164 lines
6.6 KiB
Plaintext
164 lines
6.6 KiB
Plaintext
.\"***************************************************************************
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.\" Copyright 2018-2019,2020 Thomas E. Dickey *
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.\" Copyright 1998-2010,2016 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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.\" $Id: curs_refresh.3x,v 1.22 2020/10/24 09:43:49 tom Exp $
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.TH curs_refresh 3X ""
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.ie \n(.g .ds `` \(lq
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.el .ds `` ``
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.ie \n(.g .ds '' \(rq
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.el .ds '' ''
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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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.na
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.hy 0
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.SH NAME
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\fBdoupdate\fR,
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\fBredrawwin\fR,
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\fBrefresh\fR,
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\fBwnoutrefresh\fR,
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\fBwredrawln\fR,
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\fBwrefresh\fR \- refresh \fBcurses\fR windows and lines
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.ad
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.hy
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.SH SYNOPSIS
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\fB#include <curses.h>\fR
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.sp
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\fBint refresh(void);\fR
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.br
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\fBint wrefresh(WINDOW *\fP\fIwin\fP\fB);\fR
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.br
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\fBint wnoutrefresh(WINDOW *\fP\fIwin\fP\fB);\fR
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.br
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\fBint doupdate(void);\fR
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.sp
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\fBint redrawwin(WINDOW *\fP\fIwin\fP\fB);\fR
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.br
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\fBint wredrawln(WINDOW *\fP\fIwin\fP\fB, int \fP\fIbeg_line\fP\fB, int \fP\fInum_lines\fP\fB);\fR
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.br
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.SH DESCRIPTION
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.SS refresh/wrefresh
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The \fBrefresh\fR and \fBwrefresh\fR routines (or \fBwnoutrefresh\fR and
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\fBdoupdate\fR) must be called to get actual output to the terminal,
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as other routines merely manipulate data structures.
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The routine \fBwrefresh\fR copies
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the named window to the \fIphysical screen\fP,
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taking into account what is already there to do optimizations.
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The \fBrefresh\fR routine is the
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same, using \fBstdscr\fR as the default window.
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Unless \fBleaveok\fR has been
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enabled, the physical cursor of the terminal is left at the location of the
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cursor for that window.
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.SS wnoutrefresh/doupdate
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.PP
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The \fBwnoutrefresh\fR and \fBdoupdate\fR routines allow multiple updates with
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more efficiency than \fBwrefresh\fR alone.
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In addition to all the window
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structures, \fBcurses\fR keeps two data structures representing the terminal
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screen:
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.bP
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a \fIphysical screen\fP, describing what is actually on the screen, and
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.bP
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a \fIvirtual screen\fP, describing what the programmer wants to have on the screen.
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.PP
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The routine \fBwrefresh\fR works by
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.bP
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first calling \fBwnoutrefresh\fR,
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which copies the named window to the \fIvirtual screen\fP, and
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.bP
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then calling \fBdoupdate\fR, which compares
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the \fIvirtual screen\fP to the \fIphysical screen\fP
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and does the actual update.
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.PP
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If the programmer wishes to output several windows at once, a series
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of calls to \fBwrefresh\fR results in alternating calls to \fBwnoutrefresh\fR
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and \fBdoupdate\fR, causing several bursts of output to the screen.
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By first
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calling \fBwnoutrefresh\fR for each window, it is then possible to call
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\fBdoupdate\fR once, resulting in only one burst of output, with fewer total
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characters transmitted and less CPU time used.
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.PP
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If the \fIwin\fR argument to
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\fBwrefresh\fR is the \fIphysical screen\fP
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(i.e., the global variable \fBcurscr\fR),
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the screen is immediately cleared and repainted from scratch.
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.PP
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The phrase \*(``copies the named window
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to the virtual screen\*('' above is ambiguous.
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What actually happens is that all \fItouched\fR (changed) lines in the window
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are copied to the virtual screen.
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This affects programs that use overlapping
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windows; it means that if two windows overlap, you can refresh them in either
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order and the overlap region will be modified only when it is explicitly
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changed.
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(But see the section on \fBPORTABILITY\fR below for a warning about
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exploiting this behavior.)
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.SS wredrawln/redrawwin
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.PP
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The \fBwredrawln\fR routine indicates to \fBcurses\fR that some screen lines
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are corrupted and should be thrown away before anything is written over them.
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It touches the indicated lines (marking them changed).
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The routine \fBredrawwin\fR touches the entire window.
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.SH RETURN VALUE
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Routines that return an integer return \fBERR\fR upon failure, and \fBOK\fR
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(SVr4 only specifies "an integer value other than \fBERR\fR") upon successful
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completion.
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.PP
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X/Open does not define any error conditions.
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In this implementation
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.RS 3
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.TP 5
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\fBwnoutrefresh\fP
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returns an error
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if the window pointer is null, or
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if the window is really a pad.
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.TP 5
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\fBwredrawln\fP
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returns an error
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if the associated call to \fBtouchln\fP returns an error.
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.RE
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.SH NOTES
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Note that \fBrefresh\fR and \fBredrawwin\fR may be macros.
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.SH PORTABILITY
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The XSI Curses standard, Issue 4 describes these functions.
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.PP
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Whether \fBwnoutrefresh\fR copies to the virtual screen the entire contents
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of a window or just its changed portions has never been well-documented in
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historic curses versions (including SVr4).
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It might be unwise to rely on
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either behavior in programs that might have to be linked with other curses
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implementations.
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Instead, you can do an explicit \fBtouchwin\fR before the
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\fBwnoutrefresh\fR call to guarantee an entire-contents copy anywhere.
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.SH SEE ALSO
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\fBcurses\fR(3X),
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\fBcurs_outopts\fR(3X)
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\fBcurs_variables\fR(3X).
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