N-Queen puzzle is to put N queens on +a N X N chess board without attacking each other.</p> +<p>This program solves it with a simple backtracking technique.</p> +<p><em>File Path: JustForFun/queens.c</em></p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5. +Shuffle</a></h3> +<p>A fun game, if you have time to kill.</p> +<p><em>File Path: JustForFun/shuffle.c</em></p> +</div> +<div class="SECT2"> +<hr> +<h3 class="SECT2"><a name="TT" id="TT">20.6. Typing Tutor</a></h3> +<p>A simple typing tutor, I created more out of need than for ease +of use. If you know how to put your fingers correctly on the +keyboard, but lack practice, this can be helpful.</p> +<p><em>File Path: JustForFun/tt.c</em></p> +</div> +</div> +<div class="SECT1"> +<hr> +<h2 class="SECT1"><a name="REF" id="REF">21. References</a></h2> +<ul> +<li> +<p>NCURSES man pages</p> +</li> +<li> +<p>NCURSES FAQ at <a href= +"http://invisible-island.net/ncurses/ncurses.faq.html" target= +"_top">http://invisible-island.net/ncurses/ncurses.faq.html</a></p> +</li> +<li> +<p>Writing programs with NCURSES by Eric Raymond and Zeyd M. +Ben-Halim at <a href= +"http://invisible-island.net/ncurses/ncurses-intro.html" target= +"_top">http://invisible-island.net/ncurses/ncurses-intro.html</a> - +somewhat obsolete. I was inspired by this document and the +structure of this HOWTO follows from the original document</p> +</li> +</ul> +</div> +</div> +</body> +</html> diff --git a/doc/html/announce.html b/doc/html/announce.html new file mode 100644 index 000000000000..f9dae07e5d9a --- /dev/null +++ b/doc/html/announce.html @@ -0,0 +1,600 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"> +<!-- + $Id: announce.html,v 1.51 2006/12/17 23:32:42 tom Exp $ + **************************************************************************** + * Copyright (c) 1998-2005,2006 Free Software Foundation, Inc. * + * * + * Permission is hereby granted, free of charge, to any person obtaining a * + * copy of this software and associated documentation files (the * + * "Software"), to deal in the Software without restriction, including * + * without limitation the rights to use, copy, modify, merge, publish, * + * distribute, distribute with modifications, sublicense, and/or sell * + * copies of the Software, and to permit persons to whom the Software is * + * furnished to do so, subject to the following conditions: * + * * + * The above copyright notice and this permission notice shall be included * + * in all copies or substantial portions of the Software. * + * * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * + * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * + * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * + * * + * Except as contained in this notice, the name(s) of the above copyright * + * holders shall not be used in advertising or otherwise to promote the * + * sale, use or other dealings in this Software without prior written * + * authorization. * + **************************************************************************** +--> +<HTML> +<HEAD> +<TITLE>Announcing ncurses 5.6</TITLE> +<link rev=made href="mailto:bug-ncurses@gnu.org"> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +</HEAD> +<BODY> + +<H1>Announcing ncurses 5.6</H1> + +The ncurses (new curses) library is a free software emulation of +curses in System V Release 4.0, and more. It uses terminfo format, +supports pads and color +and multiple highlights and forms characters and function-key mapping, +and has all the other SYSV-curses enhancements over BSD curses.<P> + +In mid-June 1995, the maintainer of 4.4BSD curses declared that he +considered 4.4BSD curses obsolete, and encouraged the keepers of +Unix releases such as BSD/OS, FreeBSD and NetBSD to switch over to +ncurses.<P> + +The ncurses code was developed under GNU/Linux. +It has been in use for some time with OpenBSD as the system curses library, +and on FreeBSD and NetBSD as an external package. +It should port easily to any ANSI/POSIX-conforming UNIX. +It has even been ported to OS/2 Warp!<P> + +The distribution includes the library and support utilities, including a +terminfo compiler tic(1), a decompiler infocmp(1), clear(1), tput(1), tset(1), +and a termcap conversion tool captoinfo(1). Full manual pages are provided for +the library and tools.<P> + +The ncurses distribution is available via anonymous FTP at +the GNU distribution site +<A HREF="ftp://ftp.gnu.org/gnu/ncurses/">ftp://ftp.gnu.org/gnu/ncurses/</A> . +<br>It is also available at +<A HREF="ftp://invisible-island.net/ncurses/">ftp://invisible-island.net/ncurses/</A> . + +<H1>Release Notes</H1> + +This release is designed to be upward compatible from ncurses 5.0 through 5.5; +very few applications will require recompilation, depending on the platform. +These are the highlights from the change-log since ncurses 5.5 release. +<p> +Interface changes: +<ul> + <li>generate linkable stubs for some macros: + <br> + getbegx, getbegy, getcurx, getcury, getmaxx, getmaxy, getparx, + getpary, getpary, + <br> + and (for libncursesw) + <br> + wgetbkgrnd + +</ul> +New features and improvements: +<ul> + <li>library + <ul> + <li>support hashed databases for the terminal descriptions. + This uses the Berkeley database, has been tested for + several versions on different platforms. + + <li>add <code>use_legacy_coding()</code> function to support + lynx's font-switching feature. + + <li>add extension <code>nofilter()</code>, to cancel a prior + <code>filter()</code> call. + + <li>add/install a package config script, e.g., + <code>ncurses5-config</code> or + <code>ncursesw5-config</code>, according to + configuration options. + + <li>provide ifdef for <code>NCURSES_NOMACROS</code> which + suppresses most macro definitions from curses.h, i.e., + where a macro is defined to override a function to improve + performance. + + <li>make ifdef's consistent in <code>curses.h</code> for the + extended colors so the header file can be used for the + normal curses library. The header file installed for + extended colors is a variation of the wide-character + configuration. + + <li>improve <code>tgetstr()</code> by making the return value + point into the user's buffer, if provided. + + <li>add ifdef's allowing ncurses to be built with + <code>tparm()</code> using either varargs (the existing + status), or using a fixed-parameter list (to match X/Open). + + <li>widen the test for xterm <code>kmous</code> a little to + <code>allow</code> for other + strings than "\E[M", e.g., for <code>xterm-sco</code> + functionality in xterm. + + <li>modify <code>wgetnstr()</code> to return + <code>KEY_RESIZE</code> if a sigwinch occurs. + + <li>move prototypes for wide-character trace functions from + curses.tail to curses.wide to avoid accidental reference to + those if <code>_XOPEN_SOURCE_EXTENDED</code> is defined + without ensuring that <wchar.h> is included. + + <li>change the way shared libraries (other than libtool) are + installed. Rather than copying the build-tree's libraries, + link the shared objects into the install directory. This + makes the <code>--with-rpath</code> option work except with + <code>$(DESTDIR)</code>. + + <li>several improvements for rendering in hpterm. These are + only available if the library is configured using + <code>--enable-xmc-glitch</code>. + + <li>Add <code>NCURSES_NO_HARD_TABS</code> and + <code>NCURSES_NO_MAGIC_COOKIE</code> environment variables + to allow runtime suppression of the related hard-tabs and + xmc-glitch features. + </ul> + + <li>programs: + <ul> + <li>add new test programs: chgat.c, demo_altkeys.c, + echochar.c, foldkeys.c, movewindow.c, redraw.c, (noting + that existing test programs also were modified to test + additional features). + + <li>modify tack to test extended capability function-key + strings. + + <li>modify toe to access termcap data, e.g., via <code>cgetent()</code> + functions, or as a text file if those are not available. + + <li>improve infocmp/tic <code>-f</code> option formatting. + + <li>add <code>toe -a</code> option, to show all databases. + This uses new private interfaces in the ncurses library for + iterating through the list of databases. + + <li>modify <code>MKfallback.sh</code> to use + <code>tic -x</code> when constructing fallback tables to + allow extended capabilities to be retrieved from a fallback entry. + </ul> + + <li>terminal database + <ul> + <li>add terminfo entries for xfce terminal (xfce) and multi gnome terminal (mgt) + <li>add nsterm-16color entry + <li>updated mlterm terminfo entry + <li>add kon, kon2 and jfbterm terminfo entry + <li>remove invis capability from klone+sgr, mainly used by linux entry, since it does not really do this + <li>add ka2, kb1, kb3, kc2 to vt220-keypad as an extension + <li>add shifted up/down arrow codes to xterm-new as kind/kri strings + <li>add hpterm-color terminfo entry + <li>add 256color variants of terminfo entries for programs which are reported to implement this feature + <li>correct order of use-clauses in rxvt-basic entry which made codes for f1-f4 vt100-style rather than vt220-style. + </ul> +</ul> +Major bug fixes: +<ul> + <li>correct a typo in configure <code>--with-bool</code> option for the + case where <code>--without-cxx</code> is used. + + <li>move assignment from environment variable <code>ESCDELAY</code> + from <code>initscr()</code> down to <code>newterm()</code> so the + environment variable affects timeouts for terminals opened with + newterm() as well. + + <li>modify <code>werase</code> to clear multicolumn characters that + extend into a derived window. + + <li>modify <code>wchgat()</code> to mark updated cells as changed so a + refresh will repaint those cells. + + <li>correct logic in <code>wadd_wch()</code> and + <code>wecho_wch()</code>, which did not guard against passing the + multi-column attribute into a call on <code>waddch()</code>, e.g., + using data returned by <code>win_wch()</code> + + <li>fix redrawing of windows other than <code>stdscr</code> using + <code>wredrawln()</code> by touching the corresponding rows in + <code>curscr</code>. + + <li>reduce memory leaks in repeated calls to <code>tgetent()</code> by + remembering the last <code>TERMINAL*</code> value allocated to hold + the corresponding data and freeing that if the + <code>tgetent()</code> result buffer is the same as the previous + call. + + <li>modify <code>read_termtype()</code> so the <code>term_names</code> + data is always allocated as part of the <code>str_table</code>, a + better fix for a memory leak. + + <li>fix <code>wins_nwstr(),</code> which did not handle single-column + non-8bit codes. + + <li>modify <code>wbkgrnd()</code> to avoid clearing the + <code>A_CHARTEXT</code> attribute bits since those record the state + of multicolumn characters. + + <li>improve <code>SIGWINCH</code> handling by postponing its effect + during <code>newterm()</code>, etc., when allocating screens. + + <li>remove 970913 feature for copying subwindows as they are moved in + <code>mvwin()</code>. + + <li>add checks in <code>waddchnstr()</code> and + <code>wadd_wchnstr()</code> to stop copying when a null character + is found. + + <li>add some checks to ensure current position is within scrolling + region before scrolling on a new line. + + <li>add a workaround to ACS mapping to allow applications such as + test/blue.c to use the "PC ROM" characters by masking them with + A_ALTCHARSET. This worked up til 5.5, but was lost in the revision + of legacy coding. +</ul> + +Portability: +<ul> + <li>configure script: + <ul> + <li>new options: + <dl> + + <dt>--with-hashed-db + <dd>Use Berkeley hashed database for storing terminfo data rather than storing + each compiled entry in a separate binary file within a directory + tree. + + <dt>--without-dlsym + <dd>Do not use <code>dlsym()</code> to load GPM dynamically. + + <dt>--with-valgrind + <dd>Simplify building for testing with valgrind. + + <dt>--enable-wgetch-events + <dd>Compile with experimental wgetch-events code. + + <dt>--enable-signed-char + <dd>Store booleans in "signed char" rather than "char". + + </dl> + + <li>improved options: + <dl> + + <dt>--disable-largefile + <dd>make the option work both ways. + + <dt>--with-gpm + <dd>The option now accepts a parameter, + i.e., the name of the dynamic GPM library to load via + <code>dlopen()</code> + + <dt>--disable-symlinks + <dd>The option now allows one to + disable <code>symlink()</code> in <code>tic</code> even when + <code>link()</code> does not work. + + </dl> + + </ul> + + <li>other configure/build issues: <ul> <li>remove special case for + Darwin in <code>CF_XOPEN_SOURCE</code> configure macro. + + <li>add configure check to ensure that <code>SIGWINCH</code> is + defined on platforms such as OS X which exclude that when + <code>_XOPEN_SOURCE,</code> etc., are defined + + <li>use ld's <code>-search_paths_first</code> option on Darwin + to work around odd search rules on that platform. + + <li>improve ifdef's for <code>_POSIX_VDISABLE</code> in tset to + work with Mac OS X. + + <li>modify configure script to ensure that if the C compiler is + used rather than the loader in making shared libraries, the + <code>$(CFLAGS)</code> variable is also used. + + <li>use <code>${CC}</code> rather than <code>${LD}</code> in + shared library rules for IRIX64, Solaris to help ensure + that initialization sections are provided for extra linkage + requirements, e.g., of C++ applications. + + <li>improve some shared-library configure scripting for Linux, + FreeBSD and NetBSD to make + <code>--with-shlib-version</code> work. + + <li>split up dependency of <code>names.c</code> and + <code>codes.c</code> in <code>ncurses/Makefile</code> to + work with parallel make. + + <li>modify <code>MKlib_gen.sh</code> to change + preprocessor-expanded <code>_Bool</code> back to <code>bool</code>. + + <li>modify <code>progs/Makefile.in</code> to make + <code>tput init</code> work properly with cygwin, + i.e., do not pass a <code>.exe</code> in the reference + string used in check_aliases. + </ul> + + <li>library: + <ul> + <li>ignore wide-acs line-drawing characters that + <code>wcwidth()</code> claims are not one-column. This is + a workaround for Solaris' broken locale support. + + <li>reduce name-pollution in <code>term.h</code> by removing + <code>#define</code>'s for HAVE_xxx symbols. + + <li>fix <code>#ifdef</code> in <code>c++/internal.h</code> for + QNX 6.1 + </ul> + + <li>test programs: <ul> <li>modify <code>test/configure</code> script + to allow building test programs with PDCurses/X11. + + <li>modified test programs to allow some to work with NetBSD + curses. Several do not because NetBSD curses implements a + subset of X/Open curses, and also lacks much of SVr4 + additions. But it is enough for comparison. + + <li>improved <code>test/configure</code> to build test/ncurses + on HPUX 11 using the vendor curses. + + <li>change configure script to produce + <code>test/Makefile</code> from data file. + </ul> +</ul> + +<H1>Features of Ncurses</H1> + +The ncurses package is fully compatible with SVr4 (System V Release 4) curses: + +<UL> +<LI>All 257 of the SVr4 calls have been implemented (and are documented). +<LI>Full support for SVr4 curses features including keyboard mapping, color, +forms-drawing with ACS characters, and automatic recognition of keypad +and function keys. +<LI>An emulation of the SVr4 panels library, supporting +a stack of windows with backing store, is included. +<LI>An emulation of the SVr4 menus library, supporting +a uniform but flexible interface for menu programming, is included. +<LI>An emulation of the SVr4 form library, supporting +data collection through on-screen forms, is included. +<LI>Binary terminfo entries generated by the ncurses tic(1) implementation +are bit-for-bit-compatible with the entry format SVr4 curses uses. +<LI>The utilities have options to allow you to filter terminfo +entries for use with less capable <STRONG>curses</STRONG>/<STRONG>terminfo</STRONG> +versions such as the HP/UX and AIX ports.</UL> + +The ncurses package also has many useful extensions over SVr4: + +<UL> +<LI>The API is 8-bit clean and base-level conformant with the X/OPEN curses +specification, XSI curses (that is, it implements all BASE level features, +and most EXTENDED features). +It includes many function calls not supported under SVr4 curses +(but portability of all +calls is documented so you can use the SVr4 subset only). +<LI>Unlike SVr3 curses, ncurses can write to the rightmost-bottommost corner +of the screen if your terminal has an insert-character capability. +<LI>Ada95 and C++ bindings. +<LI>Support for mouse event reporting with X Window xterm +and FreeBSD and OS/2 console windows. +<LI>Extended mouse support via Alessandro Rubini's gpm package. +<LI>The function <CODE>wresize()</CODE> allows you to resize windows, preserving +their data. +<LI>The function <CODE>use_default_colors()</CODE> allows you to +use the terminal's default colors for the default color pair, +achieving the effect of transparent colors. +<LI>The functions <CODE>keyok()</CODE> +and <CODE>define_key()</CODE> allow +you to better control the use of function keys, +e.g., disabling the ncurses KEY_MOUSE, +or by defining more than one control sequence to map to a given key code. +<LI>Support for 16-color terminals, such as aixterm and modern xterm. +<LI>Better cursor-movement optimization. The package now features a +cursor-local-movement computation more efficient than either BSD's +or System V's. +<LI>Super hardware scrolling support. The screen-update code incorporates +a novel, simple, and cheap algorithm that enables it to make optimal +use of hardware scrolling, line-insertion, and line-deletion +for screen-line movements. This algorithm is more powerful than +the 4.4BSD curses quickch() routine. +<LI>Real support for terminals with the magic-cookie glitch. The +screen-update code will refrain from drawing a highlight if the magic- +cookie unattributed spaces required just before the beginning and +after the end would step on a non-space character. It will +automatically shift highlight boundaries when doing so would make it +possible to draw the highlight without changing the visual appearance +of the screen. +<LI>It is possible to generate the library with a list of pre-loaded +fallback entries linked to it so that it can serve those terminal types even +when no terminfo tree or termcap file is accessible (this may be useful +for support of screen-oriented programs that must run in single-user mode). +<LI>The tic(1)/captoinfo utility provided with ncurses has the +ability to translate many termcaps from the XENIX, IBM and +AT&T extension sets. +<LI>A BSD-like tset(1) utility is provided. +<LI>The ncurses library and utilities will automatically read terminfo +entries from $HOME/.terminfo if it exists, and compile to that directory +if it exists and the user has no write access to the system directory. +This feature makes it easier for users to have personal terminfo entries +without giving up access to the system terminfo directory. +<LI>You may specify a path of directories to search for compiled +descriptions with the environment variable TERMINFO_DIRS (this +generalizes the feature provided by TERMINFO under stock System V.) +<LI>In terminfo source files, use capabilities may refer not just to +other entries in the same source file (as in System V) but also to +compiled entries in either the system terminfo directory or the user's +$HOME/.terminfo directory. +<LI>A script (<STRONG>capconvert</STRONG>) is provided to help BSD users +transition from termcap to terminfo. It gathers the information in a +TERMCAP environment variable and/or a ~/.termcap local entries file +and converts it to an equivalent local terminfo tree under $HOME/.terminfo. +<LI>Automatic fallback to the /etc/termcap file can be compiled in +when it is not possible to build a terminfo tree. This feature is neither +fast nor cheap, you don't want to use it unless you have to, +but it's there. +<LI>The table-of-entries utility <STRONG>toe</STRONG> makes it easy for users to +see exactly what terminal types are available on the system. +<LI>The library meets the XSI requirement that every macro entry +point have a corresponding function which may be linked (and will be +prototype-checked) if the macro definition is disabled with +<CODE>#undef</CODE>. +<LI>An HTML "Introduction to Programming with NCURSES" document provides +a narrative introduction to the curses programming interface. +</UL> + +<H1>State of the Package</H1> + +Numerous bugs present in earlier versions have been fixed; the +library is far more reliable than it used to be. Bounds checking in many +`dangerous' entry points has been improved. The code is now type-safe +according to gcc -Wall. The library has been checked for malloc leaks and +arena corruption by the Purify memory-allocation tester.<P> + +The ncurses code has been tested with a wide variety of applications +including (versions starting with those noted): +<DL> +<DT> cdk +<DD> Curses Development Kit +<br> +<A HREF="http://invisible-island.net/cdk/">http://invisible-island.net/cdk/</A> +<br> +<A HREF="http://www.vexus.ca/products/CDK/">http://www.vexus.ca/products/CDK/</a> +<DT> ded +<DD> directory-editor +<br> +<A HREF="http://invisible-island.net/ded/">http://invisible-island.net/ded/</A> +<DT> dialog +<DD> the underlying application used in Slackware's setup, and the basis +for similar applications on GNU/Linux. +<br> +<A HREF="http://invisible-island.net/dialog/">http://invisible-island.net/dialog/</A> +<DT> lynx +<DD> the character-screen WWW browser +<br> +<A HREF="http://lynx.isc.org/release/">http://lynx.isc.org/release/</A> +<DT> Midnight Commander +<DD> file manager +<br> +<A HREF="http://www.ibiblio.org/mc/">http://www.ibiblio.org/mc/</A> +<DT> mutt +<DD> mail utility +<br> +<A HREF="http://www.mutt.org/">http://www.mutt.org/</A> +<DT> ncftp +<DD> file-transfer utility +<br> +<A HREF="http://www.ncftp.com/">http://www.ncftp.com/</A> +<DT> nvi +<DD> New vi versions 1.50 are able to use ncurses versions 1.9.7 and later. +<br> +<A HREF="http://www.bostic.com/vi/">http://www.bostic.com/vi/</A> +<br> +<DT> pinfo +<DD> Lynx-like info browser. +<A HREF="http://dione.ids.pl/~pborys/software/pinfo/">http://dione.ids.pl/~pborys/software/pinfo/</A> +<DT> tin +<DD> newsreader, supporting color, MIME +<A HREF="http://www.tin.org/">http://www.tin.org/</A> +<DT> vh-1.6 +<DD> Volks-Hypertext browser for the Jargon File +<br> +<A HREF="http://www.debian.org/Packages/unstable/text/vh.html">http://www.debian.org/Packages/unstable/text/vh.html</A> +</DL> +as well as some that use ncurses for the terminfo support alone: +<DL> +<DT> minicom +<DD> terminal emulator +<br> +<A HREF="http://alioth.debian.org/projects/minicom/"> +http://alioth.debian.org/projects/minicom/</A> +<DT> vile +<DD> vi-like-emacs +<br> +<A HREF="http://invisible-island.net/vile/">http://invisible-island.net/vile/</A> +</DL> +<P> + +The ncurses distribution includes a selection of test programs (including +a few games). + +<H2>Who's Who and What's What</H2> + +Zeyd Ben-Halim +started it from a previous package pcurses, written by Pavel Curtis. +Eric S. Raymond +continued development. +Jürgen Pfeifer wrote most of the form and menu libraries. +Ongoing work is being done by +<A HREF="mailto:dickey@invisible-island.net">Thomas Dickey</A>. +Thomas Dickey +acts as the maintainer for the Free Software Foundation, +which holds the copyright on ncurses. +Contact the current maintainers at +<A HREF="mailto:bug-ncurses@gnu.org">bug-ncurses@gnu.org</A>. +<P> + +To join the ncurses mailing list, please write email to +<CODE>bug-ncurses-request@gnu.org</CODE> containing the line: +<PRE> + subscribe <name>@<host.domain> +</PRE> + +This list is open to anyone interested in helping with the development and +testing of this package.<P> + +Beta versions of ncurses and patches to the current release are made available at +<A HREF="ftp://invisible-island.net/ncurses/">ftp://invisible-island.net/ncurses/</A> . + +<H2>Future Plans</H2> +<UL> +<LI>Extended-level XPG4 conformance, with internationalization support. +<LI>Ports to more systems, including DOS and Windows. +</UL> +We need people to help with these projects. If you are interested in working +on them, please join the ncurses list. + +<H2>Other Related Resources</H2> + +The distribution provides a newer version of the terminfo-format +terminal description file once maintained by +<A HREF="http://www.catb.org/~esr/terminfo/">Eric Raymond</A> . +Unlike the older version, the termcap and terminfo data are provided +in the same file, and provides several user-definable extensions +beyond the X/Open specification.<P> + +You can find lots of information on terminal-related topics +not covered in the terminfo file at +<A HREF="http://www.cs.utk.edu/~shuford/terminal_index.html">Richard Shuford's +archive</A> . +</BODY> +</HTML> +<!-- +# The following sets edit modes for GNU EMACS +# Local Variables: +# mode:html +# case-fold-search:nil +# fill-column:70 +# End: +--> diff --git a/doc/html/hackguide.html b/doc/html/hackguide.html new file mode 100644 index 000000000000..97d1369170c1 --- /dev/null +++ b/doc/html/hackguide.html @@ -0,0 +1,914 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"> +<!-- + $Id: hackguide.html,v 1.27 2005/12/24 15:37:13 tom Exp $ + **************************************************************************** + * Copyright (c) 1998-2003,2005 Free Software Foundation, Inc. * + * * + * Permission is hereby granted, free of charge, to any person obtaining a * + * copy of this software and associated documentation files (the * + * "Software"), to deal in the Software without restriction, including * + * without limitation the rights to use, copy, modify, merge, publish, * + * distribute, distribute with modifications, sublicense, and/or sell * + * copies of the Software, and to permit persons to whom the Software is * + * furnished to do so, subject to the following conditions: * + * * + * The above copyright notice and this permission notice shall be included * + * in all copies or substantial portions of the Software. * + * * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * + * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * + * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * + * * + * Except as contained in this notice, the name(s) of the above copyright * + * holders shall not be used in advertising or otherwise to promote the * + * sale, use or other dealings in this Software without prior written * + * authorization. * + **************************************************************************** +--> +<HTML> +<HEAD> +<TITLE>A Hacker's Guide to Ncurses Internals</TITLE> +<link rev="made" href="mailto:bugs-ncurses@gnu.org"> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +<!-- +This document is self-contained, *except* that there is one relative link to +the ncurses-intro.html document, expected to be in the same directory with +this one. +--> +</HEAD> +<BODY> + +<H1>A Hacker's Guide to NCURSES</H1> + +<H1>Contents</H1> +<UL> +<LI><A HREF="#abstract">Abstract</A> +<LI><A HREF="#objective">Objective of the Package</A> +<UL> +<LI><A HREF="#whysvr4">Why System V Curses?</A> +<LI><A HREF="#extensions">How to Design Extensions</A> +</UL> +<LI><A HREF="#portability">Portability and Configuration</A> +<LI><A HREF="#documentation">Documentation Conventions</A> +<LI><A HREF="#bugtrack">How to Report Bugs</A> +<LI><A HREF="#ncurslib">A Tour of the Ncurses Library</A> +<UL> +<LI><A HREF="#loverview">Library Overview</A> +<LI><A HREF="#engine">The Engine Room</A> +<LI><A HREF="#input">Keyboard Input</A> +<LI><A HREF="#mouse">Mouse Events</A> +<LI><A HREF="#output">Output and Screen Updating</A> +</UL> +<LI><A HREF="#fmnote">The Forms and Menu Libraries</A> +<LI><A HREF="#tic">A Tour of the Terminfo Compiler</A> +<UL> +<LI><A HREF="#nonuse">Translation of Non-<STRONG>use</STRONG> Capabilities</A> +<LI><A HREF="#uses">Use Capability Resolution</A> +<LI><A HREF="#translation">Source-Form Translation</A> +</UL> +<LI><A HREF="#utils">Other Utilities</A> +<LI><A HREF="#style">Style Tips for Developers</A> +<LI><A HREF="#port">Porting Hints</A> +</UL> + +<H1><A NAME="abstract">Abstract</A></H1> + +This document is a hacker's tour of the <STRONG>ncurses</STRONG> library and utilities. +It discusses design philosophy, implementation methods, and the +conventions used for coding and documentation. It is recommended +reading for anyone who is interested in porting, extending or improving the +package. + +<H1><A NAME="objective">Objective of the Package</A></H1> + +The objective of the <STRONG>ncurses</STRONG> package is to provide a free software API for +character-cell terminals and terminal emulators with the following +characteristics: + +<UL> +<LI>Source-compatible with historical curses implementations (including + the original BSD curses and System V curses. +<LI>Conformant with the XSI Curses standard issued as part of XPG4 by + X/Open. +<LI>High-quality -- stable and reliable code, wide portability, good + packaging, superior documentation. +<LI>Featureful -- should eliminate as much of the drudgery of C interface + programming as possible, freeing programmers to think at a higher + level of design. +</UL> + +These objectives are in priority order. So, for example, source +compatibility with older version must trump featurefulness -- we cannot +add features if it means breaking the portion of the API corresponding +to historical curses versions. + +<H2><A NAME="whysvr4">Why System V Curses?</A></H2> + +We used System V curses as a model, reverse-engineering their API, in +order to fulfill the first two objectives. <P> + +System V curses implementations can support BSD curses programs with +just a recompilation, so by capturing the System V API we also +capture BSD's. <P> + +More importantly for the future, the XSI Curses standard issued by X/Open +is explicitly and closely modeled on System V. So conformance with +System V took us most of the way to base-level XSI conformance. + +<H2><A NAME="extensions">How to Design Extensions</A></H2> + +The third objective (standards conformance) requires that it be easy to +condition source code using <STRONG>ncurses</STRONG> so that the absence of nonstandard +extensions does not break the code. <P> + +Accordingly, we have a policy of associating with each nonstandard extension +a feature macro, so that ncurses client code can use this macro to condition +in or out the code that requires the <STRONG>ncurses</STRONG> extension. <P> + +For example, there is a macro <CODE>NCURSES_MOUSE_VERSION</CODE> which XSI Curses +does not define, but which is defined in the <STRONG>ncurses</STRONG> library header. +You can use this to condition the calls to the mouse API calls. + +<H1><A NAME="portability">Portability and Configuration</A></H1> + +Code written for <STRONG>ncurses</STRONG> may assume an ANSI-standard C compiler and +POSIX-compatible OS interface. It may also assume the presence of a +System-V-compatible <EM>select(2)</EM> call. <P> + +We encourage (but do not require) developers to make the code friendly +to less-capable UNIX environments wherever possible. <P> + +We encourage developers to support OS-specific optimizations and methods +not available under POSIX/ANSI, provided only that: + +<UL> +<LI>All such code is properly conditioned so the build process does not + attempt to compile it under a plain ANSI/POSIX environment. +<LI>Adding such implementation methods does not introduce incompatibilities + in the <STRONG>ncurses</STRONG> API between platforms. +</UL> + +We use GNU <CODE>autoconf(1)</CODE> as a tool to deal with portability issues. +The right way to leverage an OS-specific feature is to modify the autoconf +specification files (configure.in and aclocal.m4) to set up a new feature +macro, which you then use to condition your code. + +<H1><A NAME="documentation">Documentation Conventions</A></H1> + +There are three kinds of documentation associated with this package. Each +has a different preferred format: + +<UL> +<LI>Package-internal files (README, INSTALL, TO-DO etc.) +<LI>Manual pages. +<LI>Everything else (i.e., narrative documentation). +</UL> + +Our conventions are simple: +<OL> +<LI><STRONG>Maintain package-internal files in plain text.</STRONG> + The expected viewer for them <EM>more(1)</EM> or an editor window; there's + no point in elaborate mark-up. + +<LI><STRONG>Mark up manual pages in the man macros.</STRONG> These have to be viewable + through traditional <EM>man(1)</EM> programs. + +<LI><STRONG>Write everything else in HTML.</STRONG> +</OL> + +When in doubt, HTMLize a master and use <EM>lynx(1)</EM> to generate +plain ASCII (as we do for the announcement document). <P> + +The reason for choosing HTML is that it's (a) well-adapted for on-line +browsing through viewers that are everywhere; (b) more easily readable +as plain text than most other mark-ups, if you don't have a viewer; and (c) +carries enough information that you can generate a nice-looking printed +version from it. Also, of course, it make exporting things like the +announcement document to WWW pretty trivial. + +<H1><A NAME="bugtrack">How to Report Bugs</A></H1> + +The <A NAME="bugreport">reporting address for bugs</A> is +<A HREF="mailto:bug-ncurses@gnu.org">bug-ncurses@gnu.org</A>. +This is a majordomo list; to join, write +to <CODE>bug-ncurses-request@gnu.org</CODE> with a message containing the line: +<PRE> + subscribe <name>@<host.domain> +</PRE> + +The <CODE>ncurses</CODE> code is maintained by a small group of +volunteers. While we try our best to fix bugs promptly, we simply +don't have a lot of hours to spend on elementary hand-holding. We rely +on intelligent cooperation from our users. If you think you have +found a bug in <CODE>ncurses</CODE>, there are some steps you can take +before contacting us that will help get the bug fixed quickly. <P> + +In order to use our bug-fixing time efficiently, we put people who +show us they've taken these steps at the head of our queue. This +means that if you don't, you'll probably end up at the tail end and +have to wait a while. + +<OL> +<LI>Develop a recipe to reproduce the bug. +<p> +Bugs we can reproduce are likely to be fixed very quickly, often +within days. The most effective single thing you can do to get a +quick fix is develop a way we can duplicate the bad behavior -- +ideally, by giving us source for a small, portable test program that +breaks the library. (Even better is a keystroke recipe using one of +the test programs provided with the distribution.) + +<LI>Try to reproduce the bug on a different terminal type. <P> + +In our experience, most of the behaviors people report as library bugs +are actually due to subtle problems in terminal descriptions. This is +especially likely to be true if you're using a traditional +asynchronous terminal or PC-based terminal emulator, rather than xterm +or a UNIX console entry. <P> + +It's therefore extremely helpful if you can tell us whether or not your +problem reproduces on other terminal types. Usually you'll have both +a console type and xterm available; please tell us whether or not your +bug reproduces on both. <P> + +If you have xterm available, it is also good to collect xterm reports for +different window sizes. This is especially true if you normally use an +unusual xterm window size -- a surprising number of the bugs we've seen +are either triggered or masked by these. + +<LI>Generate and examine a trace file for the broken behavior. <P> + +Recompile your program with the debugging versions of the libraries. +Insert a <CODE>trace()</CODE> call with the argument set to <CODE>TRACE_UPDATE</CODE>. +(See <A HREF="ncurses-intro.html#debugging">"Writing Programs with +NCURSES"</A> for details on trace levels.) +Reproduce your bug, then look at the trace file to see what the library +was actually doing. <P> + +Another frequent cause of apparent bugs is application coding errors +that cause the wrong things to be put on the virtual screen. Looking +at the virtual-screen dumps in the trace file will tell you immediately if +this is happening, and save you from the possible embarrassment of being +told that the bug is in your code and is your problem rather than ours. <P> + +If the virtual-screen dumps look correct but the bug persists, it's +possible to crank up the trace level to give more and more information +about the library's update actions and the control sequences it issues +to perform them. The test directory of the distribution contains a +tool for digesting these logs to make them less tedious to wade +through. <P> + +Often you'll find terminfo problems at this stage by noticing that the +escape sequences put out for various capabilities are wrong. If not, +you're likely to learn enough to be able to characterize any bug in +the screen-update logic quite exactly. + +<LI>Report details and symptoms, not just interpretations. <P> + +If you do the preceding two steps, it is very likely that you'll discover +the nature of the problem yourself and be able to send us a fix. This +will create happy feelings all around and earn you good karma for the first +time you run into a bug you really can't characterize and fix yourself. <P> + +If you're still stuck, at least you'll know what to tell us. Remember, we +need details. If you guess about what is safe to leave out, you are too +likely to be wrong. <P> + +If your bug produces a bad update, include a trace file. Try to make +the trace at the <EM>least</EM> voluminous level that pins down the +bug. Logs that have been through tracemunch are OK, it doesn't throw +away any information (actually they're better than un-munched ones because +they're easier to read). <P> + +If your bug produces a core-dump, please include a symbolic stack trace +generated by gdb(1) or your local equivalent. <P> + +Tell us about every terminal on which you've reproduced the bug -- and +every terminal on which you can't. Ideally, sent us terminfo sources +for all of these (yours might differ from ours). <P> + +Include your ncurses version and your OS/machine type, of course! You can +find your ncurses version in the <CODE>curses.h</CODE> file. +</OL> + +If your problem smells like a logic error or in cursor movement or +scrolling or a bad capability, there are a couple of tiny test frames +for the library algorithms in the progs directory that may help you +isolate it. These are not part of the normal build, but do have their +own make productions. <P> + +The most important of these is <CODE>mvcur</CODE>, a test frame for the +cursor-movement optimization code. With this program, you can see +directly what control sequences will be emitted for any given cursor +movement or scroll/insert/delete operations. If you think you've got +a bad capability identified, you can disable it and test again. The +program is command-driven and has on-line help. <P> + +If you think the vertical-scroll optimization is broken, or just want to +understand how it works better, build <CODE>hashmap</CODE> and read the +header comments of <CODE>hardscroll.c</CODE> and <CODE>hashmap.c</CODE>; then try +it out. You can also test the hardware-scrolling optimization separately +with <CODE>hardscroll</CODE>. <P> + +<H1><A NAME="ncurslib">A Tour of the Ncurses Library</A></H1> + +<H2><A NAME="loverview">Library Overview</A></H2> + +Most of the library is superstructure -- fairly trivial convenience +interfaces to a small set of basic functions and data structures used +to manipulate the virtual screen (in particular, none of this code +does any I/O except through calls to more fundamental modules +described below). The files +<blockquote> +<CODE> +lib_addch.c +lib_bkgd.c +lib_box.c +lib_chgat.c +lib_clear.c +lib_clearok.c +lib_clrbot.c +lib_clreol.c +lib_colorset.c +lib_data.c +lib_delch.c +lib_delwin.c +lib_echo.c +lib_erase.c +lib_gen.c +lib_getstr.c +lib_hline.c +lib_immedok.c +lib_inchstr.c +lib_insch.c +lib_insdel.c +lib_insstr.c +lib_instr.c +lib_isendwin.c +lib_keyname.c +lib_leaveok.c +lib_move.c +lib_mvwin.c +lib_overlay.c +lib_pad.c +lib_printw.c +lib_redrawln.c +lib_scanw.c +lib_screen.c +lib_scroll.c +lib_scrollok.c +lib_scrreg.c +lib_set_term.c +lib_slk.c +lib_slkatr_set.c +lib_slkatrof.c +lib_slkatron.c +lib_slkatrset.c +lib_slkattr.c +lib_slkclear.c +lib_slkcolor.c +lib_slkinit.c +lib_slklab.c +lib_slkrefr.c +lib_slkset.c +lib_slktouch.c +lib_touch.c +lib_unctrl.c +lib_vline.c +lib_wattroff.c +lib_wattron.c +lib_window.c +</CODE> +</blockquote> +are all in this category. They are very +unlikely to need change, barring bugs or some fundamental +reorganization in the underlying data structures. <P> + +These files are used only for debugging support: +<blockquote> +<code> +lib_trace.c +lib_traceatr.c +lib_tracebits.c +lib_tracechr.c +lib_tracedmp.c +lib_tracemse.c +trace_buf.c +</code> +</blockquote> +It is rather unlikely you will ever need to change these, unless +you want to introduce a new debug trace level for some reason.<P> + +There is another group of files that do direct I/O via <EM>tputs()</EM>, +computations on the terminal capabilities, or queries to the OS +environment, but nevertheless have only fairly low complexity. These +include: +<blockquote> +<code> +lib_acs.c +lib_beep.c +lib_color.c +lib_endwin.c +lib_initscr.c +lib_longname.c +lib_newterm.c +lib_options.c +lib_termcap.c +lib_ti.c +lib_tparm.c +lib_tputs.c +lib_vidattr.c +read_entry.c. +</code> +</blockquote> +They are likely to need revision only if +ncurses is being ported to an environment without an underlying +terminfo capability representation. <P> + +These files +have serious hooks into +the tty driver and signal facilities: +<blockquote> +<code> +lib_kernel.c +lib_baudrate.c +lib_raw.c +lib_tstp.c +lib_twait.c +</code> +</blockquote> +If you run into porting snafus +moving the package to another UNIX, the problem is likely to be in one +of these files. +The file <CODE>lib_print.c</CODE> uses sleep(2) and also +falls in this category.<P> + +Almost all of the real work is done in the files +<blockquote> +<code> +hardscroll.c +hashmap.c +lib_addch.c +lib_doupdate.c +lib_getch.c +lib_mouse.c +lib_mvcur.c +lib_refresh.c +lib_setup.c +lib_vidattr.c +</code> +</blockquote> +Most of the algorithmic complexity in the +library lives in these files. +If there is a real bug in <STRONG>ncurses</STRONG> itself, it's probably here. +We'll tour some of these files in detail +below (see <A HREF="#engine">The Engine Room</A>). <P> + +Finally, there is a group of files that is actually most of the +terminfo compiler. The reason this code lives in the <STRONG>ncurses</STRONG> +library is to support fallback to /etc/termcap. These files include +<blockquote> +<code> +alloc_entry.c +captoinfo.c +comp_captab.c +comp_error.c +comp_hash.c +comp_parse.c +comp_scan.c +parse_entry.c +read_termcap.c +write_entry.c +</code> +</blockquote> +We'll discuss these in the compiler tour. + +<H2><A NAME="engine">The Engine Room</A></H2> + +<H3><A NAME="input">Keyboard Input</A></H3> + +All <CODE>ncurses</CODE> input funnels through the function +<CODE>wgetch()</CODE>, defined in <CODE>lib_getch.c</CODE>. This function is +tricky; it has to poll for keyboard and mouse events and do a running +match of incoming input against the set of defined special keys. <P> + +The central data structure in this module is a FIFO queue, used to +match multiple-character input sequences against special-key +capabilities; also to implement pushback via <CODE>ungetch()</CODE>. <P> + +The <CODE>wgetch()</CODE> code distinguishes between function key +sequences and the same sequences typed manually by doing a timed wait +after each input character that could lead a function key sequence. +If the entire sequence takes less than 1 second, it is assumed to have +been generated by a function key press. <P> + +Hackers bruised by previous encounters with variant <CODE>select(2)</CODE> +calls may find the code in <CODE>lib_twait.c</CODE> interesting. It deals +with the problem that some BSD selects don't return a reliable +time-left value. The function <CODE>timed_wait()</CODE> effectively +simulates a System V select. + +<H3><A NAME="mouse">Mouse Events</A></H3> + +If the mouse interface is active, <CODE>wgetch()</CODE> polls for mouse +events each call, before it goes to the keyboard for input. It is +up to <CODE>lib_mouse.c</CODE> how the polling is accomplished; it may vary +for different devices. <P> + +Under xterm, however, mouse event notifications come in via the keyboard +input stream. They are recognized by having the <STRONG>kmous</STRONG> capability +as a prefix. This is kind of klugey, but trying to wire in recognition of +a mouse key prefix without going through the function-key machinery would +be just too painful, and this turns out to imply having the prefix somewhere +in the function-key capabilities at terminal-type initialization. <P> + +This kluge only works because <STRONG>kmous</STRONG> isn't actually used by any +historic terminal type or curses implementation we know of. Best +guess is it's a relic of some forgotten experiment in-house at Bell +Labs that didn't leave any traces in the publicly-distributed System V +terminfo files. If System V or XPG4 ever gets serious about using it +again, this kluge may have to change. <P> + +Here are some more details about mouse event handling: <P> + +The <CODE>lib_mouse()</CODE>code is logically split into a lower level that +accepts event reports in a device-dependent format and an upper level that +parses mouse gestures and filters events. The mediating data structure is a +circular queue of event structures. <P> + +Functionally, the lower level's job is to pick up primitive events and +put them on the circular queue. This can happen in one of two ways: +either (a) <CODE>_nc_mouse_event()</CODE> detects a series of incoming +mouse reports and queues them, or (b) code in <CODE>lib_getch.c</CODE> detects the +<STRONG>kmous</STRONG> prefix in the keyboard input stream and calls _nc_mouse_inline +to queue up a series of adjacent mouse reports. <P> + +In either case, <CODE>_nc_mouse_parse()</CODE> should be called after the +series is accepted to parse the digested mouse reports (low-level +events) into a gesture (a high-level or composite event). + +<H3><A NAME="output">Output and Screen Updating</A></H3> + +With the single exception of character echoes during a <CODE>wgetnstr()</CODE> +call (which simulates cooked-mode line editing in an ncurses window), +the library normally does all its output at refresh time. <P> + +The main job is to go from the current state of the screen (as represented +in the <CODE>curscr</CODE> window structure) to the desired new state (as +represented in the <CODE>newscr</CODE> window structure), while doing as +little I/O as possible. <P> + +The brains of this operation are the modules <CODE>hashmap.c</CODE>, +<CODE>hardscroll.c</CODE> and <CODE>lib_doupdate.c</CODE>; the latter two use +<CODE>lib_mvcur.c</CODE>. Essentially, what happens looks like this: <P> + +The <CODE>hashmap.c</CODE> module tries to detect vertical motion +changes between the real and virtual screens. This information +is represented by the oldindex members in the newscr structure. +These are modified by vertical-motion and clear operations, and both are +re-initialized after each update. To this change-journalling +information, the hashmap code adds deductions made using a modified Heckel +algorithm on hash values generated from the line contents. <P> + +The <CODE>hardscroll.c</CODE> module computes an optimum set of scroll, +insertion, and deletion operations to make the indices match. It calls +<CODE>_nc_mvcur_scrolln()</CODE> in <CODE>lib_mvcur.c</CODE> to do those motions. <P> + +Then <CODE>lib_doupdate.c</CODE> goes to work. Its job is to do line-by-line +transformations of <CODE>curscr</CODE> lines to <CODE>newscr</CODE> lines. Its main +tool is the routine <CODE>mvcur()</CODE> in <CODE>lib_mvcur.c</CODE>. This routine +does cursor-movement optimization, attempting to get from given screen +location A to given location B in the fewest output characters possible. <P> + +If you want to work on screen optimizations, you should use the fact +that (in the trace-enabled version of the library) enabling the +<CODE>TRACE_TIMES</CODE> trace level causes a report to be emitted after +each screen update giving the elapsed time and a count of characters +emitted during the update. You can use this to tell when an update +optimization improves efficiency. <P> + +In the trace-enabled version of the library, it is also possible to disable +and re-enable various optimizations at runtime by tweaking the variable +<CODE>_nc_optimize_enable</CODE>. See the file <CODE>include/curses.h.in</CODE> +for mask values, near the end. + +<H1><A NAME="fmnote">The Forms and Menu Libraries</A></H1> + +The forms and menu libraries should work reliably in any environment you +can port ncurses to. The only portability issue anywhere in them is what +flavor of regular expressions the built-in form field type TYPE_REGEXP +will recognize. <P> + +The configuration code prefers the POSIX regex facility, modeled on +System V's, but will settle for BSD regexps if the former isn't available. <P> + +Historical note: the panels code was written primarily to assist in +porting u386mon 2.0 (comp.sources.misc v14i001-4) to systems lacking +panels support; u386mon 2.10 and beyond use it. This version has been +slightly cleaned up for <CODE>ncurses</CODE>. + +<H1><A NAME="tic">A Tour of the Terminfo Compiler</A></H1> + +The <STRONG>ncurses</STRONG> implementation of <STRONG>tic</STRONG> is rather complex +internally; it has to do a trying combination of missions. This starts +with the fact that, in addition to its normal duty of compiling +terminfo sources into loadable terminfo binaries, it has to be able to +handle termcap syntax and compile that too into terminfo entries. <P> + +The implementation therefore starts with a table-driven, dual-mode +lexical analyzer (in <CODE>comp_scan.c</CODE>). The lexer chooses its +mode (termcap or terminfo) based on the first `,' or `:' it finds in +each entry. The lexer does all the work of recognizing capability +names and values; the grammar above it is trivial, just "parse entries +till you run out of file". + +<H2><A NAME="nonuse">Translation of Non-<STRONG>use</STRONG> Capabilities</A></H2> + +Translation of most things besides <STRONG>use</STRONG> capabilities is pretty +straightforward. The lexical analyzer's tokenizer hands each capability +name to a hash function, which drives a table lookup. The table entry +yields an index which is used to look up the token type in another table, +and controls interpretation of the value. <P> + +One possibly interesting aspect of the implementation is the way the +compiler tables are initialized. All the tables are generated by various +awk/sed/sh scripts from a master table <CODE>include/Caps</CODE>; these +scripts actually write C initializers which are linked to the compiler. +Furthermore, the hash table is generated in the same way, so it doesn't +have to be generated at compiler startup time (another benefit of this +organization is that the hash table can be in shareable text space). <P> + +Thus, adding a new capability is usually pretty trivial, just a matter +of adding one line to the <CODE>include/Caps</CODE> file. We'll have more +to say about this in the section on <A HREF="#translation">Source-Form +Translation</A>. + +<H2><A NAME="uses">Use Capability Resolution</A></H2> + +The background problem that makes <STRONG>tic</STRONG> tricky isn't the capability +translation itself, it's the resolution of <STRONG>use</STRONG> capabilities. Older +versions would not handle forward <STRONG>use</STRONG> references for this reason +(that is, a using terminal always had to follow its use target in the +source file). By doing this, they got away with a simple implementation +tactic; compile everything as it blows by, then resolve uses from compiled +entries. <P> + +This won't do for <STRONG>ncurses</STRONG>. The problem is that that the whole +compilation process has to be embeddable in the <STRONG>ncurses</STRONG> library +so that it can be called by the startup code to translate termcap +entries on the fly. The embedded version can't go promiscuously writing +everything it translates out to disk -- for one thing, it will typically +be running with non-root permissions. <P> + +So our <STRONG>tic</STRONG> is designed to parse an entire terminfo file into a +doubly-linked circular list of entry structures in-core, and then do +<STRONG>use</STRONG> resolution in-memory before writing everything out. This +design has other advantages: it makes forward and back use-references +equally easy (so we get the latter for free), and it makes checking for +name collisions before they're written out easy to do. <P> + +And this is exactly how the embedded version works. But the stand-alone +user-accessible version of <STRONG>tic</STRONG> partly reverts to the historical +strategy; it writes to disk (not keeping in core) any entry with no +<STRONG>use</STRONG> references. <P> + +This is strictly a core-economy kluge, implemented because the +terminfo master file is large enough that some core-poor systems swap +like crazy when you compile it all in memory...there have been reports of +this process taking <STRONG>three hours</STRONG>, rather than the twenty seconds +or less typical on the author's development box. <P> + +So. The executable <STRONG>tic</STRONG> passes the entry-parser a hook that +<EM>immediately</EM> writes out the referenced entry if it has no use +capabilities. The compiler main loop refrains from adding the entry +to the in-core list when this hook fires. If some other entry later +needs to reference an entry that got written immediately, that's OK; +the resolution code will fetch it off disk when it can't find it in +core. <P> + +Name collisions will still be detected, just not as cleanly. The +<CODE>write_entry()</CODE> code complains before overwriting an entry that +postdates the time of <STRONG>tic</STRONG>'s first call to +<CODE>write_entry()</CODE>, Thus it will complain about overwriting +entries newly made during the <STRONG>tic</STRONG> run, but not about +overwriting ones that predate it. + +<H2><A NAME="translation">Source-Form Translation</A></H2> + +Another use of <STRONG>tic</STRONG> is to do source translation between various termcap +and terminfo formats. There are more variants out there than you might +think; the ones we know about are described in the <STRONG>captoinfo(1)</STRONG> +manual page. <P> + +The translation output code (<CODE>dump_entry()</CODE> in +<CODE>ncurses/dump_entry.c</CODE>) is shared with the <STRONG>infocmp(1)</STRONG> +utility. It takes the same internal representation used to generate +the binary form and dumps it to standard output in a specified +format. <P> + +The <CODE>include/Caps</CODE> file has a header comment describing ways you +can specify source translations for nonstandard capabilities just by +altering the master table. It's possible to set up capability aliasing +or tell the compiler to plain ignore a given capability without writing +any C code at all. <P> + +For circumstances where you need to do algorithmic translation, there +are functions in <CODE>parse_entry.c</CODE> called after the parse of each +entry that are specifically intended to encapsulate such +translations. This, for example, is where the AIX <STRONG>box1</STRONG> capability +get translated to an <STRONG>acsc</STRONG> string. + +<H1><A NAME="utils">Other Utilities</A></H1> + +The <STRONG>infocmp</STRONG> utility is just a wrapper around the same +entry-dumping code used by <STRONG>tic</STRONG> for source translation. Perhaps +the one interesting aspect of the code is the use of a predicate +function passed in to <CODE>dump_entry()</CODE> to control which +capabilities are dumped. This is necessary in order to handle both +the ordinary De-compilation case and entry difference reporting. <P> + +The <STRONG>tput</STRONG> and <STRONG>clear</STRONG> utilities just do an entry load +followed by a <CODE>tputs()</CODE> of a selected capability. + +<H1><A NAME="style">Style Tips for Developers</A></H1> + +See the TO-DO file in the top-level directory of the source distribution +for additions that would be particularly useful. <P> + +The prefix <CODE>_nc_</CODE> should be used on library public functions that are +not part of the curses API in order to prevent pollution of the +application namespace. + +If you have to add to or modify the function prototypes in curses.h.in, +read ncurses/MKlib_gen.sh first so you can avoid breaking XSI conformance. + +Please join the ncurses mailing list. See the INSTALL file in the +top level of the distribution for details on the list. <P> + +Look for the string <CODE>FIXME</CODE> in source files to tag minor bugs +and potential problems that could use fixing. <P> + +Don't try to auto-detect OS features in the main body of the C code. +That's the job of the configuration system. <P> + +To hold down complexity, do make your code data-driven. Especially, +if you can drive logic from a table filtered out of +<CODE>include/Caps</CODE>, do it. If you find you need to augment the +data in that file in order to generate the proper table, that's still +preferable to ad-hoc code -- that's why the fifth field (flags) is +there. <P> + +Have fun! + +<H1><A NAME="port">Porting Hints</A></H1> + +The following notes are intended to be a first step towards DOS and Macintosh +ports of the ncurses libraries. <P> + +The following library modules are `pure curses'; they operate only on +the curses internal structures, do all output through other curses +calls (not including <CODE>tputs()</CODE> and <CODE>putp()</CODE>) and do not +call any other UNIX routines such as signal(2) or the stdio library. +Thus, they should not need to be modified for single-terminal +ports. + +<blockquote> +<code> +lib_addch.c +lib_addstr.c +lib_bkgd.c +lib_box.c +lib_clear.c +lib_clrbot.c +lib_clreol.c +lib_delch.c +lib_delwin.c +lib_erase.c +lib_inchstr.c +lib_insch.c +lib_insdel.c +lib_insstr.c +lib_keyname.c +lib_move.c +lib_mvwin.c +lib_newwin.c +lib_overlay.c +lib_pad.c +lib_printw.c +lib_refresh.c +lib_scanw.c +lib_scroll.c +lib_scrreg.c +lib_set_term.c +lib_touch.c +lib_tparm.c +lib_tputs.c +lib_unctrl.c +lib_window.c +panel.c +</code> +</blockquote> +<P> + +This module is pure curses, but calls outstr(): + +<blockquote> +<code> +lib_getstr.c +</code> +</blockquote> +<P> + +These modules are pure curses, except that they use <CODE>tputs()</CODE> +and <CODE>putp()</CODE>: + +<blockquote> +<code> +lib_beep.c +lib_color.c +lib_endwin.c +lib_options.c +lib_slk.c +lib_vidattr.c +</code> +</blockquote> +<P> + +This modules assist in POSIX emulation on non-POSIX systems: +<DL> +<DT> sigaction.c +<DD> signal calls +</DL> + +The following source files will not be needed for a +single-terminal-type port. + +<blockquote> +<code> +alloc_entry.c +captoinfo.c +clear.c +comp_captab.c +comp_error.c +comp_hash.c +comp_main.c +comp_parse.c +comp_scan.c +dump_entry.c +infocmp.c +parse_entry.c +read_entry.c +tput.c +write_entry.c +</code> +</blockquote> +<P> + +The following modules will use open()/read()/write()/close()/lseek() on files, +but no other OS calls. + +<DL> +<DT>lib_screen.c +<DD>used to read/write screen dumps +<DT>lib_trace.c +<DD>used to write trace data to the logfile +</DL> + +Modules that would have to be modified for a port start here: <P> + +The following modules are `pure curses' but contain assumptions inappropriate +for a memory-mapped port. + +<dl> +<dt>lib_longname.c<dd>assumes there may be multiple terminals +<dt>lib_acs.c<dd>assumes acs_map as a double indirection +<dt>lib_mvcur.c<dd>assumes cursor moves have variable cost +<dt>lib_termcap.c<dd>assumes there may be multiple terminals +<dt>lib_ti.c<dd>assumes there may be multiple terminals +</dl> + +The following modules use UNIX-specific calls: + +<dl> +<dt>lib_doupdate.c<dd>input checking +<dt>lib_getch.c<dd>read() +<dt>lib_initscr.c<dd>getenv() +<dt>lib_newterm.c +<dt>lib_baudrate.c +<dt>lib_kernel.c<dd>various tty-manipulation and system calls +<dt>lib_raw.c<dd>various tty-manipulation calls +<dt>lib_setup.c<dd>various tty-manipulation calls +<dt>lib_restart.c<dd>various tty-manipulation calls +<dt>lib_tstp.c<dd>signal-manipulation calls +<dt>lib_twait.c<dd>gettimeofday(), select(). +</dl> + +<HR> +<ADDRESS>Eric S. Raymond <esr@snark.thyrsus.com></ADDRESS> +(Note: This is <EM>not</EM> the <A HREF="#bugtrack">bug address</A>!) +</BODY> +</HTML> diff --git a/doc/html/ncurses-intro.html b/doc/html/ncurses-intro.html new file mode 100644 index 000000000000..451e7ab4d32d --- /dev/null +++ b/doc/html/ncurses-intro.html @@ -0,0 +1,2722 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"> +<!-- + $Id: ncurses-intro.html,v 1.43 2007/03/03 19:31:50 tom Exp $ + **************************************************************************** + * Copyright (c) 1998-2006,2007 Free Software Foundation, Inc. * + * * + * Permission is hereby granted, free of charge, to any person obtaining a * + * copy of this software and associated documentation files (the * + * "Software"), to deal in the Software without restriction, including * + * without limitation the rights to use, copy, modify, merge, publish, * + * distribute, distribute with modifications, sublicense, and/or sell * + * copies of the Software, and to permit persons to whom the Software is * + * furnished to do so, subject to the following conditions: * + * * + * The above copyright notice and this permission notice shall be included * + * in all copies or substantial portions of the Software. * + * * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * + * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * + * THE USE OR OTHER DEALINGS IN THE SOFTWARE. * + * * + * Except as contained in this notice, the name(s) of the above copyright * + * holders shall not be used in advertising or otherwise to promote the * + * sale, use or other dealings in this Software without prior written * + * authorization. * + **************************************************************************** +--> +<HTML> +<HEAD> +<TITLE>Writing Programs with NCURSES</TITLE> +<link rev="made" href="mailto:bugs-ncurses@gnu.org"> +<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> +</HEAD> +<BODY> + +<H1>Writing Programs with NCURSES</H1> + +<BLOCKQUOTE> +by Eric S. Raymond and Zeyd M. Ben-Halim<BR> +updates since release 1.9.9e by Thomas Dickey +</BLOCKQUOTE> + +<H1>Contents</H1> +<UL> +<LI><A HREF="#introduction">Introduction</A> +<UL> +<LI><A HREF="#history">A Brief History of Curses</A> +<LI><A HREF="#scope">Scope of This Document</A> +<LI><A HREF="#terminology">Terminology</A> +</UL> +<LI><A HREF="#curses">The Curses Library</A> +<UL> +<LI><A HREF="#overview">An Overview of Curses</A> +<UL> +<LI><A HREF="#compiling">Compiling Programs using Curses</A> +<LI><A HREF="#updating">Updating the Screen</A> +<LI><A HREF="#stdscr">Standard Windows and Function Naming Conventions</A> +<LI><A HREF="#variables">Variables</A> +</UL> +<LI><A HREF="#using">Using the Library</A> +<UL> +<LI><A HREF="#starting">Starting up</A> +<LI><A HREF="#output">Output</A> +<LI><A HREF="#input">Input</A> +<LI><A HREF="#formschars">Using Forms Characters</A> +<LI><A HREF="#attributes">Character Attributes and Color</A> +<LI><A HREF="#mouse">Mouse Interfacing</A> +<LI><A HREF="#finishing">Finishing Up</A> +</UL> +<LI><A HREF="#functions">Function Descriptions</A> +<UL> +<LI><A HREF="#init">Initialization and Wrapup</A> +<LI><A HREF="#flush">Causing Output to the Terminal</A> +<LI><A HREF="#lowlevel">Low-Level Capability Access</A> +<LI><A HREF="#debugging">Debugging</A> +</UL> +<LI><A HREF="#hints">Hints, Tips, and Tricks</A> +<UL> +<LI><A HREF="#caution">Some Notes of Caution</A> +<LI><A HREF="#leaving">Temporarily Leaving ncurses Mode</A> +<LI><A HREF="#xterm">Using <CODE>ncurses</CODE> under <CODE>xterm</CODE></A> +<LI><A HREF="#screens">Handling Multiple Terminal Screens</A> +<LI><A HREF="#testing">Testing for Terminal Capabilities</A> +<LI><A HREF="#tuning">Tuning for Speed</A> +<LI><A HREF="#special">Special Features of <CODE>ncurses</CODE></A> +</UL> +<LI><A HREF="#compat">Compatibility with Older Versions</A> +<UL> +<LI><A HREF="#refbug">Refresh of Overlapping Windows</A> +<LI><A HREF="#backbug">Background Erase</A> +</UL> +<LI><A HREF="#xsifuncs">XSI Curses Conformance</A> +</UL> +<LI><A HREF="#panels">The Panels Library</A> +<UL> +<LI><A HREF="#pcompile">Compiling With the Panels Library</A> +<LI><A HREF="#poverview">Overview of Panels</A> +<LI><A HREF="#pstdscr">Panels, Input, and the Standard Screen</A> +<LI><A HREF="#hiding">Hiding Panels</A> +<LI><A HREF="#pmisc">Miscellaneous Other Facilities</A> +</UL> +<LI><A HREF="#menu">The Menu Library</A> +<UL> +<LI><A HREF="#mcompile">Compiling with the menu Library</A> +<LI><A HREF="#moverview">Overview of Menus</A> +<LI><A HREF="#mselect">Selecting items</A> +<LI><A HREF="#mdisplay">Menu Display</A> +<LI><A HREF="#mwindows">Menu Windows</A> +<LI><A HREF="#minput">Processing Menu Input</A> +<LI><A HREF="#mmisc">Miscellaneous Other Features</A> +</UL> +<LI><A HREF="#form">The Forms Library</A> +<UL> +<LI><A HREF="#fcompile">Compiling with the forms Library</A> +<LI><A HREF="#foverview">Overview of Forms</A> +<LI><A HREF="#fcreate">Creating and Freeing Fields and Forms</A> +<LI><A HREF="#fattributes">Fetching and Changing Field Attributes</A> +<UL> +<LI><A HREF="#fsizes">Fetching Size and Location Data</A> +<LI><A HREF="#flocation">Changing the Field Location</A> +<LI><A HREF="#fjust">The Justification Attribute</A> +<LI><A HREF="#fdispatts">Field Display Attributes</A> +<LI><A HREF="#foptions">Field Option Bits</A> +<LI><A HREF="#fstatus">Field Status</A> +<LI><A HREF="#fuser">Field User Pointer</A> +</UL> +<LI><A HREF="#fdynamic">Variable-Sized Fields</A> +<LI><A HREF="#fvalidation">Field Validation</A> +<UL> +<LI><A HREF="#ftype_alpha">TYPE_ALPHA</A> +<LI><A HREF="#ftype_alnum">TYPE_ALNUM</A> +<LI><A HREF="#ftype_enum">TYPE_ENUM</A> +<LI><A HREF="#ftype_integer">TYPE_INTEGER</A> +<LI><A HREF="#ftype_numeric">TYPE_NUMERIC</A> +<LI><A HREF="#ftype_regexp">TYPE_REGEXP</A> +</UL> +<LI><A HREF="#fbuffer">Direct Field Buffer Manipulation</A> +<LI><A HREF="#formattrs">Attributes of Forms</A> +<LI><A HREF="#fdisplay">Control of Form Display</A> +<LI><A HREF="#fdriver">Input Processing in the Forms Driver</A> +<UL> +<LI><A HREF="#fpage">Page Navigation Requests</A> +<LI><A HREF="#ffield">Inter-Field Navigation Requests</A> +<LI><A HREF="#fifield">Intra-Field Navigation Requests</A> +<LI><A HREF="#fscroll">Scrolling Requests</A> +<LI><A HREF="#fedit">Field Editing Requests</A> +<LI><A HREF="#forder">Order Requests</A> +<LI><A HREF="#fappcmds">Application Commands</A> +</UL> +<LI><A HREF="#fhooks">Field Change Hooks</A> +<LI><A HREF="#ffocus">Field Change Commands</A> +<LI><A HREF="#frmoptions">Form Options</A> +<LI><A HREF="#fcustom">Custom Validation Types</A> +<UL> +<LI><A HREF="#flinktypes">Union Types</A> +<LI><A HREF="#fnewtypes">New Field Types</A> +<LI><A HREF="#fcheckargs">Validation Function Arguments</A> +<LI><A HREF="#fcustorder">Order Functions For Custom Types</A> +<LI><A HREF="#fcustprobs">Avoiding Problems</A> +</UL> +</UL> +</UL> + +<HR> +<H1><A NAME="introduction">Introduction</A></H1> + +This document is an introduction to programming with <CODE>curses</CODE>. It is +not an exhaustive reference for the curses Application Programming Interface +(API); that role is filled by the <CODE>curses</CODE> manual pages. Rather, it +is intended to help C programmers ease into