ncurses-5.7/man/resizeterm.3x

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.\" Author: Thomas E. Dickey 1996-2005
.\"
.\" $Id: resizeterm.3x,v 1.11 2005/06/25 22:19:42 tom Exp $
.TH resizeterm 3X ""
.SH NAME
\fBis_term_resized\fR,
\fBresize_term\fR,
\fBresizeterm\fR - change the curses terminal size
.SH SYNOPSIS
\fB#include <curses.h>\fR
.sp
\fBbool is_term_resized(int lines, int columns);\fR
.br
\fBint resize_term(int lines, int columns);\fR
.br
\fBint resizeterm(int lines, int columns);\fR
.SH DESCRIPTION
This is an extension to the curses library.
It provides callers with a hook into the \fBncurses\fR data to resize windows,
primarily for use by programs running in an X Window terminal (e.g., xterm).
The function \fBresizeterm\fR resizes the standard and current windows
to the specified dimensions, and adjusts other bookkeeping data used by
the \fBncurses\fR library that record the window dimensions.
.LP
Most of the work is done by the inner function \fBresize_term\fR.
The outer function \fBresizeterm\fR adds bookkeeping for the SIGWINCH handler.
When resizing the windows,
\fBresize_term\fR blank-fills the areas that are extended.
The calling application should fill in these areas with appropriate data.
The \fBresize_term\fR 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.
.LP
A support function \fBis_term_resized\fR is provided so that applications
can check if the \fBresize_term\fR function would modify the window structures.
It returns TRUE if the windows would be modified, and FALSE otherwise.
.SH RETURN VALUE
Except as notes, these function return
the integer \fBERR\fR upon failure and \fBOK\fR 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.
.SH NOTES
While these functions are intended to be used to support a signal handler
(i.e., for SIGWINCH), care should be taken to avoid invoking them in a
context where \fBmalloc\fR or \fBrealloc\fR may have been interrupted,
since it uses those functions.
.PP
If ncurses is configured to supply its own SIGWINCH handler,
the \fBresizeterm\fR function ungetch's a \fBKEY_RESIZE\fR which
will be read on the next call to \fBgetch\fR.
This is used to alert an application that the screen size has changed,
and that it should repaint special features such as pads that cannot
be done automatically.
.PP
If the environment variables \fBLINES\fP or \fBCOLUMNS\fP are set,
this overrides the library's use of the window size obtained from
the operating system.
Thus, even if a SIGWINCH is received,
no screen size change may be recorded.
In that case, no \fBKEY_RESIZE\fP is queued for the next call to \fBgetch\fP;
an \fBERR\fP will be returned instead.
.SH SEE ALSO
\fBwresize\fR(3X).
.SH AUTHOR
Thomas Dickey (from an equivalent function written in 1988 for BSD curses).
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