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<H1 class="no-header">default_colors 3x 2024-04-13 ncurses 6.6 Library calls</H1>
<PRE>
<STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG> Library calls <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>use_default_colors</STRONG>, <STRONG>assume_default_colors</STRONG> - use terminal's default
colors in <EM>curses</EM>
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>int</STRONG> <STRONG>use_default_colors(void);</STRONG>
<STRONG>int</STRONG> <STRONG>assume_default_colors(int</STRONG> <EM>fg</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>bg</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
The <STRONG>use_default_colors</STRONG> and <STRONG>assume_default_colors</STRONG> 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).
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, using colors only for
text. For example, there are several implementations of the <STRONG>ls</STRONG> program
which use colors to denote different file types or permissions. These
"color ls" programs do not necessarily modify the background color,
typically using only the <STRONG>setaf</STRONG> terminfo capability to set the
foreground color. Full-screen applications that use default colors can
achieve similar visual effects.
The first function, <STRONG>use_default_colors</STRONG> 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.
The other, <STRONG>assume_default_colors</STRONG> is a refinement which tells which
colors to paint for color pair 0. This function recognizes a special
color number -1, which denotes the default terminal color.
The following are equivalent:
<EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors();</EM>
<EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors(-1,-1);</EM>
These are <EM>ncurses</EM> extensions. For other curses implementations, color
number -1 does not mean anything, just as for <EM>ncurses</EM> before a
successful call of <STRONG>use_default_colors</STRONG> or <STRONG>assume_default_colors</STRONG>.
Other curses implementations do not allow an application to modify
color pair 0. They assume that the background is COLOR_BLACK, but do
not ensure that the color pair 0 is painted to match the assumption.
If your application does not use either <STRONG>use_default_colors</STRONG> or
<STRONG>assume_default_colors</STRONG> <EM>ncurses</EM> will paint a white foreground (text) with
black background for color pair 0.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
These functions return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> on success.
They will fail if either the terminal does not support the <STRONG>orig_pair</STRONG> or
<STRONG>orig_colors</STRONG> capability. If the <STRONG>initialize_pair</STRONG> capability is not
found, this causes an error as well.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
Associated with this extension, the <STRONG>init_pair</STRONG> function accepts negative
arguments to specify default foreground or background colors.
The <STRONG>use_default_colors</STRONG> function was added to support <STRONG>ded</STRONG>. This is a
full-screen application which uses curses to manage only part of the
screen. The bottom portion of the screen, which is of adjustable size,
is left uncolored to display the results from shell commands. The top
portion of the screen colors filenames using a scheme like the "color
ls" programs. Attempting to manage the background color of the screen
for this application would give unsatisfactory results for a variety of
reasons. This extension was devised after noting that color xterm (and
similar programs) provides a background color which does not
necessarily correspond to any of the ANSI colors. While a special
terminfo entry could be constructed using nine colors, there was no
mechanism provided within curses to account for the related <STRONG>orig_pair</STRONG>
and <STRONG>back_color_erase</STRONG> capabilities.
The <STRONG>assume_default_colors</STRONG> function was added to solve a different
problem: support for applications which would use environment variables
and other configuration to bypass curses' notion of the terminal's
default colors, setting specific values.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
These routines are specific to <EM>ncurses</EM>. 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.
</PRE><H2><a name="h2-AUTHORS">AUTHORS</a></H2><PRE>
Thomas Dickey (from an analysis of the requirements for color xterm for
XFree86 3.1.2C, February 1996).
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG>ded(1)</STRONG>, <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
ncurses 6.6 2024-04-13 <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
</PRE>
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<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-AUTHORS">AUTHORS</a></li>
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