curs_touch.3

.\" $OpenBSD: src/lib/libcurses/curs_touch.3,v 1.7 2010/01/12 23:21:59 nicm Exp $
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.\" $Id: curs_touch.3x,v 1.11 2006/02/25 21:49:19 tom Exp $
.TH curs_touch 3 ""
.na
.hy 0
.SH NAME
\fBtouchwin\fR,
\fBtouchline\fR,
\fBuntouchwin\fR,
\fBwtouchln\fR,
\fBis_linetouched\fR,
\fBis_wintouched\fR - \fBcurses\fR refresh control routines
.ad
.hy
.SH SYNOPSIS
\fB#include <curses.h>\fR
.br
\fBint touchwin(WINDOW *win);\fR
.br
\fBint touchline(WINDOW *win, int start, int count);\fR
.br
\fBint untouchwin(WINDOW *win);\fR
.br
\fBint wtouchln(WINDOW *win, int y, int n, int changed);\fR
.br
\fBbool is_linetouched(WINDOW *win, int line);\fR
.br
\fBbool is_wintouched(WINDOW *win);\fR
.br
.SH DESCRIPTION
The \fBtouchwin\fR and \fBtouchline\fR routines throw away all
optimization information about which parts of the window have been
touched, by pretending that the entire window has been drawn on.  This
is sometimes necessary when using overlapping windows, since a change
to one window affects the other window, but the records of which lines
have been changed in the other window do not reflect the change.  The
routine \fBtouchline\fR only pretends that \fIcount\fR lines have been
changed, beginning with line \fIstart\fR.
.PP
The \fBuntouchwin\fR routine marks all lines in the window as unchanged since
the last call to \fBwrefresh\fR.
.PP
The \fBwtouchln\fR routine makes \fIn\fR lines in the window, starting
at line \fIy\fR, look as if they have (\fIchanged\fR\fB=1\fR) or have
not (\fIchanged\fR\fB=0\fR) been changed since the last call to
\fBwrefresh\fR.
.PP
The \fBis_linetouched\fR and \fBis_wintouched\fR routines return
\fBTRUE\fR if the specified line/window was modified since the last
call to \fBwrefresh\fR; otherwise they return \fBFALSE\fR.  In
addition, \fBis_linetouched\fR returns \fBERR\fR if \fIline\fR is not
valid for the given window.
.SH RETURN VALUE
All routines return the integer \fBERR\fR upon failure and an integer value
other than \fBERR\fR upon successful completion, unless otherwise noted in the
preceding routine descriptions.
.PP
X/Open does not define any error conditions.
In this implementation
.RS
.TP 5
\fBis_linetouched\fP
returns an error 
if the window pointer is null, or
if the line number is outside the window.
Note that ERR is distinct from TRUE and FALSE, which are the normal return values of this function.
.TP 5
\fBwtouchln\fP
returns an error 
if the window pointer is null, or
if the line number is outside the window.
.RE
.SH PORTABILITY
The XSI Curses standard, Issue 4 describes these functions.
.PP
Some historic curses implementations had, as an undocumented feature, the
ability to do the equivalent of \fBclearok(..., 1)\fR by saying
\fBtouchwin(stdscr)\fR or \fBclear(stdscr)\fR.  This will not work under
ncurses.
.SH NOTES
Note that all routines except \fBwtouchln\fR may be macros.
.SH SEE ALSO
\fBcurses\fR(3), \fBcurs_refresh\fR(3).
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