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.\" Copyright 2018-2019,2020 Thomas E. Dickey *
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.\" $Id: curs_scroll.3x,v 1.18 2020/02/02 23:34:34 tom Exp $
.TH curs_scroll 3X ""
.ie \n(.g .ds `` \(lq
.el .ds `` ``
.ie \n(.g .ds '' \(rq
.el .ds '' ''
.na
.hy 0
.SH NAME
\fBscroll\fR,
\fBscrl\fR,
\fBwscrl\fR \- scroll a \fBcurses\fR window
.ad
.hy
.SH SYNOPSIS
\fB#include <curses.h>\fR
.sp
\fBint scroll(WINDOW *win);\fR
.br
\fBint scrl(int n);\fR
.br
\fBint wscrl(WINDOW *win, int n);\fR
.br
.SH DESCRIPTION
The \fBscroll\fR routine scrolls the window up one line.
This involves moving
the lines in the window data structure.
As an optimization, if the scrolling
region of the window is the entire screen,
the \fIphysical screen\fP may be scrolled at the same time.
.PP
For positive \fIn\fR, the \fBscrl\fR and \fBwscrl\fR routines scroll the
window up \fIn\fR lines (line \fIi\fR+\fIn\fR becomes \fIi\fR); otherwise
scroll the window down \fIn\fR lines.
This involves moving the lines in the
window character image structure.
The current cursor position is not changed.
.PP
For these functions to work, scrolling must be enabled via \fBscrollok\fR.
.SH RETURN VALUE
These routines return \fBERR\fR upon failure, and \fBOK\fR (SVr4 only specifies
"an integer value other than \fBERR\fR") upon successful completion.
.PP
X/Open defines no error conditions.
.PP
This implementation returns an error
if the window pointer is null, or
if scrolling is not enabled in the window, e.g., with \fBscrollok\fP.
.SH NOTES
Note that \fBscrl\fR and \fBscroll\fR may be macros.
.PP
The SVr4 documentation says that the optimization of physically scrolling
immediately if the scroll region is the entire screen \*(``is\*('' performed, not
\*(``may be\*('' performed.
This implementation deliberately does not guarantee
that this will occur, to leave open the possibility of smarter
optimization of multiple scroll actions on the next update.
.PP
Neither the SVr4 nor the XSI documentation specify whether the current
attribute or
current color-pair of blanks generated by the scroll function is zeroed.
Under this implementation it is.
.SH PORTABILITY
The XSI Curses standard, Issue 4 describes these functions.
.SH SEE ALSO
\fBcurses\fR(3X), \fBcurs_outopts\fR(3X)