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43 <H1 class="no-header">default_colors 3x 2023-08-19 ncurses 6.4 Library calls</H1>
45 <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>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>use_default_colors</STRONG>, <STRONG>assume_default_colors</STRONG> - use terminal's default
55 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
56 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
58 <STRONG>int</STRONG> <STRONG>use_default_colors(void);</STRONG>
59 <STRONG>int</STRONG> <STRONG>assume_default_colors(int</STRONG> <EM>fg</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>bg</EM><STRONG>);</STRONG>
62 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
63 The <STRONG>use_default_colors</STRONG> and <STRONG>assume_default_colors</STRONG> functions are
64 extensions to the curses library. They are used with terminals that
65 support ISO 6429 color, or equivalent. These terminals allow the
66 application to reset color to an unspecified default value (e.g., with
69 Applications that paint a colored background over the whole screen do
70 not take advantage of SGR 39 and SGR 49. Some applications are
71 designed to work with the default background, using colors only for
72 text. For example, there are several implementations of the <STRONG>ls</STRONG> program
73 which use colors to denote different file types or permissions. These
74 "color ls" programs do not necessarily modify the background color,
75 typically using only the <STRONG>setaf</STRONG> terminfo capability to set the
76 foreground color. Full-screen applications that use default colors can
77 achieve similar visual effects.
79 The first function, <STRONG>use_default_colors</STRONG> tells the curses library to
80 assign terminal default foreground/background colors to color number
81 -1. So init_pair(x,COLOR_RED,-1) will initialize pair x as red on
82 default background and init_pair(x,-1,COLOR_BLUE) will initialize pair
83 x as default foreground on blue.
85 The other, <STRONG>assume_default_colors</STRONG> is a refinement which tells which
86 colors to paint for color pair 0. This function recognizes a special
87 color number -1, which denotes the default terminal color.
89 The following are equivalent:
90 <EM>use</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors();</EM>
91 <EM>assume</EM><STRONG>_</STRONG><EM>default</EM><STRONG>_</STRONG><EM>colors(-1,-1);</EM>
93 These are ncurses extensions. For other curses implementations, color
94 number -1 does not mean anything, just as for ncurses before a
95 successful call of <STRONG>use_default_colors</STRONG> or <STRONG>assume_default_colors</STRONG>.
97 Other curses implementations do not allow an application to modify
98 color pair 0. They assume that the background is COLOR_BLACK, but do
99 not ensure that the color pair 0 is painted to match the assumption.
100 If your application does not use either <STRONG>use_default_colors</STRONG> or
101 <STRONG>assume_default_colors</STRONG> ncurses will paint a white foreground (text) with
102 black background for color pair 0.
105 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
106 These functions return the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> on success.
107 They will fail if either the terminal does not support the <STRONG>orig_pair</STRONG> or
108 <STRONG>orig_colors</STRONG> capability. If the <STRONG>initialize_pair</STRONG> capability is not
109 found, this causes an error as well.
112 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
113 Associated with this extension, the <STRONG>init_pair</STRONG> function accepts negative
114 arguments to specify default foreground or background colors.
116 The <STRONG>use_default_colors</STRONG> function was added to support <STRONG>ded</STRONG>. This is a
117 full-screen application which uses curses to manage only part of the
118 screen. The bottom portion of the screen, which is of adjustable size,
119 is left uncolored to display the results from shell commands. The top
120 portion of the screen colors filenames using a scheme like the "color
121 ls" programs. Attempting to manage the background color of the screen
122 for this application would give unsatisfactory results for a variety of
123 reasons. This extension was devised after noting that color xterm (and
124 similar programs) provides a background color which does not
125 necessarily correspond to any of the ANSI colors. While a special
126 terminfo entry could be constructed using nine colors, there was no
127 mechanism provided within curses to account for the related <STRONG>orig_pair</STRONG>
128 and <STRONG>back_color_erase</STRONG> capabilities.
130 The <STRONG>assume_default_colors</STRONG> function was added to solve a different
131 problem: support for applications which would use environment variables
132 and other configuration to bypass curses' notion of the terminal's
133 default colors, setting specific values.
136 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
137 These routines are specific to ncurses. They were not supported on
138 Version 7, BSD or System V implementations. It is recommended that any
139 code depending on them be conditioned using NCURSES_VERSION.
142 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
143 <STRONG>ded(1)</STRONG>, <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>.
146 </PRE><H2><a name="h2-AUTHOR">AUTHOR</a></H2><PRE>
147 Thomas Dickey (from an analysis of the requirements for color xterm for
148 XFree86 3.1.2C, February 1996).
152 ncurses 6.4 2023-08-19 <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
156 <li><a href="#h2-NAME">NAME</a></li>
157 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
158 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
159 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
160 <li><a href="#h2-NOTES">NOTES</a></li>
161 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
162 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
163 <li><a href="#h2-AUTHOR">AUTHOR</a></li>