.\"***************************************************************************
.\" Copyright 2018,2020 Thomas E. Dickey                                     *
.\" Copyright 2002-2015,2017 Free Software Foundation, Inc.                  *
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.\"
.\" $Id: curs_bkgrnd.3x,v 1.11 2020/02/02 23:34:34 tom Exp $
.de bP
.ie n  .IP \(bu 4
.el    .IP \(bu 2
..
.TH curs_bkgrnd 3X ""
.SH NAME
\fBbkgrnd\fR,
\fBwbkgrnd\fR,
\fBbkgrndset\fR,
\fBwbkgrndset\fR,
\fBgetbkgrnd\fR,
\fBwgetbkgrnd\fR \- \fBcurses\fR window complex background manipulation routines
.SH SYNOPSIS
.PP
.B #include <curses.h>
.sp
\fBint bkgrnd(\fR\fB const cchar_t *\fR\fIwch\fR\fB);\fR
.br
\fBint wbkgrnd(\fR\fB WINDOW *\fR\fIwin\fR\fB, const cchar_t *\fR\fIwch\fR\fB);\fR
.br
\fBvoid bkgrndset(const cchar_t *\fR\fIwch\fR \fB);\fR
.br
\fBvoid wbkgrndset(WINDOW *\fR\fIwin\fR\fB, const cchar_t *\fR\fIwch\fR\fB);\fR
.br
\fBint getbkgrnd(cchar_t *\fR\fIwch\fR\fB);\fR
.br
\fBint wgetbkgrnd(WINDOW *\fR\fIwin\fR\fB, cchar_t *\fR\fIwch\fR\fB);\fR
.br
.SH DESCRIPTION
.SS bkgrndset
.PP
The \fBbkgrndset\fR and \fBwbkgrndset\fR routines manipulate the
background of the named window.
The window background is a \fBcchar_t\fR consisting of
any combination of attributes (i.e., rendition) and a complex character.
The attribute part of the background is combined (OR'ed) with all non-blank
characters that are written into the window with \fBwaddch\fR.
Both
the character and attribute parts of the background are combined with
the blank characters.
The background becomes a property of the
character and moves with the character through any scrolling and
insert/delete line/character operations.
.PP
To the extent possible on a
particular terminal, the attribute part of the background is displayed
as the graphic rendition of the character put on the screen.
.SS bkgrnd
.PP
The \fBbkgrnd\fR and \fBwbkgrnd\fR functions
set the background property of the current or specified window
and then apply this setting to every character position in that window:
.bP
The rendition of every character on the screen is changed to
the new background rendition.
.bP
Wherever the former background character
appears, it is changed to the new background character.
.SS getbkgrnd
.PP
The \fBgetbkgrnd\fR function returns the given window's current background
character/attribute pair via the \fBwch\fR pointer.
If the given window pointer is null,
the character is not updated (but no error returned).
.SH NOTES
Note that
\fBbkgrnd\fR,
\fBbkgrndset\fR, and
\fBgetbkgrnd\fR
may be macros.
.PP
X/Open Curses does not provide details on how the rendition is changed.
This implementation follows the approach used in SVr4 curses,
which is explained in the manual page for \fBwbkgd\fP.
.SH RETURN VALUE
.PP
The \fBbkgrndset\fR and \fBwbkgrndset\fR routines do not return a value.
.PP
Upon successful completion, the other functions return \fBOK\fR.
Otherwise, they return \fBERR\fR:
.bP
A null window pointer is treated as an error.
.bP
A null character pointer is treated as an error.
.SH PORTABILITY
.PP
These functions are described in the XSI Curses standard, Issue 4
(X/Open Curses).
.SH SEE ALSO
\fBcurses\fR(3X),
\fBcurs_bkgd\fR(3X)