ncurses 6.0 - patch 20150926

[ncurses.git] / man / resizeterm.3x

diff --git a/man/resizeterm.3x b/man/resizeterm.3x
index 888eaaf318d1dbf7e3ed2c4797ebd29d87d23e31..b88f68f351ff23a059271aaba3e97248e894cadd 100644 (file)
--- a/man/resizeterm.3x
+++ b/man/resizeterm.3x
@@ -1,5 +1,5 @@
 .\"***************************************************************************
-.\" Copyright (c) 1998-2003,2005 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            *
@@ -26,14 +26,17 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
-.\" Author: Thomas E. Dickey 1996-2005
+.\" Author: Thomas E. Dickey 1996-on
 .\"
-.\" $Id: resizeterm.3x,v 1.11 2005/06/25 22:19:42 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
 \fBis_term_resized\fR,
 \fBresize_term\fR,
-\fBresizeterm\fR - change the curses terminal size
+\fBresizeterm\fR \- change the curses terminal size
 .SH SYNOPSIS
 \fB#include <curses.h>\fR
 .sp
@@ -43,13 +46,18 @@
 .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.
-.LP
+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,
@@ -59,12 +67,13 @@ 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
+.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 TRUE if the windows would be modified, and FALSE otherwise.
+It returns \fBTRUE\fP if the windows would be modified, and \fBFALSE\fP otherwise.
 .SH RETURN VALUE
-Except as notes, these function return
+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.
@@ -75,26 +84,46 @@ 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.
-In that case, no \fBKEY_RESIZE\fP is queued for the next call to \fBgetch\fP;
-an \fBERR\fP will be returned instead.
+.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: