-.\"*****************************************************************************
-.\" Copyright 1996 by Thomas E. Dickey <dickey@clark.net> *
-.\" All Rights Reserved. *
-.\" *
-.\" Permission to use, copy, modify, and distribute this software and its *
-.\" documentation for any purpose and without fee is hereby granted, provided *
-.\" that the above copyright notice appear in all copies and that both that *
-.\" copyright notice and this permission notice appear in supporting *
-.\" documentation, and that the name of the above listed copyright holder(s) *
-.\" not be used in advertising or publicity pertaining to distribution of the *
-.\" software without specific, written prior permission. THE ABOVE LISTED *
-.\" COPYRIGHT HOLDER(S) DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, *
-.\" INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO *
-.\" EVENT SHALL THE ABOVE LISTED COPYRIGHT HOLDER(S) BE LIABLE FOR ANY *
-.\" SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER *
-.\" RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF *
-.\" CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN *
-.\" CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
-.\"*****************************************************************************
-.\" $Id: resizeterm.3x,v 1.3 1996/12/28 20:00:50 tom Exp $
+.\"***************************************************************************
+.\" Copyright 2018-2019,2020 Thomas E. Dickey *
+.\" Copyright 1998-2015,2017 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. *
+.\"***************************************************************************
+.\"
+.\" Author: Thomas E. Dickey 1996-on
+.\"
+.\" $Id: resizeterm.3x,v 1.28 2020/10/17 23:55:41 tom Exp $
.TH resizeterm 3X ""
-.
+.de bP
+.ie n .IP \(bu 4
+.el .IP \(bu 2
+..
.SH NAME
-\fBresizeterm\fR - change the curses terminal size
-.
+\fBis_term_resized\fR,
+\fBresize_term\fR,
+\fBresizeterm\fR \- change the curses terminal size
.SH SYNOPSIS
\fB#include <curses.h>\fR
-
-\fBint resizeterm(int lines, int columns);\fR
-.
+.sp
+\fBbool is_term_resized(int \fP\fIlines\fP\fB, int \fP\fIcolumns\fP\fB);\fR
+.br
+\fBint resize_term(int \fP\fIlines\fP\fB, int \fP\fIcolumns\fP\fB);\fR
+.br
+\fBint resizeterm(int \fP\fIlines\fP\fB, int \fP\fIcolumns\fP\fB);\fR
.SH DESCRIPTION
+.PP
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).
+.SS resizeterm
+.PP
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.
-
-When resizing the windows, the function blank-fills the areas that are
-extended. The calling application should fill in these areas with
-appropriate data.
-
-The function attempts to resize all windows.
+the \fBncurses\fR library that record the window dimensions
+such as the \fBLINES\fP and \fBCOLS\fP variables.
+.SS resize_term
+.PP
+Most of the work is done by the inner function \fBresize_term\fR.
+The outer function \fBresizeterm\fR adds bookkeeping
+for the \fBSIGWINCH\fP handler,
+as well as repainting the soft-key area (see \fBslk_touch\fP(3X)).
+.PP
+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.
+.PP
+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.
-.
+.PP
+When resizing windows, \fBresize_term\fR 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, \fBresize_term\fR will keep the window
+extending to the corresponding limit, regardless of whether the
+screen has shrunk or grown.
+.SS is_term_resized
+.PP
+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 \fBTRUE\fP if the windows would be modified,
+and \fBFALSE\fP otherwise.
.SH RETURN VALUE
-The function returns the integer \fBERR\fR upon failure and \fBOK\fR on success.
-It will fail if either of the dimensions less than or equal to zero,
-or if an error occurs while (re)allocating memory for the windows.
-.
+Except as noted, these functions 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 this function is intended to be used to support a signal handler
-(i.e., for SIGWINCH), care should be taken to avoid invoking it in a
+While these functions are intended to be used to support a signal handler
+(i.e., for \fBSIGWINCH\fP), 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 \fBSIGWINCH\fP handler,
+.bP
+on receipt of a \fBSIGWINCH\fP, the handler sets a flag
+.bP
+which is tested in \fBwgetch\fP(3X) and \fBdoupdate\fP,
+.bP
+in turn, calling the \fBresizeterm\fR function,
+.bP
+which \fBungetch\fP's a \fBKEY_RESIZE\fR which
+will be read on the next call to \fBwgetch\fR.
+.IP
+The \fBKEY_RESIZE\fP alerts an application that the screen size has changed,
+and that it should repaint special features such as pads that cannot
+be done automatically.
+.IP
+Calling \fBresizeterm\fP or \fBresize_term\fP
+directly from a signal handler is unsafe.
+This indirect method is used to provide a safe way to resize the ncurses
+data structures.
+.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 \fBSIGWINCH\fP is received,
+no screen size change may be recorded.
+.SH PORTABILITY
+.PP
+It is possible to resize the screen with SVr4 curses,
+by
+.bP
+exiting curses with \fBendwin\fP(3X) and
+.bP
+resuming using \fBrefresh\fP(3X).
+.PP
+Doing that clears the screen and is visually distracting.
+.PP
+This extension of ncurses was introduced in mid-1995.
+It was adopted in NetBSD curses (2001) and PDCurses (2003).
.SH SEE ALSO
-\fBwresize\fR(3x).
-.
+\fBcurs_getch\fR(3X),
+\fBcurs_variables\fR(3X),
+\fBwresize\fR(3X).
.SH AUTHOR
Thomas Dickey (from an equivalent function written in 1988 for BSD curses).
-.\"#
-.\"# The following sets edit modes for GNU EMACS
-.\"# Local Variables:
-.\"# mode:nroff
-.\"# fill-column:79
-.\"# End:
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