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* @Id: curs_pad.3x,v 1.61 2024/04/27 17:55:43 tom Exp @
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<H1 class="no-header">curs_pad 3x 2024-04-27 ncurses 6.5 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_pad.3x.html">curs_pad(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_pad.3x.html">curs_pad(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>newpad</STRONG>, <STRONG>subpad</STRONG>, <STRONG>prefresh</STRONG>, <STRONG>pnoutrefresh</STRONG>, <STRONG>pechochar</STRONG>, <STRONG>pecho_wchar</STRONG> - create
and display <EM>curses</EM> pads
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>WINDOW</STRONG> <STRONG>*newpad(int</STRONG> <EM>nlines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>ncols</EM><STRONG>);</STRONG>
<STRONG>WINDOW</STRONG> <STRONG>*subpad(WINDOW</STRONG> <STRONG>*</STRONG><EM>parent</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>nlines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>ncols</EM><STRONG>,</STRONG>
<STRONG>int</STRONG> <EM>begin</EM><STRONG>_</STRONG><EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>begin</EM><STRONG>_</STRONG><EM>x</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>prefresh(WINDOW</STRONG> <STRONG>*</STRONG><EM>pad</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>pminrow</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>pmincol</EM><STRONG>,</STRONG>
<STRONG>int</STRONG> <EM>sminrow</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>smincol</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>smaxrow</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>smaxcol</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>pnoutrefresh(WINDOW</STRONG> <STRONG>*</STRONG><EM>pad</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>pminrow</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>pmincol</EM><STRONG>,</STRONG>
<STRONG>int</STRONG> <EM>sminrow</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>smincol</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>smaxrow</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>smaxcol</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>pechochar(WINDOW</STRONG> <STRONG>*</STRONG><EM>pad</EM><STRONG>,</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>pecho_wchar(WINDOW</STRONG> <STRONG>*</STRONG><EM>pad</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
A <EM>curses</EM> <EM>pad</EM> is like a window, except that it is not restricted by the
screen size, and is not necessarily associated with a particular part
of the screen. Pads can be used when a large window is needed, only
part of which is to be visible on the screen. Pads are not
automatically refreshed by scrolling or input-echoing operations.
Pads cannot be refreshed with <STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG>; use <STRONG>prefresh</STRONG> or
<STRONG>pnoutrefresh</STRONG> instead.
</PRE><H3><a name="h3-newpad">newpad</a></H3><PRE>
<STRONG>newpad</STRONG> creates and returns a pointer to a new pad data structure with
the given number of lines, <EM>nlines</EM>, and columns, <EM>ncols</EM>.
</PRE><H3><a name="h3-subpad">subpad</a></H3><PRE>
<STRONG>subpad</STRONG> creates and returns a pointer to a subwindow within a pad with
the given number of lines, <EM>nlines</EM>, and columns, <EM>ncols</EM>. Unlike
<STRONG><A HREF="subwin.3x.html">subwin(3x)</A></STRONG>, which uses screen coordinates, the new pad is placed at
position (<EM>begin</EM><STRONG>_</STRONG><EM>y</EM>, <EM>begin</EM><STRONG>_</STRONG><EM>x</EM>) relative to its parent. Thus, changes made
to one pad can affect both. When operating on a subpad, it is often
necessary to call <STRONG><A HREF="curs_touch.3x.html">touchwin(3x)</A></STRONG> or <STRONG><A HREF="curs_touch.3x.html">touchline(3x)</A></STRONG> on <EM>parent</EM> before
calling <STRONG>prefresh</STRONG>.
</PRE><H3><a name="h3-prefresh_pnoutrefresh">prefresh, pnoutrefresh</a></H3><PRE>
<STRONG>prefresh</STRONG> and <STRONG>pnoutrefresh</STRONG> are analogous to <STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG> and
<STRONG><A HREF="curs_refresh.3x.html">wnoutrefresh(3x)</A></STRONG> except that they operate on pads rather than windows.
They require additional parameters are needed to indicate what portions
of the pad and screen are involved.
<STRONG>o</STRONG> <EM>pminrow</EM> and <EM>pmincol</EM> specify the upper left-hand corner of a
rectangular view of the pad.
<STRONG>o</STRONG> <EM>sminrow</EM>, <EM>smincol</EM>, <EM>smaxrow</EM>, and <EM>smaxcol</EM> specify the vertices of the
rectangle to be displayed on the screen.
The lower right-hand corner of the rectangle to be displayed in the pad
is calculated from the screen coordinates, since the rectangles must be
the same size. Both rectangles must be entirely contained within their
respective structures. <EM>curses</EM> treats negative values of any of these
parameters as zero.
</PRE><H3><a name="h3-pechochar">pechochar</a></H3><PRE>
<STRONG>pechochar</STRONG> is functionally equivalent to calling <STRONG><A HREF="curs_addch.3x.html">waddch(3x)</A></STRONG> followed by
<STRONG>prefresh</STRONG>. It suggests to the <EM>curses</EM> optimizer that only a single
character is being output; a considerable performance benefit may be
thus enjoyed. The location of the character <EM>ch</EM> written to the pad is
used to populate the arguments to <STRONG>prefresh</STRONG>.
