ncurses 6.0 - patch 20170527

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

diff --git a/man/resizeterm.3x b/man/resizeterm.3x
index 9c7cc8fd3873f011538371453d40bdb152600024..9ab3b011a1058d27e8f9ade583bc2a20f4c3a57d 100644 (file)
--- a/man/resizeterm.3x
+++ b/man/resizeterm.3x
@@ -1,5 +1,5 @@
 .\"***************************************************************************
 .\"***************************************************************************

-.\" Copyright (c) 1998 Free Software Foundation, Inc.                        *
+.\" Copyright (c) 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            *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *


@@ -26,62 +26,104 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"

-.\" Author: Thomas E. Dickey <dickey@clark.net> 1996,1997
+.\" Author: Thomas E. Dickey 1996-on

 .\"
 .\"

-.\" $Id: resizeterm.3x,v 1.7 1998/03/14 23:42:52 tom Exp $
+.\" $Id: resizeterm.3x,v 1.22 2017/01/07 19:25:15 tom Exp $

 .TH resizeterm 3X ""
 .TH resizeterm 3X ""

-.SH NAME
-\fBresizeterm\fR - change the curses terminal size
+.de bP
+.IP \(bu 4

 ..
 ..

+.SH NAME
+\fBis_term_resized\fR,
+\fBresize_term\fR,
+\fBresizeterm\fR \- change the curses terminal size

 .SH SYNOPSIS
 \fB#include <curses.h>\fR
 .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
 \fBint resizeterm(int lines, int columns);\fR

-..

 .SH DESCRIPTION
 .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).
 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 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.
 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
 .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
 .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.
 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,
 .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(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.
 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
 .SH SEE ALSO

+\fBcurs_getch\fR(3X),
+\fBcurs_variables\fR(3X),

 \fBwresize\fR(3X).
 \fBwresize\fR(3X).

-..

 .SH AUTHOR
 Thomas Dickey (from an equivalent function written in 1988 for BSD curses).
 .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: