143 lines
6.1 KiB
Plaintext
143 lines
6.1 KiB
Plaintext
.\"***************************************************************************
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.\" Copyright (c) 1998-2018,2019 Free Software Foundation, Inc. *
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.\" *
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.\" Permission is hereby granted, free of charge, to any person obtaining a *
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.\" copy of this software and associated documentation files (the *
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.\" "Software"), to deal in the Software without restriction, including *
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.\" without limitation the rights to use, copy, modify, merge, publish, *
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.\" distribute, distribute with modifications, sublicense, and/or sell *
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.\" copies of the Software, and to permit persons to whom the Software is *
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.\" furnished to do so, subject to the following conditions: *
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.\" *
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.\" The above copyright notice and this permission notice shall be included *
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.\" in all copies or substantial portions of the Software. *
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.\" *
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
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.\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
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.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
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.\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
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.\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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.\" *
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.\" Except as contained in this notice, the name(s) of the above copyright *
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.\" holders shall not be used in advertising or otherwise to promote the *
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.\" sale, use or other dealings in this Software without prior written *
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.\" authorization. *
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.\"***************************************************************************
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.\"
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.\" Author: Thomas E. Dickey 1996-on
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.\"
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.\" $Id: resizeterm.3x,v 1.26 2019/09/21 23:44:41 tom Exp $
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.TH resizeterm 3X ""
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.de bP
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.ie n .IP \(bu 4
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.el .IP \(bu 2
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..
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.SH NAME
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\fBis_term_resized\fR,
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\fBresize_term\fR,
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\fBresizeterm\fR \- change the curses terminal size
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.SH SYNOPSIS
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\fB#include <curses.h>\fR
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.sp
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\fBbool is_term_resized(int lines, int columns);\fR
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.br
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\fBint resize_term(int lines, int columns);\fR
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.br
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\fBint resizeterm(int lines, int columns);\fR
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.SH DESCRIPTION
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.PP
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This is an extension to the curses library.
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It provides callers with a hook into the \fBncurses\fR data to resize windows,
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primarily for use by programs running in an X Window terminal (e.g., xterm).
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.SS resizeterm
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.PP
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The function \fBresizeterm\fR resizes the standard and current windows
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to the specified dimensions, and adjusts other bookkeeping data used by
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the \fBncurses\fR library that record the window dimensions
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such as the \fBLINES\fP and \fBCOLS\fP variables.
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.SS resize_term
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.PP
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Most of the work is done by the inner function \fBresize_term\fR.
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The outer function \fBresizeterm\fR adds bookkeeping
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for the \fBSIGWINCH\fP handler,
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as well as repainting the soft-key area (see \fBslk_touch\fP(3X)).
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.PP
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When resizing the windows,
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\fBresize_term\fR blank-fills the areas that are extended.
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The calling application should fill in these areas with appropriate data.
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.PP
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The \fBresize_term\fR function attempts to resize all windows.
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However, due to the calling convention of pads,
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it is not possible to resize these
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without additional interaction with the application.
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.PP
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When resizing windows, \fBresize_term\fR recursively adjusts subwindows,
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keeping them within the updated parent window's limits.
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If a top-level window happens to extend to the screen's limits,
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then on resizing the window, \fBresize_term\fR will keep the window
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extending to the corresponding limit, regardless of whether the
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screen has shrunk or grown.
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.SS is_term_resized
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.PP
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A support function \fBis_term_resized\fR is provided so that applications
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can check if the \fBresize_term\fR function would modify the window structures.
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It returns \fBTRUE\fP if the windows would be modified,
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and \fBFALSE\fP otherwise.
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.SH RETURN VALUE
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Except as noted, these functions return
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the integer \fBERR\fR upon failure and \fBOK\fR on success.
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They will fail if either of the dimensions are less than or equal to zero,
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or if an error occurs while (re)allocating memory for the windows.
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.SH NOTES
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While these functions are intended to be used to support a signal handler
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(i.e., for \fBSIGWINCH\fP), care should be taken to avoid invoking them in a
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context where \fBmalloc\fR or \fBrealloc\fR may have been interrupted,
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since it uses those functions.
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.PP
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If ncurses is configured to supply its own \fBSIGWINCH\fP handler,
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.bP
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on receipt of a \fBSIGWINCH\fP, the handler sets a flag
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.bP
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which is tested in \fBwgetch\fP(3X) and \fBdoupdate\fP,
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.bP
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in turn, calling the \fBresizeterm\fR function,
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.bP
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which \fBungetch\fP's a \fBKEY_RESIZE\fR which
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will be read on the next call to \fBwgetch\fR.
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.IP
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The \fBKEY_RESIZE\fP alerts an application that the screen size has changed,
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and that it should repaint special features such as pads that cannot
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be done automatically.
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.IP
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Calling \fBresizeterm\fP or \fBresize_term\fP
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directly from a signal handler is unsafe.
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This indirect method is used to provide a safe way to resize the ncurses
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data structures.
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.PP
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If the environment variables \fBLINES\fP or \fBCOLUMNS\fP are set,
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this overrides the library's use of the window size obtained from
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the operating system.
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Thus, even if a \fBSIGWINCH\fP is received,
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no screen size change may be recorded.
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.SH PORTABILITY
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.PP
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It is possible to resize the screen with SVr4 curses,
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by
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.bP
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exiting curses with \fBendwin\fP(3X) and
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.bP
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resuming using \fBrefresh\fP(3X).
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.PP
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Doing that clears the screen and is visually distracting.
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.PP
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This extension of ncurses was introduced in mid-1995.
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It was adopted in NetBSD curses (2001) and PDCurses (2003).
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.SH SEE ALSO
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\fBcurs_getch\fR(3X),
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\fBcurs_variables\fR(3X),
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\fBwresize\fR(3X).
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.SH AUTHOR
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Thomas Dickey (from an equivalent function written in 1988 for BSD curses).
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