</PRE><H3><a name="h3-pecho_wchar">pecho_wchar</a></H3><PRE>
<STRONG>pecho_wchar</STRONG> is functionally equivalent to calling <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG> followed
by <STRONG>prefresh</STRONG>. It suggests to the <EM>curses</EM> optimizer that only a single
wide character is being output; a considerable performance benefit may
be thus enjoyed. The location of the character <EM>wch</EM> written to the pad
is used to populate the arguments to <STRONG>prefresh</STRONG>.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
Functions that return an integer return <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> (SVr4
specifies only "an integer value other than <STRONG>ERR</STRONG>") upon successful
completion.
Functions that return pointers return <STRONG>NULL</STRONG> on error, and set <STRONG>errno</STRONG> to
<STRONG>ENOMEM</STRONG>.
X/Open Curses does not specify any error conditions. In this
implementation
<STRONG>prefresh</STRONG> and <STRONG>pnoutrefresh</STRONG>
return an error if the window pointer is null, or if the window
is not really a pad or if the area to refresh extends off-
screen or if the minimum coordinates are greater than the
maximum.
<STRONG>pechochar</STRONG>
returns an error if the window is not really a pad, and the
associated call to <STRONG>wechochar</STRONG> returns an error.
<STRONG>pecho_wchar</STRONG>
returns an error if the window is not really a pad, and the
associated call to <STRONG>wecho_wchar</STRONG> returns an error.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
<STRONG>pechochar</STRONG> may be a macro.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
BSD <EM>curses</EM> has no <EM>pad</EM> feature.
SVr2 <EM>curses</EM> (1986) provided the <STRONG>newpad</STRONG> and related functions,
documenting them in a single line each. SVr3 (1987) provided more
extensive documentation.
The documentation does not explain the term <EM>pad</EM>. However, the Apollo
<EM>Aegis</EM> workstation operating system supported a graphical <EM>pad</EM> feature:
<STRONG>o</STRONG> These graphical pads could be much larger than the computer's
display.
<STRONG>o</STRONG> The read-only output from a command could be scrolled back to
inspect, and select text from the pad.
The two uses may be related.
X/Open Curses, Issue 4 describes these functions, without significant
change from the SVr3 documentation. It describes no error conditions.
The behavior of <STRONG>subpad</STRONG> if the parent window is not a pad is
undocumented, and is not checked by the vendor Unix implementations:
<STRONG>o</STRONG> SVr4 <EM>curses</EM> sets a flag in the <EM>WINDOW</EM> structure in <STRONG>newpad</STRONG> which
tells if the window is a <EM>pad</EM>.
However, it uses this information only in <STRONG>waddch</STRONG> (to decide if it
should call <STRONG>wrefresh</STRONG>) and <STRONG>wscrl</STRONG> (to avoid scrolling a pad), and
does not check in <STRONG>wrefresh</STRONG> to ensure that the pad is refreshed
properly.
<STRONG>o</STRONG> Solaris <EM>xcurses</EM> checks whether a window is a pad in <STRONG>wnoutrefresh</STRONG>,
returning <STRONG>ERR</STRONG> in that case.
However, it only sets the flag for subwindows if the parent window
is a pad. Its <STRONG>newpad</STRONG> function does not set this information.
Consequently, the check will never fail.
It makes no comparable check in <STRONG>pnoutrefresh</STRONG>, though interestingly
enough, a comment in the source code states that the lack of a
check was an MKS extension.
<STRONG>o</STRONG> NetBSD 7 <EM>curses</EM> sets a flag in the <EM>WINDOW</EM> structure for <STRONG>newpad</STRONG> and
<STRONG>subpad</STRONG>, using this to help with the distinction between
<STRONG>wnoutrefresh</STRONG> and <STRONG>pnoutrefresh</STRONG>.
It does not check for the case where a subwindow is created in a
pad using <STRONG>subwin</STRONG> or <STRONG>derwin</STRONG>.
The <STRONG>dupwin</STRONG> function returns a regular window when duplicating a
pad. Likewise, <STRONG>getwin</STRONG> always returns a window, even if the saved
data was from a pad.
This implementation
<STRONG>o</STRONG> sets a flag in the <EM>WINDOW</EM> structure for <STRONG>newpad</STRONG> and <STRONG>subpad</STRONG>,
<STRONG>o</STRONG> allows a <STRONG>subwin</STRONG> or <STRONG>derwin</STRONG> call to succeed having a pad parent by
forcing the subwindow to be a pad,
<STRONG>o</STRONG> checks in both <STRONG>wnoutrefresh</STRONG> and <STRONG>pnoutrefresh</STRONG> to ensure that pads
and windows are handled distinctly, and
<STRONG>o</STRONG> ensures that <STRONG>dupwin</STRONG> and <STRONG>getwin</STRONG> treat pads versus windows
consistently.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_touch.3x.html">curs_touch(3x)</A></STRONG>
ncurses 6.5 2024-04-27 <STRONG><A HREF="curs_pad.3x.html">curs_pad(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-newpad">newpad</a></li>
<li><a href="#h3-subpad">subpad</a></li>
<li><a href="#h3-prefresh_pnoutrefresh">prefresh, pnoutrefresh</a></li>
<li><a href="#h3-pechochar">pechochar</a></li>
<li><a href="#h3-pecho_wchar">pecho_wchar</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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