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<H1 class="no-header">resizeterm 3x 2024-03-16 ncurses 6.5 Library calls</H1>
<PRE>
<STRONG><A HREF="resizeterm.3x.html">resizeterm(3x)</A></STRONG> Library calls <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> - manage the terminal
dimensions understood by <EM>curses</EM>
</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> <EM>lines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>columns</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>resize_term(int</STRONG> <EM>lines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>columns</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>resizeterm(int</STRONG> <EM>lines</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>columns</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
This is an extension to the <EM>curses</EM> library. It provides callers with a
hook into the <EM>ncurses</EM> data to resize windows, primarily for use by
programs running in an X Window terminal (e.g., xterm) when the
terminal's screen size is changed by the user:
<STRONG>o</STRONG> <EM>curses</EM> windows cannot extend outside the screen. If the terminal
is shrunk, <EM>curses</EM> windows must be shrunk to fit.
<STRONG>o</STRONG> If the terminal is stretched, rows and/or columns can be added to
existing windows. The added cells should match the current
attributes of the windows.
If the calling program has not set up a handler for <STRONG>SIGWINCH</STRONG> when it
initializes <EM>ncurses</EM> (e.g., using <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG> or <STRONG><A HREF="curs_initscr.3x.html">newterm(3x)</A></STRONG>), then
<EM>ncurses</EM> sets a handler for <STRONG>SIGWINCH</STRONG> which notifies the library when a
window-size event has occurred. The library checks for this
notification
<STRONG>o</STRONG> when reading input data,
<STRONG>o</STRONG> when implicitly resuming program mode (e.g., between <STRONG><A HREF="curs_initscr.3x.html">endwin(3x)</A></STRONG> and
<STRONG><A HREF="curs_refresh.3x.html">wrefresh(3x)</A></STRONG>), and
<STRONG>o</STRONG> when explicitly resuming program mode in <STRONG><A HREF="curs_terminfo.3x.html">restartterm(3x)</A></STRONG>.
When the library has found that the terminal's window-size has changed,
it calls <STRONG>resizeterm</STRONG> to update its data structures.
An application which establishes its own <STRONG>SIGWINCH</STRONG> handler can call
<STRONG>resizeterm</STRONG>, but in that case, the library will not see <STRONG>SIGWINCH</STRONG>, and
proper layout will rely upon the application.
</PRE><H2><a name="h2-FUNCTIONS">FUNCTIONS</a></H2><PRE>
</PRE><H3><a name="h3-resizeterm">resizeterm</a></H3><PRE>
The function <STRONG>resizeterm</STRONG> resizes the standard and current windows (i.e.,
<STRONG>stdscr</STRONG> and <STRONG>curscr</STRONG>) to the specified dimensions, and adjusts other
bookkeeping data used by the <EM>ncurses</EM> 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 for <STRONG>resizeterm</STRONG> 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="curs_slk.3x.html">slk_touch(3x)</A></STRONG>).
The <STRONG>resize_term</STRONG> function attempts to resize all windows. This helps
with simple applications. However:
<STRONG>o</STRONG> It is not possible to automatically resize pads.
<STRONG>o</STRONG> Applications which have complicated layouts should check for
<STRONG>KEY_RESIZE</STRONG> returned from <STRONG>wgetch</STRONG>, and adjust their layout, e.g.,
using <STRONG>wresize</STRONG> and <STRONG>mvwin</STRONG>, or by recreating the windows.
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
memory 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
handler (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 <EM>ncurses</EM> 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>, <STRONG><A HREF="curs_refresh.3x.html">doupdate(3x)</A></STRONG> and <STRONG><A HREF="curs_terminfo.3x.html">restartterm(3x)</A></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 <EM>ncurses</EM> data structures.
If the environment variables <EM>LINES</EM> or <EM>COLUMNS</EM> are set, this overrides
the library's use of the window size obtained from the operating
system. 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 <EM>curses</EM>, by
<STRONG>o</STRONG> exiting <EM>curses</EM> 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 <EM>ncurses</EM> was introduced in mid-1995. It was adopted
in NetBSD <EM>curses</EM> (2001) and PDCurses (2003).
</PRE><H2><a name="h2-AUTHORS">AUTHORS</a></H2><PRE>
Thomas Dickey (from an equivalent function written in 1988 for BSD
<EM>curses</EM>)
</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>
ncurses 6.5 2024-03-16 <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></li>
<li><a href="#h2-FUNCTIONS">FUNCTIONS</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-AUTHORS">AUTHORS</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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