using the package. <P> + +This document is aimed at C applications programmers not yet specifically +familiar with ncurses. If you are already an experienced <CODE>curses</CODE> +programmer, you should nevertheless read the sections on +<A HREF="#mouse">Mouse Interfacing</A>, <A HREF="#debugging">Debugging</A>, +<A HREF="#compat">Compatibility with Older Versions</A>, +and <A HREF="#hints">Hints, Tips, and Tricks</A>. These will bring you up +to speed on the special features and quirks of the <CODE>ncurses</CODE> +implementation. If you are not so experienced, keep reading. <P> + +The <CODE>curses</CODE> package is a subroutine library for +terminal-independent screen-painting and input-event handling which +presents a high level screen model to the programmer, hiding differences +between terminal types and doing automatic optimization of output to change +one screen full of text into another. <CODE>Curses</CODE> uses terminfo, which +is a database format that can describe the capabilities of thousands of +different terminals. <P> + +The <CODE>curses</CODE> API may seem something of an archaism on UNIX desktops +increasingly dominated by X, Motif, and Tcl/Tk. Nevertheless, UNIX still +supports tty lines and X supports <EM>xterm(1)</EM>; the <CODE>curses</CODE> +API has the advantage of (a) back-portability to character-cell terminals, +and (b) simplicity. For an application that does not require bit-mapped +graphics and multiple fonts, an interface implementation using <CODE>curses</CODE> +will typically be a great deal simpler and less expensive than one using an +X toolkit. + +<H2><A NAME="history">A Brief History of Curses</A></H2> + +Historically, the first ancestor of <CODE>curses</CODE> was the routines written to +provide screen-handling for the game <CODE>rogue</CODE>; these used the +already-existing <CODE>termcap</CODE> database facility for describing terminal +capabilities. These routines were abstracted into a documented library and +first released with the early BSD UNIX versions. <P> + +System III UNIX from Bell Labs featured a rewritten and much-improved +<CODE>curses</CODE> library. It introduced the terminfo format. Terminfo is based +on Berkeley's termcap database, but contains a number of improvements and +extensions. Parameterized capabilities strings were introduced, making it +possible to describe multiple video attributes, and colors and to handle far +more unusual terminals than possible with termcap. In the later AT&T +System V releases, <CODE>curses</CODE> evolved to use more facilities and offer +more capabilities, going far beyond BSD curses in power and flexibility. + +<H2><A NAME="scope">Scope of This Document</A></H2> + +This document describes <CODE>ncurses</CODE>, a free implementation of +the System V <CODE>curses</CODE> API with some clearly marked extensions. +It includes the following System V curses features: +<UL> +<LI>Support for multiple screen highlights (BSD curses could only +handle one `standout' highlight, usually reverse-video). +<LI>Support for line- and box-drawing using forms characters. +<LI>Recognition of function keys on input. +<LI>Color support. +<LI>Support for pads (windows of larger than screen size on which the +screen or a subwindow defines a viewport). +</UL> + +Also, this package makes use of the insert and delete line and character +features of terminals so equipped, and determines how to optimally use these +features with no help from the programmer. It allows arbitrary combinations of +video attributes to be displayed, even on terminals that leave ``magic +cookies'' on the screen to mark changes in attributes. <P> + +The <CODE>ncurses</CODE> package can also capture and use event reports from a +mouse in some environments (notably, xterm under the X window system). This +document includes tips for using the mouse. <P> + +The <CODE>ncurses</CODE> package was originated by Pavel Curtis. The original +maintainer of this package is +<A HREF="mailto:zmbenhal@netcom.com">Zeyd Ben-Halim</A> +<zmbenhal@netcom.com>. +<A HREF="mailto:esr@snark.thyrsus.com">Eric S. Raymond</A> +<esr@snark.thyrsus.com> +wrote many of the new features in versions after 1.8.1 +and wrote most of this introduction. +Jürgen Pfeifer +wrote all of the menu and forms code as well as the +<A HREF="http://www.adahome.com">Ada95</A> binding. +Ongoing work is being done by +<A HREF="mailto:dickey@invisible-island.net">Thomas Dickey</A> (maintainer). +Contact the current maintainers at +<A HREF="mailto:bug-ncurses@gnu.org">bug-ncurses@gnu.org</A>. +<P> + +This document also describes the <A HREF="#panels">panels</A> extension library, +similarly modeled on the SVr4 panels facility. This library allows you to +associate backing store with each of a stack or deck of overlapping windows, +and provides operations for moving windows around in the stack that change +their visibility in the natural way (handling window overlaps). <P> + +Finally, this document describes in detail the <A HREF="#menu">menus</A> and <A +HREF="#form">forms</A> extension libraries, also cloned from System V, +which support easy construction and sequences of menus and fill-in +forms. + + +<H2><A NAME="terminology">Terminology</A></H2> + +In this document, the following terminology is used with reasonable +consistency: + +<DL> +<DT> window +<DD> +A data structure describing a sub-rectangle of the screen (possibly the +entire screen). You can write to a window as though it were a miniature +screen, scrolling independently of other windows on the physical screen. +<DT> screens +<DD> +A subset of windows which are as large as the terminal screen, i.e., they start +at the upper left hand corner and encompass the lower right hand corner. One +of these, <CODE>stdscr</CODE>, is automatically provided for the programmer. +<DT> terminal screen +<DD> +The package's idea of what the terminal display currently looks like, i.e., +what the user sees now. This is a special screen. +</DL> + +<H1><A NAME="curses">The Curses Library</A></H1> + +<H2><A NAME="overview">An Overview of Curses</A></H2> + +<H3><A NAME="compiling">Compiling Programs using Curses</A></H3> + +In order to use the library, it is necessary to have certain types and +variables defined. Therefore, the programmer must have a line: + +<PRE> + #include <curses.h> +</PRE> + +at the top of the program source. The screen package uses the Standard I/O +library, so <CODE><curses.h></CODE> includes +<CODE><stdio.h></CODE>. <CODE><curses.h></CODE> also includes +<CODE><termios.h></CODE>, <CODE><termio.h></CODE>, or +<CODE><sgtty.h></CODE> depending on your system. It is redundant (but +harmless) for the programmer to do these includes, too. In linking with +<CODE>curses</CODE> you need to have <CODE>-lncurses</CODE> in your LDFLAGS or on the +command line. There is no need for any other libraries. + +<H3><A NAME="updating">Updating the Screen</A></H3> + +In order to update the screen optimally, it is necessary for the routines to +know what the screen currently looks like and what the programmer wants it to +look like next. For this purpose, a data type (structure) named WINDOW is +defined which describes a window image to the routines, including its starting +position on the screen (the (y, x) coordinates of the upper left hand corner) +and its size. One of these (called <CODE>curscr</CODE>, for current screen) is a +screen image of what the terminal currently looks like. Another screen (called +<CODE>stdscr</CODE>, for standard screen) is provided by default to make changes +on. <P> + +A window is a purely internal representation. It is used to build and store a +potential image of a portion of the terminal. It doesn't bear any necessary +relation to what is really on the terminal screen; it's more like a +scratchpad or write buffer. <P> + +To make the section of physical screen corresponding to a window reflect the +contents of the window structure, the routine <CODE>refresh()</CODE> (or +<CODE>wrefresh()</CODE> if the window is not <CODE>stdscr</CODE>) is called. <P> + +A given physical screen section may be within the scope of any number of +overlapping windows. Also, changes can be made to windows in any order, +without regard to motion efficiency. Then, at will, the programmer can +effectively say ``make it look like this,'' and let the package implementation +determine the most efficient way to repaint the screen. + +<H3><A NAME="stdscr">Standard Windows and Function Naming Conventions</A></H3> + +As hinted above, the routines can use several windows, but two are +automatically given: <CODE>curscr</CODE>, which knows what the terminal looks like, +and <CODE>stdscr</CODE>, which is what the programmer wants the terminal to look +like next. The user should never actually access <CODE>curscr</CODE> directly. +Changes should be made to through the API, and then the routine +<CODE>refresh()</CODE> (or <CODE>wrefresh()</CODE>) called. <P> + +Many functions are defined to use <CODE>stdscr</CODE> as a default screen. For +example, to add a character to <CODE>stdscr</CODE>, one calls <CODE>addch()</CODE> with +the desired character as argument. To write to a different window. use the +routine <CODE>waddch()</CODE> (for `w'indow-specific addch()) is provided. This +convention of prepending function names with a `w' when they are to be +applied to specific windows is consistent. The only routines which do not +follow it are those for which a window must always be specified. <P> + +In order to move the current (y, x) coordinates from one point to another, the +routines <CODE>move()</CODE> and <CODE>wmove()</CODE> are provided. However, it is +often desirable to first move and then perform some I/O operation. In order to +avoid clumsiness, most I/O routines can be preceded by the prefix 'mv' and +the desired (y, x) coordinates prepended to the arguments to the function. For +example, the calls + +<PRE> + move(y, x); + addch(ch); +</PRE> + +can be replaced by + +<PRE> + mvaddch(y, x, ch); +</PRE> + +and + +<PRE> + wmove(win, y, x); + waddch(win, ch); +</PRE> + +can be replaced by + +<PRE> + mvwaddch(win, y, x, ch); +</PRE> + +Note that the window description pointer (win) comes before the added (y, x) +coordinates. If a function requires a window pointer, it is always the first +parameter passed. + +<H3><A NAME="variables">Variables</A></H3> + +The <CODE>curses</CODE> library sets some variables describing the terminal +capabilities. + +<PRE> + type name description + ------------------------------------------------------------------ + int LINES number of lines on the terminal + int COLS number of columns on the terminal +</PRE> + +The <CODE>curses.h</CODE> also introduces some <CODE>#define</CODE> constants and types +of general usefulness: + +<DL> +<DT> <CODE>bool</CODE> +<DD> boolean type, actually a `char' (e.g., <CODE>bool doneit;</CODE>) +<DT> <CODE>TRUE</CODE> +<DD> boolean `true' flag (1). +<DT> <CODE>FALSE</CODE> +<DD> boolean `false' flag (0). +<DT> <CODE>ERR</CODE> +<DD> error flag returned by routines on a failure (-1). +<DT> <CODE>OK</CODE> +<DD> error flag returned by routines when things go right. +</DL> + +<H2><A NAME="using">Using the Library</A></H2> + +Now we describe how to actually use the screen package. In it, we assume all +updating, reading, etc. is applied to <CODE>stdscr</CODE>. These instructions will +work on any window, providing you change the function names and parameters as +mentioned above. <P> + +Here is a sample program to motivate the discussion: + +<PRE> +#include <curses.h> +#include <signal.h> + +static void finish(int sig); + +int +main(int argc, char *argv[]) +{ + int num = 0; + + /* initialize your non-curses data structures here */ + + (void) signal(SIGINT, finish); /* arrange interrupts to terminate */ + + (void) initscr(); /* initialize the curses library */ + keypad(stdscr, TRUE); /* enable keyboard mapping */ + (void) nonl(); /* tell curses not to do NL->CR/NL on output */ + (void) cbreak(); /* take input chars one at a time, no wait for \n */ + (void) echo(); /* echo input - in color */ + + if (has_colors()) + { + start_color(); + + /* + * Simple color assignment, often all we need. Color pair 0 cannot + * be redefined. This example uses the same value for the color + * pair as for the foreground color, though of course that is not + * necessary: + */ + init_pair(1, COLOR_RED, COLOR_BLACK); + init_pair(2, COLOR_GREEN, COLOR_BLACK); + init_pair(3, COLOR_YELLOW, COLOR_BLACK); + init_pair(4, COLOR_BLUE, COLOR_BLACK); + init_pair(5, COLOR_CYAN, COLOR_BLACK); + init_pair(6, COLOR_MAGENTA, COLOR_BLACK); + init_pair(7, COLOR_WHITE, COLOR_BLACK); + } + + for (;;) + { + int c = getch(); /* refresh, accept single keystroke of input */ + attrset(COLOR_PAIR(num % 8)); + num++; + + /* process the command keystroke */ + } + + finish(0); /* we're done */ +} + +static void finish(int sig) +{ + endwin(); + + /* do your non-curses wrapup here */ + + exit(0); +} +</PRE> + +<H3><A NAME="starting">Starting up</A></H3> + +In order to use the screen package, the routines must know about terminal +characteristics, and the space for <CODE>curscr</CODE> and <CODE>stdscr</CODE> must be +allocated. These function <CODE>initscr()</CODE> does both these things. Since it +must allocate space for the windows, it can overflow memory when attempting to +do so. On the rare occasions this happens, <CODE>initscr()</CODE> will terminate +the program with an error message. <CODE>initscr()</CODE> must always be called +before any of the routines which affect windows are used. If it is not, the +program will core dump as soon as either <CODE>curscr</CODE> or <CODE>stdscr</CODE> are +referenced. However, it is usually best to wait to call it until after you are +sure you will need it, like after checking for startup errors. Terminal status +changing routines like <CODE>nl()</CODE> and <CODE>cbreak()</CODE> should be called +after <CODE>initscr()</CODE>. <P> + +Once the screen windows have been allocated, you can set them up for +your program. If you want to, say, allow a screen to scroll, use +<CODE>scrollok()</CODE>. If you want the cursor to be left in place after +the last change, use <CODE>leaveok()</CODE>. If this isn't done, +<CODE>refresh()</CODE> will move the cursor to the window's current (y, x) +coordinates after updating it. <P> + +You can create new windows of your own using the functions <CODE>newwin()</CODE>, +<CODE>derwin()</CODE>, and <CODE>subwin()</CODE>. The routine <CODE>delwin()</CODE> will +allow you to get rid of old windows. All the options described above can be +applied to any window. + +<H3><A NAME="output">Output</A></H3> + +Now that we have set things up, we will want to actually update the terminal. +The basic functions used to change what will go on a window are +<CODE>addch()</CODE> and <CODE>move()</CODE>. <CODE>addch()</CODE> adds a character at the +current (y, x) coordinates. <CODE>move()</CODE> changes the current (y, x) +coordinates to whatever you want them to be. It returns <CODE>ERR</CODE> if you +try to move off the window. As mentioned above, you can combine the two into +<CODE>mvaddch()</CODE> to do both things at once. <P> + +The other output functions, such as <CODE>addstr()</CODE> and <CODE>printw()</CODE>, +all call <CODE>addch()</CODE> to add characters to the window. <P> + +After you have put on the window what you want there, when you want the portion +of the terminal covered by the window to be made to look like it, you must call +<CODE>refresh()</CODE>. In order to optimize finding changes, <CODE>refresh()</CODE> +assumes that any part of the window not changed since the last +<CODE>refresh()</CODE> of that window has not been changed on the terminal, i.e., +that you have not refreshed a portion of the terminal with an overlapping +window. If this is not the case, the routine <CODE>touchwin()</CODE> is provided +to make it look like the entire window has been changed, thus making +<CODE>refresh()</CODE> check the whole subsection of the terminal for changes. <P> + +If you call <CODE>wrefresh()</CODE> with <CODE>curscr</CODE> as its argument, it will +make the screen look like <CODE>curscr</CODE> thinks it looks like. This is useful +for implementing a command which would redraw the screen in case it get messed +up. + +<H3><A NAME="input">Input</A></H3> + +The complementary function to <CODE>addch()</CODE> is <CODE>getch()</CODE> which, if +echo is set, will call <CODE>addch()</CODE> to echo the character. Since the +screen package needs to know what is on the terminal at all times, if +characters are to be echoed, the tty must be in raw or cbreak mode. Since +initially the terminal has echoing enabled and is in ordinary ``cooked'' mode, +one or the other has to changed before calling <CODE>getch()</CODE>; otherwise, +the program's output will be unpredictable. <P> + +When you need to accept line-oriented input in a window, the functions +<CODE>wgetstr()</CODE> and friends are available. There is even a <CODE>wscanw()</CODE> +function that can do <CODE>scanf()</CODE>(3)-style multi-field parsing on window +input. These pseudo-line-oriented functions turn on echoing while they +execute. <P> + +The example code above uses the call <CODE>keypad(stdscr, TRUE)</CODE> to enable +support for function-key mapping. With this feature, the <CODE>getch()</CODE> code +watches the input stream for character sequences that correspond to arrow and +function keys. These sequences are returned as pseudo-character values. The +<CODE>#define</CODE> values returned are listed in the <CODE>curses.h</CODE> The +mapping from sequences to <CODE>#define</CODE> values is determined by +<CODE>key_</CODE> capabilities in the terminal's terminfo entry. + +<H3><A NAME="formschars">Using Forms Characters</A></H3> + +The <CODE>addch()</CODE> function (and some others, including <CODE>box()</CODE> and +<CODE>border()</CODE>) can accept some pseudo-character arguments which are specially +defined by <CODE>ncurses</CODE>. These are <CODE>#define</CODE> values set up in +the <CODE>curses.h</CODE> header; see there for a complete list (look for +the prefix <CODE>ACS_</CODE>). <P> + +The most useful of the ACS defines are the forms-drawing characters. You can +use these to draw boxes and simple graphs on the screen. If the terminal +does not have such characters, <CODE>curses.h</CODE> will map them to a +recognizable (though ugly) set of ASCII defaults. + +<H3><A NAME="attributes">Character Attributes and Color</A></H3> + +The <CODE>ncurses</CODE> package supports screen highlights including standout, +reverse-video, underline, and blink. It also supports color, which is treated +as another kind of highlight. <P> + +Highlights are encoded, internally, as high bits of the pseudo-character type +(<CODE>chtype</CODE>) that <CODE>curses.h</CODE> uses to represent the contents of a +screen cell. See the <CODE>curses.h</CODE> header file for a complete list of +highlight mask values (look for the prefix <CODE>A_</CODE>).<P> + +There are two ways to make highlights. One is to logical-or the value of the +highlights you want into the character argument of an <CODE>addch()</CODE> call, +or any other output call that takes a <CODE>chtype</CODE> argument. <P> + +The other is to set the current-highlight value. This is logical-or'ed with +any highlight you specify the first way. You do this with the functions +<CODE>attron()</CODE>, <CODE>attroff()</CODE>, and <CODE>attrset()</CODE>; see the manual +pages for details. + +Color is a special kind of highlight. The package actually thinks in terms +of color pairs, combinations of foreground and background colors. The sample +code above sets up eight color pairs, all of the guaranteed-available colors +on black. Note that each color pair is, in effect, given the name of its +foreground color. Any other range of eight non-conflicting values could +have been used as the first arguments of the <CODE>init_pair()</CODE> values. <P> + +Once you've done an <CODE>init_pair()</CODE> that creates color-pair N, you can +use <CODE>COLOR_PAIR(N)</CODE> as a highlight that invokes that particular +color combination. Note that <CODE>COLOR_PAIR(N)</CODE>, for constant N, +is itself a compile-time constant and can be used in initializers. + +<H3><A NAME="mouse">Mouse Interfacing</A></H3> + +The <CODE>ncurses</CODE> library also provides a mouse interface. +<!