.\" $OpenBSD: dft_fgbg.3,v 1.5 2000/03/10 01:35:01 millert Exp $
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.\" Author: Thomas E. Dickey <dickey@clark.net> 1997,1999
.\"
.\" $From: dft_fgbg.3x,v 1.9 2000/02/13 02:28:39 tom Exp $
.TH use_default_colors 3 ""
.SH NAME
\fBdft_fgbg\fR \- use terminal's default colors
..
.SH SYNOPSIS
\fB#include <curses.h>\fP

\fBint use_default_colors(void);\fP
.br
\fBint assume_default_colors(int fg, int bg);\fP
..
.SH DESCRIPTION
The
.I use_default_colors()
and
.I assume_default_colors()
functions are extensions to the curses library.
They are used with terminals that support ISO 6429 color, or equivalent.
These terminals allow the application to reset color to an unspecified
default value (e.g., with SGR 39 or SGR 49).
.PP
Applications that paint a colored background over the whole screen
do not take advantage of SGR 39 and SGR 49.
Some applications are designed to work with the default background.
.PP
The first function,
.I use_default_colors()
tells the curses library to assign terminal default
foreground/background colors to color number -1. So init_pair(x,COLOR_RED,-1)
will initialize pair x as red on default background and init_pair(x,-1,COLOR_BLUE) will
initialize pair x as default foreground on blue.
.PP
The other,
.I assume_default_colors()
is a refinement which tells which colors to paint for color pair 0, and -1 means default terminal color.
The following are equivalent:
.RS
.br
.I use_default_colors();
.br
.I assume_default_colors(-1,-1);
.RE
.PP
This is a ncurses extension and for other curses implementations color
number -1 does not mean anything, just as for ncurses before a
successful call of use_default_colors or assume_default_colors.
..
.SH RETURN VALUE
These functions return the integer \fBERR\fP upon failure and \fBOK\fP on success.
They will fail if either the terminal does not support
the \fIorig_pair\fP or \fIorig_colors\fP capability.
If the \fIinitialize_pair\fP capability is found, this causes an
error as well.
..
.SH NOTES
Associated with this extension, the \fBinit_pair\fR(3) function accepts
negative arguments to specify default foreground or background
colors.
..
.SH PORTABILITY
These routines are specific to ncurses.  They were not supported on
Version 7, BSD or System V implementations.  It is recommended that
any code depending on them be conditioned using NCURSES_VERSION.
..
.SH SEE ALSO
\fBcurs_color\fR(3),
\fBded\fP(1).
..
.SH AUTHOR
Thomas Dickey (from an analysis of the requirements for color xterm
for XFree86 3.1.2C, February 1996).
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