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* Author: Thomas E. Dickey 1996-on
* @Id: resizeterm.3x,v 1.27 2020/02/02 23:34:34 tom Exp @
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<H1 class="no-header">resizeterm 3x</H1>
<PRE>
<STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG> <STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>is_term_resized</STRONG>, <STRONG>resize_term</STRONG>, <STRONG>resizeterm</STRONG> - change the curses terminal
size
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>bool</STRONG> <STRONG>is_term_resized(int</STRONG> <STRONG>lines,</STRONG> <STRONG>int</STRONG> <STRONG>columns);</STRONG>
<STRONG>int</STRONG> <STRONG>resize_term(int</STRONG> <STRONG>lines,</STRONG> <STRONG>int</STRONG> <STRONG>columns);</STRONG>
<STRONG>int</STRONG> <STRONG>resizeterm(int</STRONG> <STRONG>lines,</STRONG> <STRONG>int</STRONG> <STRONG>columns);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
This is an extension to the curses library. It provides callers with a
hook into the <STRONG>ncurses</STRONG> data to resize windows, primarily for use by pro-
grams running in an X Window terminal (e.g., xterm).
</PRE><H3><a name="h3-resizeterm">resizeterm</a></H3><PRE>
The function <STRONG>resizeterm</STRONG> resizes the standard and current windows to the
specified dimensions, and adjusts other bookkeeping data used by the
<STRONG>ncurses</STRONG> library that record the window dimensions such as the <STRONG>LINES</STRONG> and
<STRONG>COLS</STRONG> variables.
</PRE><H3><a name="h3-resize_term">resize_term</a></H3><PRE>
Most of the work is done by the inner function <STRONG>resize_term</STRONG>. The outer
function <STRONG>resizeterm</STRONG> adds bookkeeping for the <STRONG>SIGWINCH</STRONG> handler, as well
as repainting the soft-key area (see <STRONG><A HREF="slk_touch.3x.html">slk_touch(3x)</A></STRONG>).
When resizing the windows, <STRONG>resize_term</STRONG> blank-fills the areas that are
extended. The calling application should fill in these areas with
appropriate data.
The <STRONG>resize_term</STRONG> function attempts to resize all windows. However, due
to the calling convention of pads, it is not possible to resize these
without additional interaction with the application.
When resizing windows, <STRONG>resize_term</STRONG> recursively adjusts subwindows,
keeping them within the updated parent window's limits. If a top-level
window happens to extend to the screen's limits, then on resizing the
window, <STRONG>resize_term</STRONG> will keep the window extending to the corresponding
limit, regardless of whether the screen has shrunk or grown.
</PRE><H3><a name="h3-is_term_resized">is_term_resized</a></H3><PRE>
A support function <STRONG>is_term_resized</STRONG> is provided so that applications can
check if the <STRONG>resize_term</STRONG> function would modify the window structures.
It returns <STRONG>TRUE</STRONG> if the windows would be modified, and <STRONG>FALSE</STRONG> otherwise.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
Except as noted, these functions return the integer <STRONG>ERR</STRONG> upon failure
and <STRONG>OK</STRONG> on success. They will fail if either of the dimensions are less
than or equal to zero, or if an error occurs while (re)allocating mem-
ory for the windows.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
While these functions are intended to be used to support a signal han-
dler (i.e., for <STRONG>SIGWINCH</STRONG>), care should be taken to avoid invoking them
in a context where <STRONG>malloc</STRONG> or <STRONG>realloc</STRONG> may have been interrupted, since
it uses those functions.
If ncurses is configured to supply its own <STRONG>SIGWINCH</STRONG> handler,
<STRONG>o</STRONG> on receipt of a <STRONG>SIGWINCH</STRONG>, the handler sets a flag
<STRONG>o</STRONG> which is tested in <STRONG><A HREF="curs_getch.3x.html">wgetch(3x)</A></STRONG> and <STRONG>doupdate</STRONG>,
<STRONG>o</STRONG> in turn, calling the <STRONG>resizeterm</STRONG> function,
<STRONG>o</STRONG> which <STRONG>ungetch</STRONG>'s a <STRONG>KEY_RESIZE</STRONG> which will be read on the next call to
<STRONG>wgetch</STRONG>.
The <STRONG>KEY_RESIZE</STRONG> alerts an application that the screen size has
changed, and that it should repaint special features such as pads
that cannot be done automatically.
Calling <STRONG>resizeterm</STRONG> or <STRONG>resize_term</STRONG> directly from a signal handler is
unsafe. This indirect method is used to provide a safe way to
resize the ncurses data structures.
If the environment variables <STRONG>LINES</STRONG> or <STRONG>COLUMNS</STRONG> are set, this overrides
the library's use of the window size obtained from the operating sys-
tem. Thus, even if a <STRONG>SIGWINCH</STRONG> is received, no screen size change may
be recorded.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
It is possible to resize the screen with SVr4 curses, by
<STRONG>o</STRONG> exiting curses with <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG> and
<STRONG>o</STRONG> resuming using <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG>.
Doing that clears the screen and is visually distracting.
This extension of ncurses was introduced in mid-1995. It was adopted
in NetBSD curses (2001) and PDCurses (2003).
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG><A HREF="wresize.3x.html">wresize(3x)</A></STRONG>.
</PRE><H2><a name="h2-AUTHOR">AUTHOR</a></H2><PRE>
Thomas Dickey (from an equivalent function written in 1988 for BSD
curses).
<STRONG><A HREF="resizeterm.3x.html">resizeterm(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-resizeterm">resizeterm</a></li>
<li><a href="#h3-resize_term">resize_term</a></li>
<li><a href="#h3-is_term_resized">is_term_resized</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>
<li><a href="#h2-AUTHOR">AUTHOR</a></li>
</ul>
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