-- The 'note' tag is not portable enough --> +<blockquote> +<strong>NOTE:</strong> this facility is specific to <CODE>ncurses</CODE>, it is not part of either +the XSI Curses standard, nor of System V Release 4, nor BSD curses. +System V Release 4 curses contains code with similar interface definitions, +however it is not documented. Other than by disassembling the library, we +have no way to determine exactly how that mouse code works. +Thus, we recommend that you wrap mouse-related code in an #ifdef using the +feature macro NCURSES_MOUSE_VERSION so it will not be compiled and linked +on non-ncurses systems. +</blockquote> + +Presently, mouse event reporting works in the following environments: +<ul> +<li>xterm and similar programs such as rxvt. +<li>Linux console, when configured with <CODE>gpm</CODE>(1), Alessandro +Rubini's mouse server. +<li>FreeBSD sysmouse (console) +<li>OS/2 EMX +</ul> +<P> +The mouse interface is very simple. To activate it, you use the function +<CODE>mousemask()</CODE>, passing it as first argument a bit-mask that specifies +what kinds of events you want your program to be able to see. It will +return the bit-mask of events that actually become visible, which may differ +from the argument if the mouse device is not capable of reporting some of +the event types you specify. <P> + +Once the mouse is active, your application's command loop should watch +for a return value of <CODE>KEY_MOUSE</CODE> from <CODE>wgetch()</CODE>. When +you see this, a mouse event report has been queued. To pick it off +the queue, use the function <CODE>getmouse()</CODE> (you must do this before +the next <CODE>wgetch()</CODE>, otherwise another mouse event might come +in and make the first one inaccessible). <P> + +Each call to <CODE>getmouse()</CODE> fills a structure (the address of which you'll +pass it) with mouse event data. The event data includes zero-origin, +screen-relative character-cell coordinates of the mouse pointer. It also +includes an event mask. Bits in this mask will be set, corresponding +to the event type being reported. <P> + +The mouse structure contains two additional fields which may be +significant in the future as ncurses interfaces to new kinds of +pointing device. In addition to x and y coordinates, there is a slot +for a z coordinate; this might be useful with touch-screens that can +return a pressure or duration parameter. There is also a device ID +field, which could be used to distinguish between multiple pointing +devices. <P> + +The class of visible events may be changed at any time via <CODE>mousemask()</CODE>. +Events that can be reported include presses, releases, single-, double- and +triple-clicks (you can set the maximum button-down time for clicks). If +you don't make clicks visible, they will be reported as press-release +pairs. In some environments, the event mask may include bits reporting +the state of shift, alt, and ctrl keys on the keyboard during the event. <P> + +A function to check whether a mouse event fell within a given window is +also supplied. You can use this to see whether a given window should +consider a mouse event relevant to it. <P> + +Because mouse event reporting will not be available in all +environments, it would be unwise to build <CODE>ncurses</CODE> +applications that <EM>require</EM> the use of a mouse. Rather, you should +use the mouse as a shortcut for point-and-shoot commands your application +would normally accept from the keyboard. Two of the test games in the +<CODE>ncurses</CODE> distribution (<CODE>bs</CODE> and <CODE>knight</CODE>) contain +code that illustrates how this can be done. <P> + +See the manual page <CODE>curs_mouse(3X)</CODE> for full details of the +mouse-interface functions. + +<H3><A NAME="finishing">Finishing Up</A></H3> + +In order to clean up after the <CODE>ncurses</CODE> routines, the routine +<CODE>endwin()</CODE> is provided. It restores tty modes to what they were when +<CODE>initscr()</CODE> was first called, and moves the cursor down to the +lower-left corner. Thus, anytime after the call to initscr, <CODE>endwin()</CODE> +should be called before exiting. + +<H2><A NAME="functions">Function Descriptions</A></H2> + +We describe the detailed behavior of some important curses functions here, as a +supplement to the manual page descriptions. + +<H3><A NAME="init">Initialization and Wrapup</A></H3> + +<DL> +<DT> <CODE>initscr()</CODE> +<DD> The first function called should almost always be <CODE>initscr()</CODE>. +This will determine the terminal type and +initialize curses data structures. <CODE>initscr()</CODE> also arranges that +the first call to <CODE>refresh()</CODE> will clear the screen. If an error +occurs a message is written to standard error and the program +exits. Otherwise it returns a pointer to stdscr. A few functions may be +called before initscr (<CODE>slk_init()</CODE>, <CODE>filter()</CODE>, +<CODE>ripoffline()</CODE>, <CODE>use_env()</CODE>, and, if you are using multiple +terminals, <CODE>newterm()</CODE>.) +<DT> <CODE>endwin()</CODE> +<DD> Your program should always call <CODE>endwin()</CODE> before exiting or +shelling out of the program. This function will restore tty modes, +move the cursor to the lower left corner of the screen, reset the +terminal into the proper non-visual mode. Calling <CODE>refresh()</CODE> +or <CODE>doupdate()</CODE> after a temporary escape from the program will +restore the ncurses screen from before the escape. +<DT> <CODE>newterm(type, ofp, ifp)</CODE> +<DD> A program which outputs to more than one terminal should use +<CODE>newterm()</CODE> instead of <CODE>initscr()</CODE>. <CODE>newterm()</CODE> should +be called once for each terminal. It returns a variable of type +<CODE>SCREEN *</CODE> which should be saved as a reference to that +terminal. +(NOTE: a SCREEN variable is not a <em>screen</em> in the sense we +are describing in this introduction, but a collection of +parameters used to assist in optimizing the display.) +The arguments are the type of the terminal (a string) and +<CODE>FILE</CODE> pointers for the output and input of the terminal. If +type is NULL then the environment variable <CODE>$TERM</CODE> is used. +<CODE>endwin()</CODE> should called once at wrapup time for each terminal +opened using this function. +<DT> <CODE>set_term(new)</CODE> +<DD> This function is used to switch to a different terminal previously +opened by <CODE>newterm()</CODE>. The screen reference for the new terminal +is passed as the parameter. The previous terminal is returned by the +function. All other calls affect only the current terminal. +<DT> <CODE>delscreen(sp)</CODE> +<DD> The inverse of <CODE>newterm()</CODE>; deallocates the data structures +associated with a given <CODE>SCREEN</CODE> reference. +</DL> + +<H3><A NAME="flush">Causing Output to the Terminal</A></H3> + +<DL> +<DT> <CODE>refresh()</CODE> and <CODE>wrefresh(win)</CODE> +<DD> These functions must be called to actually get any output on +the terminal, as other routines merely manipulate data +structures. <CODE>wrefresh()</CODE> copies the named window to the physical +terminal screen, taking into account what is already +there in order to do optimizations. <CODE>refresh()</CODE> does a +refresh of <CODE>stdscr</CODE>. Unless <CODE>leaveok()</CODE> has been +enabled, the physical cursor of the terminal is left at the +location of the window's cursor. +<DT> <CODE>doupdate()</CODE> and <CODE>wnoutrefresh(win)</CODE> +<DD> These two functions allow multiple updates with more efficiency +than wrefresh. To use them, it is important to understand how curses +works. In addition to all the window structures, curses keeps two +data structures representing the terminal screen: a physical screen, +describing what is actually on the screen, and a virtual screen, +describing what the programmer wants to have on the screen. wrefresh +works by first copying the named window to the virtual screen +(<CODE>wnoutrefresh()</CODE>), and then calling the routine to update the +screen (<CODE>doupdate()</CODE>). If the programmer wishes to output +several windows at once, a series of calls to <CODE>wrefresh</CODE> will result +in alternating calls to <CODE>wnoutrefresh()</CODE> and <CODE>doupdate()</CODE>, +causing several bursts of output to the screen. By calling +<CODE>wnoutrefresh()</CODE> for each window, it is then possible to call +<CODE>doupdate()</CODE> once, resulting in only one burst of output, with +fewer total characters transmitted (this also avoids a visually annoying +flicker at each update). +</DL> + +<H3><A NAME="lowlevel">Low-Level Capability Access</A></H3> + +<DL> +<DT> <CODE>setupterm(term, filenum, errret)</CODE> +<DD> This routine is called to initialize a terminal's description, without setting +up the curses screen structures or changing the tty-driver mode bits. +<CODE>term</CODE> is the character string representing the name of the terminal +being used. <CODE>filenum</CODE> is the UNIX file descriptor of the terminal to +be used for output. <CODE>errret</CODE> is a pointer to an integer, in which a +success or failure indication is returned. The values returned can be 1 (all +is well), 0 (no such terminal), or -1 (some problem locating the terminfo +database). <P> + +The value of <CODE>term</CODE> can be given as NULL, which will cause the value of +<CODE>TERM</CODE> in the environment to be used. The <CODE>errret</CODE> pointer can +also be given as NULL, meaning no error code is wanted. If <CODE>errret</CODE> is +defaulted, and something goes wrong, <CODE>setupterm()</CODE> will print an +appropriate error message and exit, rather than returning. Thus, a simple +program can call setupterm(0, 1, 0) and not worry about initialization +errors. <P> + +After the call to <CODE>setupterm()</CODE>, the global variable <CODE>cur_term</CODE> is +set to point to the current structure of terminal capabilities. By calling +<CODE>setupterm()</CODE> for each terminal, and saving and restoring +<CODE>cur_term</CODE>, it is possible for a program to use two or more terminals at +once. <CODE>Setupterm()</CODE> also stores the names section of the terminal +description in the global character array <CODE>ttytype[]</CODE>. Subsequent calls +to <CODE>setupterm()</CODE> will overwrite this array, so you'll have to save it +yourself if need be. +</DL> + +<H3><A NAME="debugging">Debugging</A></H3> + +<!-- The 'note' tag is not portable enough --> +<blockquote> +<strong>NOTE:</strong> These functions are not part of the standard curses API! +</blockquote> + +<DL> +<DT> <CODE>trace()</CODE> +<DD> +This function can be used to explicitly set a trace level. If the +trace level is nonzero, execution of your program will generate a file +called `trace' in the current working directory containing a report on +the library's actions. Higher trace levels enable more detailed (and +verbose) reporting -- see comments attached to <CODE>TRACE_</CODE> defines +in the <CODE>curses.h</CODE> file for details. (It is also possible to set +a trace level by assigning a trace level value to the environment variable +<CODE>NCURSES_TRACE</CODE>). +<DT> <CODE>_tracef()</CODE> +<DD> +This function can be used to output your own debugging information. It is only +available only if you link with -lncurses_g. It can be used the same way as +<CODE>printf()</CODE>, only it outputs a newline after the end of arguments. +The output goes to a file called <CODE>trace</CODE> in the current directory. +</DL> + +Trace logs can be difficult to interpret due to the sheer volume of +data dumped in them. There is a script called <STRONG>tracemunch</STRONG> +included with the <CODE>ncurses</CODE> distribution that can alleviate +this problem somewhat; it compacts long sequences of similar operations into +more succinct single-line pseudo-operations. These pseudo-ops can be +distinguished by the fact that they are named in capital letters. + +<H2><A NAME="hints">Hints, Tips, and Tricks</A></H2> + +The <CODE>ncurses</CODE> manual pages are a complete reference for this library. +In the remainder of this document, we discuss various useful methods that +may not be obvious from the manual page descriptions. + +<H3><A NAME="caution">Some Notes of Caution</A></H3> + +If you find yourself thinking you need to use <CODE>noraw()</CODE> or +<CODE>nocbreak()</CODE>, think again and move carefully. It's probably +better design to use <CODE>getstr()</CODE> or one of its relatives to +simulate cooked mode. The <CODE>noraw()</CODE> and <CODE>nocbreak()</CODE> +functions try to restore cooked mode, but they may end up clobbering +some control bits set before you started your application. Also, they +have always been poorly documented, and are likely to hurt your +application's usability with other curses libraries. <P> + +Bear in mind that <CODE>refresh()</CODE> is a synonym for <CODE>wrefresh(stdscr)</CODE>. +Don't try to mix use of <CODE>stdscr</CODE> with use of windows declared +by <CODE>newwin()</CODE>; a <CODE>refresh()</CODE> call will blow them off the +screen. The right way to handle this is to use <CODE>subwin()</CODE>, or +not touch <CODE>stdscr</CODE> at all and tile your screen with declared +windows which you then <CODE>wnoutrefresh()</CODE> somewhere in your program +event loop, with a single <CODE>doupdate()</CODE> call to trigger actual +repainting. <P> + +You are much less likely to run into problems if you design your screen +layouts to use tiled rather than overlapping windows. Historically, +curses support for overlapping windows has been weak, fragile, and poorly +documented. The <CODE>ncurses</CODE> library is not yet an exception to this +rule. <P> + +There is a panels library included in the <CODE>ncurses</CODE> +distribution that does a pretty good job of strengthening the +overlapping-windows facilities. <P> + +Try to avoid using the global variables LINES and COLS. Use +<CODE>getmaxyx()</CODE> on the <CODE>stdscr</CODE> context instead. Reason: +your code may be ported to run in an environment with window resizes, +in which case several screens could be open with different sizes. + +<H3><A NAME="leaving">Temporarily Leaving NCURSES Mode</A></H3> + +Sometimes you will want to write a program that spends most of its time in +screen mode, but occasionally returns to ordinary `cooked' mode. A common +reason for this is to support shell-out. This behavior is simple to arrange +in <CODE>ncurses</CODE>. <P> + +To leave <CODE>ncurses</CODE> mode, call <CODE>endwin()</CODE> as you would if you +were intending to terminate the program. This will take the screen back to +cooked mode; you can do your shell-out. When you want to return to +<CODE>ncurses</CODE> mode, simply call <CODE>refresh()</CODE> or <CODE>doupdate()</CODE>. +This will repaint the screen. <P> + +There is a boolean function, <CODE>isendwin()</CODE>, which code can use to +test whether <CODE>ncurses</CODE> screen mode is active. It returns <CODE>TRUE</CODE> +in the interval between an <CODE>endwin()</CODE> call and the following +<CODE>refresh()</CODE>, <CODE>FALSE</CODE> otherwise. <P> + +Here is some sample code for shellout: + +<PRE> + addstr("Shelling out..."); + def_prog_mode(); /* save current tty modes */ + endwin(); /* restore original tty modes */ + system("sh"); /* run shell */ + addstr("returned.\n"); /* prepare return message */ + refresh(); /* restore save modes, repaint screen */ +</PRE> + +<H3><A NAME="xterm">Using NCURSES under XTERM</A></H3> + +A resize operation in X sends <CODE>SIGWINCH</CODE> to the application running +under xterm. + +The easiest way to handle <CODE>SIGWINCH</CODE> +is to do an <CODE>endwin</CODE>, +followed by an <CODE>refresh</CODE> and a screen repaint you code +yourself. +The <CODE>refresh</CODE> will pick up the new screen size from the +xterm's environment. <P> + +That is the standard way, of course (it even works with some vendor's curses +implementations). +Its drawback is that it clears the screen to reinitialize the display, and does +not resize subwindows which must be shrunk. +<CODE>Ncurses</CODE> provides an extension which works better, the +<CODE>resizeterm</CODE> function. That function ensures that all windows +are limited to the new screen dimensions, and pads <CODE>stdscr</CODE> +with blanks if the screen is larger. <P> + +The <CODE>ncurses</CODE> library provides a SIGWINCH signal handler, +which pushes a <CODE>KEY_RESIZE</CODE> via the wgetch() calls. +When <CODE>ncurses</CODE> returns that code, +it calls <code>resizeterm</CODE> +to update the size of the standard screen's window, repainting that +(filling with blanks or truncating as needed). +It also resizes other windows, +but its effect may be less satisfactory because it cannot +know how you want the screen re-painted. +You will usually have to write special-purpose code to handle +<CODE>KEY_RESIZE</CODE> yourself. + +<H3><A NAME="screens">Handling Multiple Terminal Screens</A></H3> + +The <CODE>initscr()</CODE> function actually calls a function named +<CODE>newterm()</CODE> to do most of its work. If you are writing a program that +opens multiple terminals, use <CODE>newterm()</CODE> directly. <P> + +For each call, you will have to specify a terminal type and a pair of file +pointers; each call will return a screen reference, and <CODE>stdscr</CODE> will be +set to the last one allocated. You will switch between screens with the +<CODE>set_term</CODE> call. Note that you will also have to call +<CODE>def_shell_mode</CODE> and <CODE>def_prog_mode</CODE> on each tty yourself. + +<H3><A NAME="testing">Testing for Terminal Capabilities</A></H3> + +Sometimes you may want to write programs that test for the presence of various +capabilities before deciding whether to go into <CODE>ncurses</CODE> mode. An easy +way to do this is to call <CODE>setupterm()</CODE>, then use the functions +<CODE>tigetflag()</CODE>, <CODE>tigetnum()</CODE>, and <CODE>tigetstr()</CODE> to do your +testing. <P> + +A particularly useful case of this often comes up when you want to +test whether a given terminal type should be treated as `smart' +(cursor-addressable) or `stupid'. The right way to test this is to see +if the return value of <CODE>tigetstr("cup")</CODE> is non-NULL. Alternatively, +you can include the <CODE>term.h</CODE> file and test the value of the +macro <CODE>cursor_address</CODE>. + +<H3><A NAME="tuning">Tuning for Speed</A></H3> + +Use the <CODE>addchstr()</CODE> family of functions for fast +screen-painting of text when you know the text doesn't contain any +control characters. Try to make attribute changes infrequent on your +screens. Don't use the <CODE>immedok()</CODE> option! + +<H3><A NAME="special">Special Features of NCURSES</A></H3> + +The <CODE>wresize()</CODE> function allows you to resize a window in place. +The associated <CODE>resizeterm()</CODE> function simplifies the construction +of <a HREF="#xterm">SIGWINCH</a> handlers, for resizing all windows. <P> + +The <CODE>define_key()</CODE> function allows you +to define at runtime function-key control sequences which are not in the +terminal description. +The <CODE>keyok()</CODE> function allows you to temporarily +enable or disable interpretation of any function-key control sequence. <P> + +The <CODE>use_default_colors()</CODE> function allows you to construct +applications which can use the terminal's default foreground and +background colors as an additional "default" color. +Several terminal emulators support this feature, which is based on ISO 6429. <P> + +Ncurses supports up 16 colors, unlike SVr4 curses which defines only 8. +While most terminals which provide color allow only 8 colors, about +a quarter (including XFree86 xterm) support 16 colors. + +<H2><A NAME="compat">Compatibility with Older Versions</A></H2> + +Despite our best efforts, there are some differences between <CODE>ncurses</CODE> +and the (undocumented!) behavior of older curses implementations. These arise +from ambiguities or omissions in the documentation of the API. + +<H3><A NAME="refbug">Refresh of Overlapping Windows</A></H3> + +If you define two windows A and B that overlap, and then alternately scribble +on and refresh them, the changes made to the overlapping region under historic +<CODE>curses</CODE> versions were often not documented precisely. <P> + +To understand why this is a problem, remember that screen updates are +calculated between two representations of the <EM>entire</EM> display. The +documentation says that when you refresh a window, it is first copied to the +virtual screen, and then changes are calculated to update the physical screen +(and applied to the terminal). But "copied to" is not very specific, and +subtle differences in how copying works can produce different behaviors in the +case where two overlapping windows are each being refreshed at unpredictable +intervals. <P> + +What happens to the overlapping region depends on what <CODE>wnoutrefresh()</CODE> +does with its argument -- what portions of the argument window it copies to the +virtual screen. Some implementations do "change copy", copying down only +locations in the window that have changed (or been marked changed with +<CODE>wtouchln()</CODE> and friends). Some implementations do "entire copy", +copying <EM>all</EM> window locations to the virtual screen whether or not +they have changed. <P> + +The <CODE>ncurses</CODE> library itself has not always been consistent on this +score. Due to a bug, versions 1.8.7 to 1.9.8a did entire copy. Versions +1.8.6 and older, and versions 1.9.9 and newer, do change copy. <P> + +For most commercial curses implementations, it is not documented and not known +for sure (at least not to the <CODE>ncurses</CODE> maintainers) whether they do +change copy or entire copy. We know that System V release 3 curses has logic +in it that looks like an attempt to do change copy, but the surrounding logic +and data representations are sufficiently complex, and our knowledge +sufficiently indirect, that it's hard to know whether this is reliable. + +It is not clear what the SVr4 documentation and XSI standard intend. The XSI +Curses standard barely mentions wnoutrefresh(); the SVr4 documents seem to be +describing entire-copy, but it is possible with some effort and straining to +read them the other way. <P> + +It might therefore be unwise to rely on either behavior in programs that might +have to be linked with other curses implementations. Instead, you can do an +explicit <CODE>touchwin()</CODE> before the <CODE>wnoutrefresh()</CODE> call to +guarantee an entire-contents copy anywhere. <P> + +The really clean way to handle this is to use the panels library. If, +when you want a screen update, you do <CODE>update_panels()</CODE>, it will +do all the necessary <CODE>wnoutrefresh()</CODE> calls for whatever panel +stacking order you have defined. Then you can do one <CODE>doupdate()</CODE> +and there will be a <EM>single</EM> burst of physical I/O that will do +all your updates. + +<H3><A NAME="backbug">Background Erase</A></H3> + +If you have been using a very old versions of <CODE>ncurses</CODE> (1.8.7 or +older) you may be surprised by the behavior of the erase functions. In older +versions, erased areas of a window were filled with a blank modified by the +window's current attribute (as set by <STRONG>wattrset()</STRONG>, <STRONG>wattron()</STRONG>, +<STRONG>wattroff()</STRONG> and friends). <P> + +In newer versions, this is not so. Instead, the attribute of erased blanks +is normal unless and until it is modified by the functions <CODE>bkgdset()</CODE> +or <CODE>wbkgdset()</CODE>. <P> + +This change in behavior conforms <CODE>ncurses</CODE> to System V Release 4 and +the XSI Curses standard. + +<H2><A NAME="xsifuncs">XSI Curses Conformance</A></H2> + +The <CODE>ncurses</CODE> library is intended to be base-level conformant with the +XSI Curses standard from X/Open. Many extended-level features (in fact, almost +all features not directly concerned with wide characters and +internationalization) are also supported. <P> + +One effect of XSI conformance is the change in behavior described under +<A HREF="#backbug">"Background Erase -- Compatibility with Old Versions"</A>. <P> + +Also, <CODE>ncurses</CODE> meets the XSI requirement that every macro +entry point have a corresponding function which may be linked (and +will be prototype-checked) if the macro definition is disabled with +<CODE>#undef</CODE>. + +<H1><A NAME="panels">The Panels Library</A></H1> + +The <CODE>ncurses</CODE> library by itself provides good support for screen +displays in which the windows are tiled (non-overlapping). In the more +general case that windows may overlap, you have to use a series of +<CODE>wnoutrefresh()</CODE> calls followed by a <CODE>doupdate()</CODE>, and be +careful about the order you do the window refreshes in. It has to be +bottom-upwards, otherwise parts of windows that should be obscured will +show through. <P> + +When your interface design is such that windows may dive deeper into the +visibility stack or pop to the top at runtime, the resulting book-keeping +can be tedious and difficult to get right. Hence the panels library. <P> + +The <CODE>panel</CODE> library first appeared in AT&T System V. The +version documented here is the <CODE>panel</CODE> code distributed +with <CODE>ncurses</CODE>. + +<H2><A NAME="pcompile">Compiling With the Panels Library</A></H2> + +Your panels-using modules must import the panels library declarations with + +<PRE> + #include <panel.h> +</PRE> + +and must be linked explicitly with the panels library using an +<CODE>-lpanel</CODE> argument. Note that they must also link the +<CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers +are two-pass and will accept either order, but it is still good practice +to put <CODE>-lpanel</CODE> first and <CODE>-lncurses</CODE> second. + +<H2><A NAME="poverview">Overview of Panels</A></H2> + +A panel object is a window that is implicitly treated as part of a +<DFN>deck</DFN> including all other panel objects. The deck has an implicit +bottom-to-top visibility order. The panels library includes an update +function (analogous to <CODE>refresh()</CODE>) that displays all panels in the +deck in the proper order to resolve overlaps. The standard window, +<CODE>stdscr</CODE>, is considered below all panels. <P> + +Details on the panels functions are available in the man pages. We'll just +hit the highlights here. <P> + +You create a panel from a window by calling <CODE>new_panel()</CODE> on a +window pointer. It then becomes the top of the deck. The panel's window +is available as the value of <CODE>panel_window()</CODE> called with the +panel pointer as argument.