145 lines
6.3 KiB
Plaintext
145 lines
6.3 KiB
Plaintext
.\"***************************************************************************
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.\" Copyright (c) 1998-2001,2005 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 1.12 2005/05/15 16:18:49 tom Exp $
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.TH curs_refresh 3X ""
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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 *win);\fR
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.br
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\fBint wnoutrefresh(WINDOW *win);\fR
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.br
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\fBint doupdate(void);\fR
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.br
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\fBint redrawwin(WINDOW *win);\fR
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.br
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\fBint wredrawln(WINDOW *win, int beg_line, int num_lines);\fR
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.br
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.SH DESCRIPTION
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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, as other
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routines merely manipulate data structures.
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The routine \fBwrefresh\fR copies
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the named window to the physical terminal screen, taking into account what is
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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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.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: a physical screen, describing what is actually on the screen, and a
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virtual screen, 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 first calling \fBwnoutrefresh\fR, which
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copies the named window to the virtual screen, and then calling \fBdoupdate\fR,
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which compares the virtual screen to the physical screen and does the actual
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update.
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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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If the \fIwin\fR argument to
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\fBwrefresh\fR is the global variable \fBcurscr\fR, the screen is immediately
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cleared and repainted from scratch.
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.PP
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The phrase "copies the named window 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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.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
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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), \fBcurs_outopts\fR(3X)
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.\"#
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.\"# The following sets edit modes for GNU EMACS
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.\"# Local Variables:
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.\"# mode:nroff
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.\"# fill-column:79
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.\"# End:
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