.\"***************************************************************************
-.\" Copyright (c) 1998 Free Software Foundation, Inc. *
+.\" Copyright (c) 1998-2013,2015 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 *
.\" authorization. *
.\"***************************************************************************
.\"
-.\" Author: Thomas E. Dickey <dickey@clark.net> 1996,1997
+.\" Author: Thomas E. Dickey 1996-on
.\"
-.\" $Id: resizeterm.3x,v 1.6 1998/02/11 12:13:48 tom Exp $
+.\" $Id: resizeterm.3x,v 1.21 2015/09/26 19:55:32 tom Exp $
.TH resizeterm 3X ""
-.
+.de bP
+.IP \(bu 4
+..
.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
-
+.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
+.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 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.
-.
+.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 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,
+.bP
+on receipt of a SIGWINCH, the handler sets a flag
+.bP
+which is tested in \fBwgetch\fP 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 SIGWINCH 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
+\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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