<P> + +You can delete a panel (removing it from the deck) with <CODE>del_panel</CODE>. +This will not deallocate the associated window; you have to do that yourself. + +You can replace a panel's window with a different window by calling +<CODE>replace_window</CODE>. The new window may be of different size; +the panel code will re-compute all overlaps. This operation doesn't +change the panel's position in the deck. <P> + +To move a panel's window, use <CODE>move_panel()</CODE>. The +<CODE>mvwin()</CODE> function on the panel's window isn't sufficient because it +doesn't update the panels library's representation of where the windows are. +This operation leaves the panel's depth, contents, and size unchanged. <P> + +Two functions (<CODE>top_panel()</CODE>, <CODE>bottom_panel()</CODE>) are +provided for rearranging the deck. The first pops its argument window to the +top of the deck; the second sends it to the bottom. Either operation leaves +the panel's screen location, contents, and size unchanged. <P> + +The function <CODE>update_panels()</CODE> does all the +<CODE>wnoutrefresh()</CODE> calls needed to prepare for +<CODE>doupdate()</CODE> (which you must call yourself, afterwards). <P> + +Typically, you will want to call <CODE>update_panels()</CODE> and +<CODE>doupdate()</CODE> just before accepting command input, once in each cycle +of interaction with the user. If you call <CODE>update_panels()</CODE> after +each and every panel write, you'll generate a lot of unnecessary refresh +activity and screen flicker. + +<H2><A NAME="pstdscr">Panels, Input, and the Standard Screen</A></H2> + +You shouldn't mix <CODE>wnoutrefresh()</CODE> or <CODE>wrefresh()</CODE> +operations with panels code; this will work only if the argument window +is either in the top panel or unobscured by any other panels. <P> + +The <CODE>stsdcr</CODE> window is a special case. It is considered below all +panels. Because changes to panels may obscure parts of <CODE>stdscr</CODE>, +though, you should call <CODE>update_panels()</CODE> before +<CODE>doupdate()</CODE> even when you only change <CODE>stdscr</CODE>. <P> + +Note that <CODE>wgetch</CODE> automatically calls <CODE>wrefresh</CODE>. +Therefore, before requesting input from a panel window, you need to be sure +that the panel is totally unobscured. <P> + +There is presently no way to display changes to one obscured panel without +repainting all panels. + +<H2><A NAME="hiding">Hiding Panels</A></H2> + +It's possible to remove a panel from the deck temporarily; use +<CODE>hide_panel</CODE> for this. Use <CODE>show_panel()</CODE> to render it +visible again. The predicate function <CODE>panel_hidden</CODE> +tests whether or not a panel is hidden. <P> + +The <CODE>panel_update</CODE> code ignores hidden panels. You cannot do +<CODE>top_panel()</CODE> or <CODE>bottom_panel</CODE> on a hidden panel(). +Other panels operations are applicable. + +<H2><A NAME="pmisc">Miscellaneous Other Facilities</A></H2> + +It's possible to navigate the deck using the functions +<CODE>panel_above()</CODE> and <CODE>panel_below</CODE>. Handed a panel +pointer, they return the panel above or below that panel. Handed +<CODE>NULL</CODE>, they return the bottom-most or top-most panel. <P> + +Every panel has an associated user pointer, not used by the panel code, to +which you can attach application data. See the man page documentation +of <CODE>set_panel_userptr()</CODE> and <CODE>panel_userptr</CODE> for +details. + +<H1><A NAME="menu">The Menu Library</A></H1> + +A menu is a screen display that assists the user to choose some subset +of a given set of items. The <CODE>menu</CODE> library is a curses +extension that supports easy programming of menu hierarchies with a +uniform but flexible interface. <P> + +The <CODE>menu</CODE> library first appeared in AT&T System V. The +version documented here is the <CODE>menu</CODE> code distributed +with <CODE>ncurses</CODE>. + +<H2><A NAME="mcompile">Compiling With the menu Library</A></H2> + +Your menu-using modules must import the menu library declarations with + +<PRE> + #include <menu.h> +</PRE> + +and must be linked explicitly with the menus library using an +<CODE>-lmenu</CODE> argument. Note that they must also link the +<CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers +are two-pass and will accept either order, but it is still good practice +to put <CODE>-lmenu</CODE> first and <CODE>-lncurses</CODE> second. + +<H2><A NAME="moverview">Overview of Menus</A></H2> + +The menus created by this library consist of collections of +<DFN>items</DFN> including a name string part and a description string +part. To make menus, you create groups of these items and connect +them with menu frame objects. <P> + +The menu can then by <DFN>posted</DFN>, that is written to an +associated window. Actually, each menu has two associated windows; a +containing window in which the programmer can scribble titles or +borders, and a subwindow in which the menu items proper are displayed. +If this subwindow is too small to display all the items, it will be a +scrollable viewport on the collection of items. <P> + +A menu may also be <DFN>unposted</DFN> (that is, undisplayed), and finally +freed to make the storage associated with it and its items available for +re-use. <P> + +The general flow of control of a menu program looks like this: + +<OL> +<LI>Initialize <CODE>curses</CODE>. +<LI>Create the menu items, using <CODE>new_item()</CODE>. +<LI>Create the menu using <CODE>new_menu()</CODE>. +<LI>Post the menu using <CODE>post_menu()</CODE>. +<LI>Refresh the screen. +<LI>Process user requests via an input loop. +<LI>Unpost the menu using <CODE>unpost_menu()</CODE>. +<LI>Free the menu, using <CODE>free_menu()</CODE>. +<LI>Free the items using <CODE>free_item()</CODE>. +<LI>Terminate <CODE>curses</CODE>. +</OL> + +<H2><A NAME="mselect">Selecting items</A></H2> + +Menus may be multi-valued or (the default) single-valued (see the manual +page <CODE>menu_opts(3x)</CODE> to see how to change the default). +Both types always have a <DFN>current item</DFN>. <P> + +From a single-valued menu you can read the selected value simply by looking +at the current item. From a multi-valued menu, you get the selected set +by looping through the items applying the <CODE>item_value()</CODE> +predicate function. Your menu-processing code can use the function +<CODE>set_item_value()</CODE> to flag the items in the select set. <P> + +Menu items can be made unselectable using <CODE>set_item_opts()</CODE> +or <CODE>item_opts_off()</CODE> with the <CODE>O_SELECTABLE</CODE> +argument. This is the only option so far defined for menus, but it +is good practice to code as though other option bits might be on. + +<H2><A NAME="mdisplay">Menu Display</A></H2> + +The menu library calculates a minimum display size for your window, based +on the following variables: + +<UL> +<LI>The number and maximum length of the menu items +<LI>Whether the O_ROWMAJOR option is enabled +<LI>Whether display of descriptions is enabled +<LI>Whatever menu format may have been set by the programmer +<LI>The length of the menu mark string used for highlighting selected items +</UL> + +The function <CODE>set_menu_format()</CODE> allows you to set the +maximum size of the viewport or <DFN>menu page</DFN> that will be used +to display menu items. You can retrieve any format associated with a +menu with <CODE>menu_format()</CODE>. The default format is rows=16, +columns=1. <P> + +The actual menu page may be smaller than the format size. This depends +on the item number and size and whether O_ROWMAJOR is on. This option +(on by default) causes menu items to be displayed in a `raster-scan' +pattern, so that if more than one item will fit horizontally the first +couple of items are side-by-side in the top row. The alternative is +column-major display, which tries to put the first several items in +the first column. <P> + +As mentioned above, a menu format not large enough to allow all items to fit +on-screen will result in a menu display that is vertically scrollable. <P> +You can scroll it with requests to the menu driver, which will be described +in the section on <A HREF="#minput">menu input handling</A>. <P> + +Each menu has a <DFN>mark string</DFN> used to visually tag selected items; +see the <CODE>menu_mark(3x)</CODE> manual page for details. The mark +string length also influences the menu page size. <P> + +The function <CODE>scale_menu()</CODE> returns the minimum display size +that the menu code computes from all these factors. + +There are other menu display attributes including a select attribute, +an attribute for selectable items, an attribute for unselectable items, +and a pad character used to separate item name text from description +text. These have reasonable defaults which the library allows you to +change (see the <CODE>menu_attribs(3x)</CODE> manual page. + +<H2><A NAME="mwindows">Menu Windows</A></H2> + +Each menu has, as mentioned previously, a pair of associated windows. +Both these windows are painted when the menu is posted and erased when +the menu is unposted. <P> + +The outer or frame window is not otherwise touched by the menu +routines. It exists so the programmer can associate a title, a +border, or perhaps help text with the menu and have it properly +refreshed or erased at post/unpost time. The inner window or +<DFN>subwindow</DFN> is where the current menu page is displayed. <P> + +By default, both windows are <CODE>stdscr</CODE>. You can set them with the +functions in <CODE>menu_win(3x)</CODE>. <P> + +When you call <CODE>post_menu()</CODE>, you write the menu to its +subwindow. When you call <CODE>unpost_menu()</CODE>, you erase the +subwindow, However, neither of these actually modifies the screen. To +do that, call <CODE>wrefresh()</CODE> or some equivalent. + +<H2><A NAME="minput">Processing Menu Input</A></H2> + +The main loop of your menu-processing code should call +<CODE>menu_driver()</CODE> repeatedly. The first argument of this routine +is a menu pointer; the second is a menu command code. You should write an +input-fetching routine that maps input characters to menu command codes, and +pass its output to <CODE>menu_driver()</CODE>. The menu command codes are +fully documented in <CODE>menu_driver(3x)</CODE>. <P> + +The simplest group of command codes is <CODE>REQ_NEXT_ITEM</CODE>, +<CODE>REQ_PREV_ITEM</CODE>, <CODE>REQ_FIRST_ITEM</CODE>, +<CODE>REQ_LAST_ITEM</CODE>, <CODE>REQ_UP_ITEM</CODE>, +<CODE>REQ_DOWN_ITEM</CODE>, <CODE>REQ_LEFT_ITEM</CODE>, +<CODE>REQ_RIGHT_ITEM</CODE>. These change the currently selected +item. These requests may cause scrolling of the menu page if it only +partially displayed. <P> + +There are explicit requests for scrolling which also change the +current item (because the select location does not change, but the +item there does). These are <CODE>REQ_SCR_DLINE</CODE>, +<CODE>REQ_SCR_ULINE</CODE>, <CODE>REQ_SCR_DPAGE</CODE>, and +<CODE>REQ_SCR_UPAGE</CODE>. <P> + +The <CODE>REQ_TOGGLE_ITEM</CODE> selects or deselects the current item. +It is for use in multi-valued menus; if you use it with <CODE>O_ONEVALUE</CODE> +on, you'll get an error return (<CODE>E_REQUEST_DENIED</CODE>). <P> + +Each menu has an associated pattern buffer. The +<CODE>menu_driver()</CODE> logic tries to accumulate printable ASCII +characters passed in in that buffer; when it matches a prefix of an +item name, that item (or the next matching item) is selected. If +appending a character yields no new match, that character is deleted +from the pattern buffer, and <CODE>menu_driver()</CODE> returns +<CODE>E_NO_MATCH</CODE>. <P> + +Some requests change the pattern buffer directly: +<CODE>REQ_CLEAR_PATTERN</CODE>, <CODE>REQ_BACK_PATTERN</CODE>, +<CODE>REQ_NEXT_MATCH</CODE>, <CODE>REQ_PREV_MATCH</CODE>. The latter +two are useful when pattern buffer input matches more than one item +in a multi-valued menu. <P> + +Each successful scroll or item navigation request clears the pattern +buffer. It is also possible to set the pattern buffer explicitly +with <CODE>set_menu_pattern()</CODE>. <P> + +Finally, menu driver requests above the constant <CODE>MAX_COMMAND</CODE> +are considered application-specific commands. The <CODE>menu_driver()</CODE> +code ignores them and returns <CODE>E_UNKNOWN_COMMAND</CODE>. + +<H2><A NAME="mmisc">Miscellaneous Other Features</A></H2> + +Various menu options can affect the processing and visual appearance +and input processing of menus. See <CODE>menu_opts(3x) for +details.</CODE> <P> + +It is possible to change the current item from application code; this +is useful if you want to write your own navigation requests. It is +also possible to explicitly set the top row of the menu display. See +<CODE>mitem_current(3x)</CODE>. + +If your application needs to change the menu subwindow cursor for +any reason, <CODE>pos_menu_cursor()</CODE> will restore it to the +correct location for continuing menu driver processing. <P> + +It is possible to set hooks to be called at menu initialization and +wrapup time, and whenever the selected item changes. See +<CODE>menu_hook(3x)</CODE>. <P> + +Each item, and each menu, has an associated user pointer on which you +can hang application data. See <CODE>mitem_userptr(3x)</CODE> and +<CODE>menu_userptr(3x)</CODE>. + +<H1><A NAME="form">The Forms Library</A></H1> + +The <CODE>form</CODE> library is a curses extension that supports easy +programming of on-screen forms for data entry and program control. <P> + +The <CODE>form</CODE> library first appeared in AT&T System V. The +version documented here is the <CODE>form</CODE> code distributed +with <CODE>ncurses</CODE>. + +<H2><A NAME="fcompile">Compiling With the form Library</A></H2> + +Your form-using modules must import the form library declarations with + +<PRE> + #include <form.h> +</PRE> + +and must be linked explicitly with the forms library using an +<CODE>-lform</CODE> argument. Note that they must also link the +<CODE>ncurses</CODE> library with <CODE>-lncurses</CODE>. Many linkers +are two-pass and will accept either order, but it is still good practice +to put <CODE>-lform</CODE> first and <CODE>-lncurses</CODE> second. + +<H2><A NAME="foverview">Overview of Forms</A></H2> + +A form is a collection of fields; each field may be either a label +(explanatory text) or a data-entry location. Long forms may be +segmented into pages; each entry to a new page clears the screen. <P> +To make forms, you create groups of fields and connect them with form +frame objects; the form library makes this relatively simple. <P> + +Once defined, a form can be <DFN>posted</DFN>, that is written to an +associated window. Actually, each form has two associated windows; a +containing window in which the programmer can scribble titles or +borders, and a subwindow in which the form fields proper are displayed. <P> + +As the form user fills out the posted form, navigation and editing +keys support movement between fields, editing keys support modifying +field, and plain text adds to or changes data in a current field. The +form library allows you (the forms designer) to bind each navigation +and editing key to any keystroke accepted by <CODE>curses</CODE> + +Fields may have validation conditions on them, so that they check input +data for type and value. The form library supplies a rich set of +pre-defined field types, and makes it relatively easy to define new ones. <P> + +Once its transaction is completed (or aborted), a form may be +<DFN>unposted</DFN> (that is, undisplayed), and finally freed to make +the storage associated with it and its items available for re-use. <P> + +The general flow of control of a form program looks like this: + +<OL> +<LI>Initialize <CODE>curses</CODE>. +<LI>Create the form fields, using <CODE>new_field()</CODE>. +<LI>Create the form using <CODE>new_form()</CODE>. +<LI>Post the form using <CODE>post_form()</CODE>. +<LI>Refresh the screen. +<LI>Process user requests via an input loop. +<LI>Unpost the form using <CODE>unpost_form()</CODE>. +<LI>Free the form, using <CODE>free_form()</CODE>. +<LI>Free the fields using <CODE>free_field()</CODE>. +<LI>Terminate <CODE>curses</CODE>. +</OL> + +Note that this looks much like a menu program; the form library handles +tasks which are in many ways similar, and its interface was obviously +designed to resemble that of the <A HREF="#menu">menu library</A> +wherever possible. <P> + +In forms programs, however, the `process user requests' is somewhat more +complicated than for menus. Besides menu-like navigation operations, +the menu driver loop has to support field editing and data validation. + +<H2><A NAME="fcreate">Creating and Freeing Fields and Forms</A></H2> + +The basic function for creating fields is <CODE>new_field()</CODE>: + +<PRE> +FIELD *new_field(int height, int width, /* new field size */ + int top, int left, /* upper left corner */ + int offscreen, /* number of offscreen rows */ + int nbuf); /* number of working buffers */ +</PRE> + +Menu items always occupy a single row, but forms fields may have +multiple rows. So <CODE>new_field()</CODE> requires you to specify a +width and height (the first two arguments, which mist both be greater +than zero). <P> + +You must also specify the location of the field's upper left corner on +the screen (the third and fourth arguments, which must be zero or +greater). Note that these coordinates are relative to the form +subwindow, which will coincide with <CODE>stdscr</CODE> by default but +need not be <CODE>stdscr</CODE> if you've done an explicit +<CODE>set_form_win()</CODE> call. <P> + +The fifth argument allows you to specify a number of off-screen rows. If +this is zero, the entire field will always be displayed. If it is +nonzero, the form will be scrollable, with only one screen-full (initially +the top part) displayed at any given time. If you make a field dynamic +and grow it so it will no longer fit on the screen, the form will become +scrollable even if the <CODE>offscreen</CODE> argument was initially zero. <P> + +The forms library allocates one working buffer per field; the size of +each buffer is <CODE>((height + offscreen)*width + 1</CODE>, one character +for each position in the field plus a NUL terminator. The sixth +argument is the number of additional data buffers to allocate for the +field; your application can use them for its own purposes. + +<PRE> +FIELD *dup_field(FIELD *field, /* field to copy */ + int top, int left); /* location of new copy */ +</PRE> + +The function <CODE>dup_field()</CODE> duplicates an existing field at a +new location. Size and buffering information are copied; some +attribute flags and status bits are not (see the +<CODE>form_field_new(3X)</CODE> for details). + +<PRE> +FIELD *link_field(FIELD *field, /* field to copy */ + int top, int left); /* location of new copy */ +</PRE> + +The function <CODE>link_field()</CODE> also duplicates an existing field +at a new location. The difference from <CODE>dup_field()</CODE> is that +it arranges for the new field's buffer to be shared with the old one. <P> + +Besides the obvious use in making a field editable from two different +form pages, linked fields give you a way to hack in dynamic labels. If +you declare several fields linked to an original, and then make them +inactive, changes from the original will still be propagated to the +linked fields. <P> + +As with duplicated fields, linked fields have attribute bits separate +from the original. <P> + +As you might guess, all these field-allocations return <CODE>NULL</CODE> if +the field allocation is not possible due to an out-of-memory error or +out-of-bounds arguments. <P> + +To connect fields to a form, use + +<PRE> +FORM *new_form(FIELD **fields); +</PRE> + +This function expects to see a NULL-terminated array of field pointers. +Said fields are connected to a newly-allocated form object; its address +is returned (or else NULL if the allocation fails). <P> + +Note that <CODE>new_field()</CODE> does <EM>not</EM> copy the pointer array +into private storage; if you modify the contents of the pointer array +during forms processing, all manner of bizarre things might happen. Also +note that any given field may only be connected to one form. <P> + +The functions <CODE>free_field()</CODE> and <CODE>free_form</CODE> are available +to free field and form objects. It is an error to attempt to free a field +connected to a form, but not vice-versa; thus, you will generally free +your form objects first. + +<H2><A NAME="fattributes">Fetching and Changing Field Attributes</A></H2> + +Each form field has a number of location and size attributes +associated with it. There are other field attributes used to control +display and editing of the field. Some (for example, the <CODE>O_STATIC</CODE> bit) +involve sufficient complications to be covered in sections of their own +later on. We cover the functions used to get and set several basic +attributes here. <P> + +When a field is created, the attributes not specified by the +<CODE>new_field</CODE> function are copied from an invisible system +default field. In attribute-setting and -fetching functions, the +argument NULL is taken to mean this field. Changes to it persist +as defaults until your forms application terminates. + +<H3><A NAME="fsizes">Fetching Size and Location Data</A></H3> + +You can retrieve field sizes and locations through: + +<PRE> +int field_info(FIELD *field, /* field from which to fetch */ + int *height, *int width, /* field size */ + int *top, int *left, /* upper left corner */ + int *offscreen, /* number of offscreen rows */ + int *nbuf); /* number of working buffers */ +</PRE> + +This function is a sort of inverse of <CODE>new_field()</CODE>; instead of +setting size and location attributes of a new field, it fetches them +from an existing one. + +<H3><A NAME="flocation">Changing the Field Location</A></H3> + +It is possible to move a field's location on the screen: + +<PRE> +int move_field(FIELD *field, /* field to alter */ + int top, int left); /* new upper-left corner */ +</PRE> + +You can, of course. query the current location through <CODE>field_info()</CODE>. + +<H3><A NAME="fjust">The Justification Attribute</A></H3> + +One-line fields may be unjustified, justified right, justified left, +or centered. Here is how you manipulate this attribute: + +<PRE> +int set_field_just(FIELD *field, /* field to alter */ + int justmode); /* mode to set */ + +int field_just(FIELD *field); /* fetch mode of field */ +</PRE> + +The mode values accepted and returned by this functions are +preprocessor macros <CODE>NO_JUSTIFICATION</CODE>, <CODE>JUSTIFY_RIGHT</CODE>, +<CODE>JUSTIFY_LEFT</CODE>, or <CODE>JUSTIFY_CENTER</CODE>. + +<H3><A NAME="fdispatts">Field Display Attributes</A></H3> + +For each field, you can set a foreground attribute for entered +characters, a background attribute for the entire field, and a pad +character for the unfilled portion of the field. You can also +control pagination of the form. <P> + +This group of four field attributes controls the visual appearance +of the field on the screen, without affecting in any way the data +in the field buffer. + +<PRE> +int set_field_fore(FIELD *field, /* field to alter */ + chtype attr); /* attribute to set */ + +chtype field_fore(FIELD *field); /* field to query */ + +int set_field_back(FIELD *field, /* field to alter */ + chtype attr); /* attribute to set */ + +chtype field_back(FIELD *field); /* field to query */ + +int set_field_pad(FIELD *field, /* field to alter */ + int pad); /* pad character to set */ + +chtype field_pad(FIELD *field); + +int set_new_page(FIELD *field, /* field to alter */ + int flag); /* TRUE to force new page */ + +chtype new_page(FIELD *field); /* field to query */ +</PRE> + +The attributes set and returned by the first four functions are normal +<CODE>curses(3x)</CODE> display attribute values (<CODE>A_STANDOUT</CODE>, +<CODE>A_BOLD</CODE>, <CODE>A_REVERSE</CODE> etc). + +The page bit of a field controls whether it is displayed at the start of +a new form screen. + +<H3><A NAME="foptions">Field Option Bits</A></H3> + +There is also a large collection of field option bits you can set to control +various aspects of forms processing. You can manipulate them with these +functions: + +<PRE> +int set_field_opts(FIELD *field, /* field to alter */ + int attr); /* attribute to set */ + +int field_opts_on(FIELD *field, /* field to alter */ + int attr); /* attributes to turn on */ + +int field_opts_off(FIELD *field, /* field to alter */ + int attr); /* attributes to turn off */ + +int field_opts(FIELD *field); /* field to query */ +</PRE> + +By default, all options are on. Here are the available option bits: +<DL> +<DT> O_VISIBLE +<DD> Controls whether the field is visible on the screen. Can be used +during form processing to hide or pop up fields depending on the value +of parent fields. +<DT> O_ACTIVE +<DD> Controls whether the field is active during forms processing (i.e. +visited by form navigation keys). Can be used to make labels or derived +fields with buffer values alterable by the forms application, not the user. +<DT> O_PUBLIC +<DD> Controls whether data is displayed during field entry. If this option is +turned off on a field, the library will accept and edit data in that field, +but it will not be displayed and the visible field cursor will not move. +You can turn off the O_PUBLIC bit to define password fields. +<DT> O_EDIT +<DD> Controls whether the field's data can be modified. When this option is +off, all editing requests except <CODE>REQ_PREV_CHOICE</CODE> and +<CODE>REQ_NEXT_CHOICE</CODE> will fail. Such read-only fields may be useful for +help messages. +<DT> O_WRAP +<DD> Controls word-wrapping in multi-line fields. Normally, when any +character of a (blank-separated) word reaches the end of the current line, the +entire word is wrapped to the next line (assuming there is one). When this +option is off, the word will be split across the line break. +<DT> O_BLANK +<DD> Controls field blanking. When this option is on, entering a character at +the first field position erases the entire field (except for the just-entered +character). +<DT> O_AUTOSKIP +<DD> Controls automatic skip to next field when this one fills. Normally, +when the forms user tries to type more data into a field than will fit, +the editing location jumps to next field. When this option is off, the +user's cursor will hang at the end of the field. This option is ignored +in dynamic fields that have not reached their size limit. +<DT> O_NULLOK +<DD> Controls whether <A HREF="#fvalidation">validation</A> is applied to +blank fields. Normally, it is not; the user can leave a field blank +without invoking the usual validation check on exit. If this option is +off on a field, exit from it will invoke a validation check. +<DT> O_PASSOK +<DD> Controls whether validation occurs on every exit, or only after +the field is modified. Normally the latter is true. Setting O_PASSOK +may be useful if your field's validation function may change during +forms processing. +<DT> O_STATIC +<DD> Controls whether the field is fixed to its initial dimensions. If you +turn this off, the field becomes <A HREF="#fdynamic">dynamic</A> and will +stretch to fit entered data. +</DL> + +A field's options cannot be changed while the field is currently selected. +However, options may be changed on posted fields that are not current. <P> + +The option values are bit-masks and can be composed with logical-or in +the obvious way. + +<H2><A NAME="fstatus">Field Status</A></H2> + +Every field has a status flag, which is set to FALSE when the field is +created and TRUE when the value in field buffer 0 changes. This flag can +be queried and set directly: + +<PRE> +int set_field_status(FIELD *field, /* field to alter */ + int status); /* mode to set */ + +int field_status(FIELD *field); /* fetch mode of field */ +</PRE> + +Setting this flag under program control can be useful if you use the same +form repeatedly, looking for modified fields each time. <P> + +Calling <CODE>field_status()</CODE> on a field not currently selected +for input will return a correct value. Calling <CODE>field_status()</CODE> on a +field that is currently selected for input may not necessarily give a +correct field status value, because entered data isn't necessarily copied to +buffer zero before the exit validation check. + +To guarantee that the returned status value reflects reality, call +<CODE>field_status()</CODE> either (1) in the field's exit validation check +routine, (2) from the field's or form's initialization or termination +hooks, or (3) just after a <CODE>REQ_VALIDATION</CODE> request has been +processed by the forms driver. + +<H2><A NAME="fuser">Field User Pointer</A></H2> + +Each field structure contains one character pointer slot that is not used +by the forms library. It is intended to be used by applications to store +private per-field data. You can manipulate it with: + +<PRE> +int set_field_userptr(FIELD *field, /* field to alter */ + char *userptr); /* mode to set */ + +char *field_userptr(FIELD *field); /* fetch mode of field */ +</PRE> + +(Properly, this user pointer field ought to have <CODE>(void *)</CODE> type. +The <CODE>(char *)</CODE> type is retained for System V compatibility.) <P> + +It is valid to set the user pointer of the default field (with a +<CODE>set_field_userptr()</CODE> call passed a NULL field pointer.) +When a new field is created, the default-field user pointer is copied +to initialize the new field's user pointer. + +<H2><A NAME="fdynamic">Variable-Sized Fields</A></H2> + +Normally, a field is fixed at the size specified for it at creation +time. If, however, you turn off its O_STATIC bit, it becomes +<DFN>dynamic</DFN> and will automatically resize itself to accommodate +data as it is entered. If the field has extra buffers associated with it, +they will grow right along with the main input buffer. <P> + +A one-line dynamic field will have a fixed height (1) but variable +width, scrolling horizontally to display data within the field area as +originally dimensioned and located. A multi-line dynamic field will +have a fixed width, but variable height (number of rows), scrolling +vertically to display data within the field area as originally +dimensioned and located. <P> + +Normally, a dynamic field is allowed to grow without limit. But it is +possible to set an upper limit on the size of a dynamic field. You do +it with this function: + +<PRE> +int set_max_field(FIELD *field, /* field to alter (may not be NULL) */ + int max_size); /* upper limit on field size */ +</PRE> + +If the field is one-line, <CODE>max_size</CODE> is taken to be a column size +limit; if it is multi-line, it is taken to be a line size limit. To disable +any limit, use an argument of zero. The growth limit can be changed whether +or not the O_STATIC bit is on, but has no effect until it is. <P> + +The following properties of a field change when it becomes dynamic: + +<UL> +<LI>If there is no growth limit, there is no final position of the field; +therefore <CODE>O_AUTOSKIP</CODE> and <CODE>O_NL_OVERLOAD</CODE> are ignored. +<LI>Field justification will be ignored (though whatever justification is +set up will be retained internally and can be queried). +<LI>The <CODE>dup_field()</CODE> and <CODE>link_field()</CODE> calls copy +dynamic-buffer sizes. If the <CODE>O_STATIC</CODE> option is set on one of a +collection of links, buffer resizing will occur only when the field is +edited through that link. +<LI>The call <CODE>field_info()</CODE> will retrieve the original static size of +the field; use <CODE>dynamic_field_info()</CODE> to get the actual dynamic size. +</UL> + +<H2><A NAME="fvalidation">Field Validation</A></H2> + +By default, a field will accept any data that will fit in its input buffer. +However, it is possible to attach a validation type to a field. If you do +this, any attempt to leave the field while it contains data that doesn't +match the validation type will fail. Some validation types also have a +character-validity check for each time a character is entered in the field. <P> + +A field's validation check (if any) is not called when +<CODE>set_field_buffer()</CODE> modifies the input buffer, nor when that buffer +is changed through a linked field. <P> + +The <CODE>form</CODE> library provides a rich set of pre-defined validation +types, and gives you the capability to define custom ones of your own. You +can examine and change field validation attributes with the following +functions: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + FIELDTYPE *ftype, /* type to associate */ + ...); /* additional arguments*/ + +FIELDTYPE *field_type(FIELD *field); /* field to query */ +</PRE> + +The validation type of a field is considered an attribute of the field. As +with other field attributes, Also, doing <CODE>set_field_type()</CODE> with a +<CODE>NULL</CODE> field default will change the system default for validation of +newly-created fields. <P> + +Here are the pre-defined validation types: + +<H3><A NAME="ftype_alpha">TYPE_ALPHA</A></H3> + +This field type accepts alphabetic data; no blanks, no digits, no special +characters (this is checked at character-entry time). It is set up with: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + TYPE_ALPHA, /* type to associate */ + int width); /* maximum width of field */ +</PRE> + +The <CODE>width</CODE> argument sets a minimum width of data. Typically +you'll want to set this to the field width; if it's greater than the +field width, the validation check will always fail. A minimum width +of zero makes field completion optional. + +<H3><A NAME="ftype_alnum">TYPE_ALNUM</A></H3> + +This field type accepts alphabetic data and digits; no blanks, no special +characters (this is checked at character-entry time). It is set up with: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + TYPE_ALNUM, /* type to associate */ + int width); /* maximum width of field */ +</PRE> + +The <CODE>width</CODE> argument sets a minimum width of data. As with +TYPE_ALPHA, typically you'll want to set this to the field width; if it's +greater than the field width, the validation check will always fail. A +minimum width of zero makes field completion optional. + +<H3><A NAME="ftype_enum">TYPE_ENUM</A></H3> + +This type allows you to restrict a field's values to be among a specified +set of string values (for example, the two-letter postal codes for U.S. +states). It is set up with: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + TYPE_ENUM, /* type to associate */ + char **valuelist; /* list of possible values */ + int checkcase; /* case-sensitive? */ + int checkunique); /* must specify uniquely? */ +</PRE> + +The <CODE>valuelist</CODE> parameter must point at a NULL-terminated list of +valid strings. The <CODE>checkcase</CODE> argument, if true, makes comparison +with the string case-sensitive. <P> + +When the user exits a TYPE_ENUM field, the validation procedure tries to +complete the data in the buffer to a valid entry. If a complete choice string +has been entered, it is of course valid. But it is also possible to enter a +prefix of a valid string and have it completed for you. <P> + +By default, if you enter such a prefix and it matches more than one value +in the string list, the prefix will be completed to the first matching +value. But the <CODE>checkunique</CODE> argument, if true, requires prefix +matches to be unique in order to be valid. <P> + +The <CODE>REQ_NEXT_CHOICE</CODE> and <CODE>REQ_PREV_CHOICE</CODE> input requests +can be particularly useful with these fields. + +<H3><A NAME="ftype_integer">TYPE_INTEGER</A></H3> + +This field type accepts an integer. It is set up as follows: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + TYPE_INTEGER, /* type to associate */ + int padding, /* # places to zero-pad to */ + int vmin, int vmax); /* valid range */ +</PRE> + +Valid characters consist of an optional leading minus and digits. +The range check is performed on exit. If the range maximum is less +than or equal to the minimum, the range is ignored. <P> + +If the value passes its range check, it is padded with as many leading +zero digits as necessary to meet the padding argument. <P> + +A <CODE>TYPE_INTEGER</CODE> value buffer can conveniently be interpreted +with the C library function <CODE>atoi(3)</CODE>. + +<H3><A NAME="ftype_numeric">TYPE_NUMERIC</A></H3> + +This field type accepts a decimal number. It is set up as follows: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + TYPE_NUMERIC, /* type to associate */ + int padding, /* # places of precision */ + double vmin, double vmax); /* valid range */ +</PRE> + +Valid characters consist of an optional leading minus and digits. possibly +including a decimal point. If your system supports locale's, the decimal point +character used must be the one defined by your locale. The range check is +performed on exit. If the range maximum is less than or equal to the minimum, +the range is ignored. <P> + +If the value passes its range check, it is padded with as many trailing +zero digits as necessary to meet the padding argument. <P> + +A <CODE>TYPE_NUMERIC</CODE> value buffer can conveniently be interpreted +with the C library function <CODE>atof(3)</CODE>. + +<H3><A NAME="ftype_regexp">TYPE_REGEXP</A></H3> + +This field type accepts data matching a regular expression. It is set up +as follows: + +<PRE> +int set_field_type(FIELD *field, /* field to alter */ + TYPE_REGEXP, /* type to associate */ + char *regexp); /* expression to match */ +</PRE> + +The syntax for regular expressions is that of <CODE>regcomp(3)</CODE>. +The check for regular-expression match is performed on exit. + +<H2><A NAME="fbuffer">Direct Field Buffer Manipulation</A></H2> + +The chief attribute of a field is its buffer contents. When a form has +been completed, your application usually needs to know the state of each +field buffer. You can find this out with: + +<PRE> +char *field_buffer(FIELD *field, /* field to query */ + int bufindex); /* number of buffer to query */ +</PRE> + +Normally, the state of the zero-numbered buffer for each field is set by +the user's editing actions on that field. It's sometimes useful to be able +to set the value of the zero-numbered (or some other) buffer from your +application: + +<PRE> +int set_field_buffer(FIELD *field, /* field to alter */ + int bufindex, /* number of buffer to alter */ + char *value); /* string value to set */ +</PRE> + +If the field is not large enough and cannot be resized to a sufficiently +large size to contain the specified value, the value will be truncated +to fit. <P> + +Calling <CODE>field_buffer()</CODE> with a null field pointer will raise an +error. Calling <CODE>field_buffer()</CODE> on a field not currently selected +for input will return a correct value. Calling <CODE>field_buffer()</CODE> on a +field that is currently selected for input may not necessarily give a +correct field buffer value, because entered data isn't necessarily copied to +buffer zero before the exit validation check. + +To guarantee that the returned buffer value reflects on-screen reality, +call <CODE>field_buffer()</CODE> either (1) in the field's exit validation +check routine, (2) from the field's or form's initialization or termination +hooks, or (3) just after a <CODE>REQ_VALIDATION</CODE> request has been processed +by the forms driver. + +<H2><A NAME="formattrs">Attributes of Forms</A></H2> + +As with field attributes, form attributes inherit a default from a +system default form structure. These defaults can be queried or set by +of these functions using a form-pointer argument of <CODE>NULL</CODE>. <P> + +The principal attribute of a form is its field list. You can query +and change this list with: + +<PRE> +int set_form_fields(FORM *form, /* form to alter */ + FIELD **fields); /* fields to connect */ + +char *form_fields(FORM *form); /* fetch fields of form */ + +int field_count(FORM *form); /* count connect fields */ +</PRE> + +The second argument of <CODE>set_form_fields()</CODE> may be a +NULL-terminated field pointer array like the one required by +<CODE>new_form()</CODE>. In that case, the old fields of the form are +disconnected but not freed (and eligible to be connected to other +forms), then the new fields are connected. <P> + +It may also be null, in which case the old fields are disconnected +(and not freed) but no new ones are connected. <P> + +The <CODE>field_count()</CODE> function simply counts the number of fields +connected to a given from. It returns -1 if the form-pointer argument +is NULL. + +<H2><A NAME="fdisplay">Control of Form Display</A></H2> + +In the overview section, you saw that to display a form you normally +start by defining its size (and fields), posting it, and refreshing +the screen. There is an hidden step before posting, which is the +association of the form with a frame window (actually, a pair of +windows) within which it will be displayed. By default, the forms +library associates every form with the full-screen window +<CODE>stdscr</CODE>. <P> + +By making this step explicit, you can associate a form with a declared +frame window on your screen display. This can be useful if you want to +adapt the form display to different screen sizes, dynamically tile +forms on the screen, or use a form as part of an interface layout +managed by <A HREF="#panels">panels</A>. <P> + +The two windows associated with each form have the same functions as +their analogues in the <A HREF="#menu">menu library</A>. Both these +windows are painted when the form is posted and erased when the form +is unposted. <P> + +The outer or frame window is not otherwise touched by the form +routines. It exists so the programmer can associate a title, a +border, or perhaps help text with the form and have it properly +refreshed or erased at post/unpost time. The inner window or subwindow +is where the current form page is actually displayed. <P> + +In order to declare your own frame window for a form, you'll need to +know the size of the form's bounding rectangle. You can get this +information with: + +<PRE> +int scale_form(FORM *form, /* form to query */ + int *rows, /* form rows */ + int *cols); /* form cols */ +</PRE> + +The form dimensions are passed back in the locations pointed to by +the arguments. Once you have this information, you can use it to +declare of windows, then use one of these functions: + +<PRE> +int set_form_win(FORM *form, /* form to alter */ + WINDOW *win); /* frame window to connect */ + +WINDOW *form_win(FORM *form); /* fetch frame window of form */ + +int set_form_sub(FORM *form, /* form to alter */ + WINDOW *win); /* form subwindow to connect */ + +WINDOW *form_sub(FORM *form); /* fetch form subwindow of form */ +</PRE> + +Note that curses operations, including <CODE>refresh()</CODE>, on the form, +should be done on the frame window, not the form subwindow. <P> + +It is possible to check from your application whether all of a +scrollable field is actually displayed within the menu subwindow. Use +these functions: + +<PRE> +int data_ahead(FORM *form); /* form to be queried */ + +int data_behind(FORM *form); /* form to be queried */ +</PRE> + +The function <CODE>data_ahead()</CODE> returns TRUE if (a) the current +field is one-line and has undisplayed data off to the right, (b) the current +field is multi-line and there is