ncurses/man/curs_touch.3x

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.\" $Id: curs_touch.3x,v 1.63 2025/01/19 00:51:10 tom Exp $
.TH curs_touch 3X 2025-01-18 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "Library calls"
.ie \n(.g \{\
.ds `` \(lq
.ds '' \(rq
.\}
.el \{\
.ie t .ds `` ``
.el   .ds `` ""
.ie t .ds '' ''
.el   .ds '' ""
.\}
.SH NAME
\fB\%touchwin\fP,
\fB\%touchline\fP,
\fB\%untouchwin\fP,
\fB\%wtouchln\fP,
\fB\%is_linetouched\fP,
\fB\%is_wintouched\fP \-
control terminal output refresh in a \fIcurses\fR window
.SH SYNOPSIS
.nf
\fB#include <curses.h>
.PP
\fBint touchline(WINDOW *\fIwin\fP, int \fIstart\fP, int \fIcount\fP);
.PP
\fBint touchwin(WINDOW *\fIwin\fP);
\fBint wtouchln(WINDOW *\fIwin\fP, int \fIy\fP, int \fIn\fP, int \fIchanged\fP);
.PP
\fBint untouchwin(WINDOW *\fIwin\fP);
.PP
\fBbool is_linetouched(WINDOW *\fIwin\fP, int \fIline\fP);
\fBbool is_wintouched(WINDOW *\fIwin\fP);
.fi
.SH DESCRIPTION
The \fB\%touchwin\fP and \fB\%touchline\fP 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 \fB\%touchline\fP only pretends that \fIcount\fP lines have been
changed, beginning with line \fIstart\fP.
.PP
The \fB\%untouchwin\fP routine marks all lines in the window as unchanged since
the last call to \fB\%wrefresh\fP.
.PP
The \fB\%wtouchln\fP routine makes \fIn\fP lines in the window, starting
at line \fIy\fR, look as if they have (\fIchanged\fB=1\fR) or have
not (\fIchanged\fB=0\fR) been changed since the last call to
\fB\%wrefresh\fP.
.PP
The \fB\%is_linetouched\fP and \fB\%is_wintouched\fP routines return
\fBTRUE\fP if the specified line/window was modified since the last
call to \fB\%wrefresh\fP; otherwise they return \fBFALSE\fP.  In
addition, \fB\%is_linetouched\fP returns \fBERR\fP if \fIline\fP is not
valid for the given window.
.SH RETURN VALUE
Functions returning integers return
.B ERR
upon failure and
.B OK
upon success.
.PP
In
.IR \%ncurses ","
.RS 3
.TP 5
\fBis_linetouched\fP
returns
.B ERR
if the window pointer is null, or
if the line number is outside the window boundaries.
.IP
The constant \fBERR\fP is distinct from \fBTRUE\fP and \fBFALSE\fP,
which are the normal return values of this function.
Because the function returns a \fBbool\fP,
returning \fBERR\fP (which is neither \fBTRUE\fP nor \fBFALSE\fP)
may not be supported by the compiler.
.IP
To provide error-checking and also match the X/Open function prototype,
the \fBERR\fP is provided by a macro named \fB\%is_linetouched\fP.
The actual function returns \fBFALSE\fP when it detects an error.
.TP 5
\fBwtouchln\fP
returns
.B ERR
if the window pointer is null, or
if the line number is outside the window boundaries.
.RE
.SH NOTES
All of these functions except
.B \%wtouchln
may be implemented as macros.
.SH PORTABILITY
X/Open Curses Issue\ 4 describes these functions.
It specifies no error conditions for them.
.PP
SVr4 describes a successful return value
except where \*(``otherwise noted\*(''
as
\*(``an integer value other than
.IR ERR \*(''. \" Courier roman in source; SVID 4, vol. 3, p. 540
.PP
SVr4 does not check
.I win
to ensure that it is not a null pointer.
.SH HISTORY
SVr2 (1984) introduced
.IR \%touchwin ","
.PP
SVr3 (1987) added
.IR \%touchline "."
SVr3.1 later that year supplied
.IR \%is_linetouched ","
.IR \%is_wintouched ","
.IR \%untouchwin ","
and
.IR \%wtouchln "."
.SH SEE ALSO
\fB\%curses\fP(3X),
\fB\%curs_refresh\fP(3X),
\fB\%curs_variables\fP(3X)