ncurses 6.5 - patch 20240504

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

diff --git a/man/resizeterm.3x b/man/resizeterm.3x
index ba5ac9836e098b865013bd3fca33602f37bcd127..5e23d9fb37bb91123e4c2967f92d61536114986e 100644 (file)
--- a/man/resizeterm.3x
+++ b/man/resizeterm.3x
@@ -1,5 +1,6 @@
 .\"***************************************************************************
 .\"***************************************************************************

-.\" Copyright (c) 1998 Free Software Foundation, Inc.                        *
+.\" Copyright 2018-2023,2024 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            *
 .\"                                                                          *
 .\" Permission is hereby granted, free of charge, to any person obtaining a  *
 .\" copy of this software and associated documentation files (the            *


@@ -26,63 +27,154 @@
 .\" authorization.                                                           *
 .\"***************************************************************************
 .\"
 .\" 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 $
-.TH resizeterm 3X ""
-.
+.\" $Id: resizeterm.3x,v 1.56 2024/03/16 15:35:01 tom Exp $
+.TH resizeterm 3X 2024-03-16 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
+.de bP
+.ie n  .IP \(bu 4
+.el    .IP \(bu 2
+..

 .SH NAME
 .SH NAME

-\fBresizeterm\fR - change the curses terminal size
-.
+\fB\%is_term_resized\fP,
+\fB\%resize_term\fP,
+\fB\%resizeterm\fP \-
+manage the terminal dimensions understood by \fIcurses\fR

 .SH SYNOPSIS
 .SH SYNOPSIS

-\fB#include <curses.h>\fR
-
-\fBint resizeterm(int lines, int columns);\fR
-.
+.nf
+\fB#include <curses.h>
+.PP
+\fBbool is_term_resized(int \fIlines\fP, int \fIcolumns\fP);
+\fBint resize_term(int \fIlines\fP, int \fIcolumns\fP);
+\fBint resizeterm(int \fIlines\fP, int \fIcolumns\fP);
+.fi

 .SH DESCRIPTION
 .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
+This is an extension to the \fIcurses\fP library.
+It provides callers with a hook into the \fI\%ncurses\fP data to resize
+windows,
+primarily for use by programs running in an X Window terminal (e.g., xterm)
+when the terminal's screen size is changed by the user:
+.bP
+\fIcurses\fP windows cannot extend outside the screen.
+If the terminal is shrunk, \fIcurses\fP windows must be shrunk to fit.
+.bP
+If the terminal is stretched,
+rows and/or columns can be added to existing windows.
+The added cells should match the current attributes of the windows.
+.PP
+If the calling program has not set up a handler for \fB\%SIGWINCH\fP
+when it initializes \fI\%ncurses\fP
+(e.g., using \fB\%initscr\fP(3X) or \fB\%newterm\fP(3X)),
+then \fI\%ncurses\fP sets a handler for \fB\%SIGWINCH\fP which notifies
+the library when a window-size event has occurred.
+The library checks for this notification
+.bP
+when reading input data,
+.bP
+when implicitly resuming program mode
+(e.g., between \fB\%endwin\fP(3X) and \fB\%wrefresh\fP(3X)),
+and
+.bP
+when explicitly resuming program mode in \fB\%restartterm\fP(3X).
+.PP
+When the library has found that the terminal's window-size has
+changed, it calls \fB\%resizeterm\fP to update its data structures.
+.PP
+An application which establishes its own \fB\%SIGWINCH\fP handler
+can call \fB\%resizeterm\fP, but in that case, the library will not
+see \fB\%SIGWINCH\fP, and proper layout will rely upon the application.
+.SH FUNCTIONS
+.SS resizeterm
+The function \fB\%resizeterm\fP resizes the standard and current windows
+(i.e., \fB\%stdscr\fP and \fB\%curscr\fP)

 to the specified dimensions, and adjusts other bookkeeping data used by
 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.
-However, due to the calling convention of pads,
-it is not possible to resize these
-without additional interaction with the application.
-.
+the \fI\%ncurses\fP library that record the window dimensions
+such as the \fB\%LINES\fP and \fB\%COLS\fP variables.
+.SS resize_term
+Most of the work for \fB\%resizeterm\fP is
+done by the inner function \fB\%resize_term\fP.
+The outer function \fB\%resizeterm\fP adds bookkeeping
+for the \fB\%SIGWINCH\fP handler,
+as well as repainting the soft-key area (see \fB\%slk_touch\fP(3X)).
+.PP
+The \fB\%resize_term\fP function attempts to resize all windows.
+This helps with simple applications.
+However:
+.bP
+It is not possible to automatically resize pads.
+.bP
+Applications which have complicated layouts should check for
+\fB\%KEY_RESIZE\fP returned from \fB\%wgetch\fP,
+and adjust their layout, e.g., using \fB\%wresize\fP and \fB\%mvwin\fP,
+or by recreating the windows.
+.PP
+When resizing windows, \fB\%resize_term\fP 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, \fB\%resize_term\fP will keep the window
+extending to the corresponding limit, regardless of whether the
+screen has shrunk or grown.
+.SS is_term_resized
+A support function \fB\%is_term_resized\fP is provided so that applications
+can check if the \fB\%resize_term\fP 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\fP upon failure and \fBOK\fP 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
-context where \fBmalloc\fR or \fBrealloc\fR may have been interrupted,
+While these functions are intended to be used to support a signal handler
+(i.e., for \fB\%SIGWINCH\fP), care should be taken to avoid invoking them in a
+context where \fB\%malloc\fP or \fB\%realloc\fP may have been interrupted,

 since it uses those functions.
 since it uses those functions.

-.

 .PP
 .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,
+If \fI\%ncurses\fP is configured to supply its own \fB\%SIGWINCH\fP
+handler,
+.bP
+on receipt of a \fB\%SIGWINCH\fP, the handler sets a flag
+.bP
+which is tested in
+\fB\%wgetch\fP(3X),
+\fB\%doupdate\fP(3X) and
+\fB\%restartterm\fP(3X),
+.bP
+in turn, calling the \fB\%resizeterm\fP function,
+.bP
+which \fB\%ungetch\fP's a \fB\%KEY_RESIZE\fP which
+will be read on the next call to \fB\%wgetch\fP.
+.IP
+The \fB\%KEY_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 \fB\%resizeterm\fP or \fB\%resize_term\fP
+directly from a signal handler is unsafe.
+This indirect method is used to provide a safe way to resize the
+\fI\%ncurses\fP data structures.
+.PP
+If the environment variables \fILINES\fP or \fI\%COLUMNS\fP are set,
+this overrides the library's use of the window size obtained from
+the operating system.
+Thus, even if a \fB\%SIGWINCH\fP is received,
+no screen size change may be recorded.
+.SH PORTABILITY
+It is possible to resize the screen with SVr4 \fIcurses\fP,
+by
+.bP
+exiting \fIcurses\fP with \fB\%endwin\fP(3X) and
+.bP
+resuming using \fB\%refresh\fP(3X).
+.PP
+Doing that clears the screen and is visually distracting.
+.PP
+This extension of \fI\%ncurses\fP was introduced in mid-1995.
+It was adopted in NetBSD \fIcurses\fP (2001) and PDCurses (2003).
+.SH AUTHORS
+Thomas Dickey (from an equivalent function written in 1988 for BSD \fIcurses\fP)

 .SH SEE ALSO
 .SH SEE ALSO

-\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:
+\fB\%curs_getch\fP(3X),
+\fB\%curs_variables\fP(3X),
+\fB\%wresize\fP(3X)