data off-screen below it. <P> + +The function <CODE>data_behind()</CODE> returns TRUE if the first (upper +left hand) character position is off-screen (not being displayed). <P> + +Finally, there is a function to restore the form window's cursor to the +value expected by the forms driver: + +<PRE> +int pos_form_cursor(FORM *) /* form to be queried */ +</PRE> + +If your application changes the form window cursor, call this function before +handing control back to the forms driver in order to re-synchronize it. + +<H2><A NAME="fdriver">Input Processing in the Forms Driver</A></H2> + +The function <CODE>form_driver()</CODE> handles virtualized input requests +for form navigation, editing, and validation requests, just as +<CODE>menu_driver</CODE> does for menus (see the section on <A +HREF="#minput">menu input handling</A>). + +<PRE> +int form_driver(FORM *form, /* form to pass input to */ + int request); /* form request code */ +</PRE> + +Your input virtualization function needs to take input and then convert it +to either an alphanumeric character (which is treated as data to be +entered in the currently-selected field), or a forms processing request. <P> + +The forms driver provides hooks (through input-validation and +field-termination functions) with which your application code can check +that the input taken by the driver matched what was expected. + +<H3><A NAME="fpage">Page Navigation Requests</A></H3> + +These requests cause page-level moves through the form, +triggering display of a new form screen. + +<DL> +<DT> <CODE>REQ_NEXT_PAGE</CODE> +<DD> Move to the next form page. +<DT> <CODE>REQ_PREV_PAGE</CODE> +<DD> Move to the previous form page. +<DT> <CODE>REQ_FIRST_PAGE</CODE> +<DD> Move to the first form page. +<DT> <CODE>REQ_LAST_PAGE</CODE> +<DD> Move to the last form page. +</DL> + +These requests treat the list as cyclic; that is, <CODE>REQ_NEXT_PAGE</CODE> +from the last page goes to the first, and <CODE>REQ_PREV_PAGE</CODE> from +the first page goes to the last. + +<H3><A NAME="ffield">Inter-Field Navigation Requests</A></H3> + +These requests handle navigation between fields on the same page. + +<DL> +<DT> <CODE>REQ_NEXT_FIELD</CODE> +<DD> Move to next field. +<DT> <CODE>REQ_PREV_FIELD</CODE> +<DD> Move to previous field. +<DT> <CODE>REQ_FIRST_FIELD</CODE> +<DD> Move to the first field. +<DT> <CODE>REQ_LAST_FIELD</CODE> +<DD> Move to the last field. +<DT> <CODE>REQ_SNEXT_FIELD</CODE> +<DD> Move to sorted next field. +<DT> <CODE>REQ_SPREV_FIELD</CODE> +<DD> Move to sorted previous field. +<DT> <CODE>REQ_SFIRST_FIELD</CODE> +<DD> Move to the sorted first field. +<DT> <CODE>REQ_SLAST_FIELD</CODE> +<DD> Move to the sorted last field. +<DT> <CODE>REQ_LEFT_FIELD</CODE> +<DD> Move left to field. +<DT> <CODE>REQ_RIGHT_FIELD</CODE> +<DD> Move right to field. +<DT> <CODE>REQ_UP_FIELD</CODE> +<DD> Move up to field. +<DT> <CODE>REQ_DOWN_FIELD</CODE> +<DD> Move down to field. +</DL> + +These requests treat the list of fields on a page as cyclic; that is, +<CODE>REQ_NEXT_FIELD</CODE> from the last field goes to the first, and +<CODE>REQ_PREV_FIELD</CODE> from the first field goes to the last. The +order of the fields for these (and the <CODE>REQ_FIRST_FIELD</CODE> and +<CODE>REQ_LAST_FIELD</CODE> requests) is simply the order of the field +pointers in the form array (as set up by <CODE>new_form()</CODE> or +<CODE>set_form_fields()</CODE> <P> + +It is also possible to traverse the fields as if they had been sorted in +screen-position order, so the sequence goes left-to-right and top-to-bottom. +To do this, use the second group of four sorted-movement requests. <P> + +Finally, it is possible to move between fields using visual directions up, +down, right, and left. To accomplish this, use the third group of four +requests. Note, however, that the position of a form for purposes of these +requests is its upper-left corner. <P> + +For example, suppose you have a multi-line field B, and two +single-line fields A and C on the same line with B, with A to the left +of B and C to the right of B. A <CODE>REQ_MOVE_RIGHT</CODE> from A will +go to B only if A, B, and C <EM>all</EM> share the same first line; +otherwise it will skip over B to C. + +<H3><A NAME="fifield">Intra-Field Navigation Requests</A></H3> + +These requests drive movement of the edit cursor within the currently +selected field. + +<DL> +<DT> <CODE>REQ_NEXT_CHAR</CODE> +<DD> Move to next character. +<DT> <CODE>REQ_PREV_CHAR</CODE> +<DD> Move to previous character. +<DT> <CODE>REQ_NEXT_LINE</CODE> +<DD> Move to next line. +<DT> <CODE>REQ_PREV_LINE</CODE> +<DD> Move to previous line. +<DT> <CODE>REQ_NEXT_WORD</CODE> +<DD> Move to next word. +<DT> <CODE>REQ_PREV_WORD</CODE> +<DD> Move to previous word. +<DT> <CODE>REQ_BEG_FIELD</CODE> +<DD> Move to beginning of field. +<DT> <CODE>REQ_END_FIELD</CODE> +<DD> Move to end of field. +<DT> <CODE>REQ_BEG_LINE</CODE> +<DD> Move to beginning of line. +<DT> <CODE>REQ_END_LINE</CODE> +<DD> Move to end of line. +<DT> <CODE>REQ_LEFT_CHAR</CODE> +<DD> Move left in field. +<DT> <CODE>REQ_RIGHT_CHAR</CODE> +<DD> Move right in field. +<DT> <CODE>REQ_UP_CHAR</CODE> +<DD> Move up in field. +<DT> <CODE>REQ_DOWN_CHAR</CODE> +<DD> Move down in field. +</DL> + +Each <EM>word</EM> is separated from the previous and next characters +by whitespace. The commands to move to beginning and end of line or field +look for the first or last non-pad character in their ranges. + +<H3><A NAME="fscroll">Scrolling Requests</A></H3> + +Fields that are dynamic and have grown and fields explicitly created +with offscreen rows are scrollable. One-line fields scroll horizontally; +multi-line fields scroll vertically. Most scrolling is triggered by +editing and intra-field movement (the library scrolls the field to keep the +cursor visible). It is possible to explicitly request scrolling with the +following requests: + +<DL> +<DT> <CODE>REQ_SCR_FLINE</CODE> +<DD> Scroll vertically forward a line. +<DT> <CODE>REQ_SCR_BLINE</CODE> +<DD> Scroll vertically backward a line. +<DT> <CODE>REQ_SCR_FPAGE</CODE> +<DD> Scroll vertically forward a page. +<DT> <CODE>REQ_SCR_BPAGE</CODE> +<DD> Scroll vertically backward a page. +<DT> <CODE>REQ_SCR_FHPAGE</CODE> +<DD> Scroll vertically forward half a page. +<DT> <CODE>REQ_SCR_BHPAGE</CODE> +<DD> Scroll vertically backward half a page. +<DT> <CODE>REQ_SCR_FCHAR</CODE> +<DD> Scroll horizontally forward a character. +<DT> <CODE>REQ_SCR_BCHAR</CODE> +<DD> Scroll horizontally backward a character. +<DT> <CODE>REQ_SCR_HFLINE</CODE> +<DD> Scroll horizontally one field width forward. +<DT> <CODE>REQ_SCR_HBLINE</CODE> +<DD> Scroll horizontally one field width backward. +<DT> <CODE>REQ_SCR_HFHALF</CODE> +<DD> Scroll horizontally one half field width forward. +<DT> <CODE>REQ_SCR_HBHALF</CODE> +<DD> Scroll horizontally one half field width backward. +</DL> + +For scrolling purposes, a <EM>page</EM> of a field is the height +of its visible part. + +<H3><A NAME="fedit">Editing Requests</A></H3> + +When you pass the forms driver an ASCII character, it is treated as a +request to add the character to the field's data buffer. Whether this +is an insertion or a replacement depends on the field's edit mode +(insertion is the default. <P> + +The following requests support editing the field and changing the edit +mode: + +<DL> +<DT> <CODE>REQ_INS_MODE</CODE> +<DD> Set insertion mode. +<DT> <CODE>REQ_OVL_MODE</CODE> +<DD> Set overlay mode. +<DT> <CODE>REQ_NEW_LINE</CODE> +<DD> New line request (see below for explanation). +<DT> <CODE>REQ_INS_CHAR</CODE> +<DD> Insert space at character location. +<DT> <CODE>REQ_INS_LINE</CODE> +<DD> Insert blank line at character location. +<DT> <CODE>REQ_DEL_CHAR</CODE> +<DD> Delete character at cursor. +<DT> <CODE>REQ_DEL_PREV</CODE> +<DD> Delete previous word at cursor. +<DT> <CODE>REQ_DEL_LINE</CODE> +<DD> Delete line at cursor. +<DT> <CODE>REQ_DEL_WORD</CODE> +<DD> Delete word at cursor. +<DT> <CODE>REQ_CLR_EOL</CODE> +<DD> Clear to end of line. +<DT> <CODE>REQ_CLR_EOF</CODE> +<DD> Clear to end of field. +<DT> <CODE>REQ_CLEAR_FIELD</CODE> +<DD> Clear entire field. +</DL> + +The behavior of the <CODE>REQ_NEW_LINE</CODE> and <CODE>REQ_DEL_PREV</CODE> requests +is complicated and partly controlled by a pair of forms options. +The special cases are triggered when the cursor is at the beginning of +a field, or on the last line of the field. <P> + +First, we consider <CODE>REQ_NEW_LINE</CODE>: <P> + +The normal behavior of <CODE>REQ_NEW_LINE</CODE> in insert mode is to break the +current line at the position of the edit cursor, inserting the portion of +the current line after the cursor as a new line following the current +and moving the cursor to the beginning of that new line (you may think +of this as inserting a newline in the field buffer). <P> + +The normal behavior of <CODE>REQ_NEW_LINE</CODE> in overlay mode is to clear the +current line from the position of the edit cursor to end of line. +The cursor is then moved to the beginning of the next line. <P> + +However, <CODE>REQ_NEW_LINE</CODE> at the beginning of a field, or on the +last line of a field, instead does a <CODE>REQ_NEXT_FIELD</CODE>. +<CODE>O_NL_OVERLOAD</CODE> option is off, this special action is +disabled. <P> + +Now, let us consider <CODE>REQ_DEL_PREV</CODE>: <P> + +The normal behavior of <CODE>REQ_DEL_PREV</CODE> is to delete the previous +character. If insert mode is on, and the cursor is at the start of a +line, and the text on that line will fit on the previous one, it +instead appends the contents of the current line to the previous one +and deletes the current line (you may think of this as deleting a +newline from the field buffer). <P> + +However, <CODE>REQ_DEL_PREV</CODE> at the beginning of a field is instead +treated as a <CODE>REQ_PREV_FIELD</CODE>. <P> If the +<CODE>O_BS_OVERLOAD</CODE> option is off, this special action is +disabled and the forms driver just returns <CODE>E_REQUEST_DENIED</CODE>. <P> + +See <A HREF="#frmoptions">Form Options</A> for discussion of how to set +and clear the overload options. + +<H3><A NAME="forder">Order Requests</A></H3> + +If the type of your field is ordered, and has associated functions +for getting the next and previous values of the type from a given value, +there are requests that can fetch that value into the field buffer: + +<DL> +<DT> <CODE>REQ_NEXT_CHOICE</CODE> +<DD> Place the successor value of the current value in the buffer. +<DT> <CODE>REQ_PREV_CHOICE</CODE> +<DD> Place the predecessor value of the current value in the buffer. +</DL> + +Of the built-in field types, only <CODE>TYPE_ENUM</CODE> has built-in successor +and predecessor functions. When you define a field type of your own +(see <A HREF="#fcustom">Custom Validation Types</A>), you can associate +our own ordering functions. + +<H3><A NAME="fappcmds">Application Commands</A></H3> + +Form requests are represented as integers above the <CODE>curses</CODE> value +greater than <CODE>KEY_MAX</CODE> and less than or equal to the constant +<CODE>MAX_COMMAND</CODE>. If your input-virtualization routine returns a +value above <CODE>MAX_COMMAND</CODE>, the forms driver will ignore it. + +<H2><A NAME="fhooks">Field Change Hooks</A></H2> + +It is possible to set function hooks to be executed whenever the +current field or form changes. Here are the functions that support this: + +<PRE> +typedef void (*HOOK)(); /* pointer to function returning void */ + +int set_form_init(FORM *form, /* form to alter */ + HOOK hook); /* initialization hook */ + +HOOK form_init(FORM *form); /* form to query */ + +int set_form_term(FORM *form, /* form to alter */ + HOOK hook); /* termination hook */ + +HOOK form_term(FORM *form); /* form to query */ + +int set_field_init(FORM *form, /* form to alter */ + HOOK hook); /* initialization hook */ + +HOOK field_init(FORM *form); /* form to query */ + +int set_field_term(FORM *form, /* form to alter */ + HOOK hook); /* termination hook */ + +HOOK field_term(FORM *form); /* form to query */ +</PRE> + +These functions allow you to either set or query four different hooks. +In each of the set functions, the second argument should be the +address of a hook function. These functions differ only in the timing +of the hook call. + +<DL> +<DT> form_init +<DD> This hook is called when the form is posted; also, just after +each page change operation. +<DT> field_init +<DD> This hook is called when the form is posted; also, just after +each field change +<DT> field_term +<DD> This hook is called just after field validation; that is, just before +the field is altered. It is also called when the form is unposted. +<DT> form_term +<DD> This hook is called when the form is unposted; also, just before +each page change operation. +</DL> + +Calls to these hooks may be triggered +<OL> +<LI>When user editing requests are processed by the forms driver +<LI>When the current page is changed by <CODE>set_current_field()</CODE> call +<LI>When the current field is changed by a <CODE>set_form_page()</CODE> call +</OL> + +See <A NAME="ffocus">Field Change Commands</A> for discussion of the latter +two cases. <P> + +You can set a default hook for all fields by passing one of the set functions +a NULL first argument. <P> + +You can disable any of these hooks by (re)setting them to NULL, the default +value. + +<H2><A HREF="#ffocus">Field Change Commands</A></H2> + +Normally, navigation through the form will be driven by the user's +input requests. But sometimes it is useful to be able to move the +focus for editing and viewing under control of your application, or +ask which field it currently is in. The following functions help you +accomplish this: + +<PRE> +int set_current_field(FORM *form, /* form to alter */ + FIELD *field); /* field to shift to */ + +FIELD *current_field(FORM *form); /* form to query */ + +int field_index(FORM *form, /* form to query */ + FIELD *field); /* field to get index of */ +</PRE> + +The function <CODE>field_index()</CODE> returns the index of the given field +in the given form's field array (the array passed to <CODE>new_form()</CODE> or +<CODE>set_form_fields()</CODE>). <P> + +The initial current field of a form is the first active field on the +first page. The function <CODE>set_form_fields()</CODE> resets this.<P> + +It is also possible to move around by pages. + +<PRE> +int set_form_page(FORM *form, /* form to alter */ + int page); /* page to go to (0-origin) */ + +int form_page(FORM *form); /* return form's current page */ +</PRE> + +The initial page of a newly-created form is 0. The function +<CODE>set_form_fields()</CODE> resets this. + +<H2><A NAME="frmoptions">Form Options</A></H2> + +Like fields, forms may have control option bits. They can be changed +or queried with these functions: + +<PRE> +int set_form_opts(FORM *form, /* form to alter */ + int attr); /* attribute to set */ + +int form_opts_on(FORM *form, /* form to alter */ + int attr); /* attributes to turn on */ + +int form_opts_off(FORM *form, /* form to alter */ + int attr); /* attributes to turn off */ + +int form_opts(FORM *form); /* form to query */ +</PRE> + +By default, all options are on. Here are the available option bits: + +<DL> +<DT> O_NL_OVERLOAD +<DD> Enable overloading of <CODE>REQ_NEW_LINE</CODE> as described in <A +href="#fedit">Editing Requests</A>. The value of this option is +ignored on dynamic fields that have not reached their size limit; +these have no last line, so the circumstances for triggering a +<CODE>REQ_NEXT_FIELD</CODE> never arise. +<DT> O_BS_OVERLOAD +<DD> Enable overloading of <CODE>REQ_DEL_PREV</CODE> as described in +<A href="#fedit">Editing Requests</A>. +</DL> + +The option values are bit-masks and can be composed with logical-or in +the obvious way. + +<H2><A NAME="fcustom">Custom Validation Types</A></H2> + +The <CODE>form</CODE> library gives you the capability to define custom +validation types of your own. Further, the optional additional arguments +of <CODE>set_field_type</CODE> effectively allow you to parameterize validation +types. Most of the complications in the validation-type interface have to +do with the handling of the additional arguments within custom validation +functions. + +<H3><A NAME="flinktypes">Union Types</A></H3> + +The simplest way to create a custom data type is to compose it from two +preexisting ones: + +<PRE> +FIELD *link_fieldtype(FIELDTYPE *type1, + FIELDTYPE *type2); +</PRE> + +This function creates a field type that will accept any of the values +legal for either of its argument field types (which may be either +predefined or programmer-defined). + +If a <CODE>set_field_type()</CODE> call later requires arguments, the new +composite type expects all arguments for the first type, than all arguments +for the second. Order functions (see <A HREF="#forder">Order Requests</A>) +associated with the component types will work on the composite; what it does +is check the validation function for the first type, then for the second, to +figure what type the buffer contents should be treated as. + +<H3><A NAME="fnewtypes">New Field Types</A></H3> + +To create a field type from scratch, you need to specify one or both of the +following things: + +<UL> +<LI>A character-validation function, to check each character as it is entered. +<LI>A field-validation function to be applied on exit from the field. +</UL> + +Here's how you do that: +<PRE> +typedef int (*HOOK)(); /* pointer to function returning int */ + +FIELDTYPE *new_fieldtype(HOOK f_validate, /* field validator */ + HOOK c_validate) /* character validator */ + + +int free_fieldtype(FIELDTYPE *ftype); /* type to free */ +</PRE> + +At least one of the arguments of <CODE>new_fieldtype()</CODE> must be +non-NULL. The forms driver will automatically call the new type's +validation functions at appropriate points in processing a field of +the new type. <P> + +The function <CODE>free_fieldtype()</CODE> deallocates the argument +fieldtype, freeing all storage associated with it. <P> + +Normally, a field validator is called when the user attempts to +leave the field. Its first argument is a field pointer, from which it +can get to field buffer 0 and test it. If the function returns TRUE, +the operation succeeds; if it returns FALSE, the edit cursor stays in +the field. <P> + +A character validator gets the character passed in as a first argument. +It too should return TRUE if the character is valid, FALSE otherwise. + +<H3><A NAME="fcheckargs">Validation Function Arguments</A></H3> + +Your field- and character- validation functions will be passed a +second argument as well. This second argument is the address of a +structure (which we'll call a <EM>pile</EM>) built from any of the +field-type-specific arguments passed to <CODE>set_field_type()</CODE>. If +no such arguments are defined for the field type, this pile pointer +argument will be NULL. <P> + +In order to arrange for such arguments to be passed to your validation +functions, you must associate a small set of storage-management functions +with the type. The forms driver will use these to synthesize a pile +from the trailing arguments of each <CODE>set_field_type()</CODE> argument, and +a pointer to the pile will be passed to the validation functions. <P> + +Here is how you make the association: + +<PRE> +typedef char *(*PTRHOOK)(); /* pointer to function returning (char *) */ +typedef void (*VOIDHOOK)(); /* pointer to function returning void */ + +int set_fieldtype_arg(FIELDTYPE *type, /* type to alter */ + PTRHOOK make_str, /* make structure from args */ + PTRHOOK copy_str, /* make copy of structure */ + VOIDHOOK free_str); /* free structure storage */ +</PRE> + +Here is how the storage-management hooks are used: + +<DL> +<DT> <CODE>make_str</CODE> +<DD> This function is called by <CODE>set_field_type()</CODE>. It gets one +argument, a <CODE>va_list</CODE> of the type-specific arguments passed to +<CODE>set_field_type()</CODE>. It is expected to return a pile pointer to a data +structure that encapsulates those arguments. +<DT> <CODE>copy_str</CODE> +<DD> This function is called by form library functions that allocate new +field instances. It is expected to take a pile pointer, copy the pile +to allocated storage, and return the address of the pile copy. +<DT> <CODE>free_str</CODE> +<DD> This function is called by field- and type-deallocation routines in the +library. It takes a pile pointer argument, and is expected to free the +storage of that pile. +</DL> + +The <CODE>make_str</CODE> and <CODE>copy_str</CODE> functions may return NULL to +signal allocation failure. The library routines will that call them will +return error indication when this happens. Thus, your validation functions +should never see a NULL file pointer and need not check specially for it. + +<H3><A NAME="fcustorder">Order Functions For Custom Types</A></H3> + +Some custom field types are simply ordered in the same well-defined way +that <CODE>TYPE_ENUM</CODE> is. For such types, it is possible to define +successor and predecessor functions to support the <CODE>REQ_NEXT_CHOICE</CODE> +and <CODE>REQ_PREV_CHOICE</CODE> requests. Here's how: + +<PRE> +typedef int (*INTHOOK)(); /* pointer to function returning int */ + +int set_fieldtype_arg(FIELDTYPE *type, /* type to alter */ + INTHOOK succ, /* get successor value */ + INTHOOK pred); /* get predecessor value */ +</PRE> + +The successor and predecessor arguments will each be passed two arguments; +a field pointer, and a pile pointer (as for the validation functions). They +are expected to use the function <CODE>field_buffer()</CODE> to read the +current value, and <CODE>set_field_buffer()</CODE> on buffer 0 to set the next +or previous value. Either hook may return TRUE to indicate success (a +legal next or previous value was set) or FALSE to indicate failure. + +<H3><A NAME="fcustprobs">Avoiding Problems</A></H3> + +The interface for defining custom types is complicated and tricky. +Rather than attempting to create a custom type entirely from scratch, +you should start by studying the library source code for whichever of +the pre-defined types seems to be closest to what you want. <P> + +Use that code as a model, and evolve it towards what you really want. +You will avoid many problems and annoyances that way. The code +in the <CODE>ncurses</CODE> library has been specifically exempted from +the package copyright to support this. <P> + +If your custom type defines order functions, have do something intuitive +with a blank field. A useful convention is to make the successor of a +blank field the types minimum value, and its predecessor the maximum. +</BODY> +</HTML> |