blob: 8d0f00c6368ac4e1f5e80c8b0314d466bee0ddf1 [file] [log] [blame]
* Copyright (c) 1998-2010,2015 Free Software Foundation, Inc. *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the *
* "Software"), to deal in the Software without restriction, including *
* without limitation the rights to use, copy, modify, merge, publish, *
* distribute, distribute with modifications, sublicense, and/or sell *
* copies of the Software, and to permit persons to whom the Software is *
* furnished to do so, subject to the following conditions: *
* *
* The above copyright notice and this permission notice shall be included *
* in all copies or substantial portions of the Software. *
* *
* *
* Except as contained in this notice, the name(s) of the above copyright *
* holders shall not be used in advertising or otherwise to promote the *
* sale, use or other dealings in this Software without prior written *
* authorization. *
* @Id: curs_color.3x,v 1.39 2015/06/06 23:29:02 tom Exp @
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="generator" content="Manpage converted by man2html - see">
<TITLE>curs_color 3x</TITLE>
<link rev=made href="">
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<H1 class="no-header">curs_color 3x</H1>
<STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
<H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>,
<STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>, <STRONG>COLOR_PAIR</STRONG>
- <STRONG>curses</STRONG> color manipulation routines
<H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
<STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
<STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
<STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
<STRONG>int</STRONG> <STRONG>color_content(short</STRONG> <STRONG>color,</STRONG> <STRONG>short</STRONG> <STRONG>*r,</STRONG> <STRONG>short</STRONG> <STRONG>*g,</STRONG> <STRONG>short</STRONG>
<STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
<H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
<H3><a name="h3-Overview">Overview</a></H3><PRE>
<STRONG>curses</STRONG> supports color attributes on terminals with that
capability. To use these routines <STRONG>start_color</STRONG> must be
called, usually right after <STRONG>initscr</STRONG>. Colors are always
used in pairs (referred to as color-pairs). A color-pair
consists of a foreground color (for characters) and a
background color (for the blank field on which the charac-
ters are displayed). A programmer initializes a color-
pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG>&lt;curses.h&gt;</STRONG>,
can be used as a new video attribute.
If a terminal is capable of redefining colors, the pro-
grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
nition of a color. The routines <STRONG>has_colors</STRONG> and
<STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
whether the terminal has color capabilities and whether
the programmer can change the colors. The routine <STRONG>col-</STRONG>
<STRONG>or_content</STRONG> allows a programmer to extract the amounts of
red, green, and blue components in an initialized color.
The routine <STRONG>pair_content</STRONG> allows a programmer to find out
how a given color-pair is currently defined.
<H3><a name="h3-Color-Rendering">Color Rendering</a></H3><PRE>
The <STRONG>curses</STRONG> library combines these inputs to produce the
actual foreground and background colors shown on the
<STRONG>o</STRONG> per-character video attributes (e.g., via <STRONG>waddch</STRONG>),
<STRONG>o</STRONG> the window attribute (e.g., by <STRONG>wattrset</STRONG>), and
<STRONG>o</STRONG> the background character (e.g., <STRONG>wbkgdset</STRONG>).
Per-character and window attributes are usually set by a
parameter containing video attributes including a <STRONG>COL-</STRONG>
<STRONG>OR_PAIR</STRONG> value. Some functions such as <STRONG>wattr_set</STRONG> use a
separate parameter which is the color pair number.
The background character is a special case: it includes a
character value, just as if it were passed to <STRONG>waddch</STRONG>.
The <STRONG>curses</STRONG> library does the actual work of combining these
color pairs in an internal function called from <STRONG>waddch</STRONG>:
<STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>blank</EM>, and it us-
es the special color pair 0,
<STRONG>o</STRONG> <STRONG>curses</STRONG> next checks the window attribute.
<STRONG>o</STRONG> If the window attribute does not use color pair 0,
<STRONG>curses</STRONG> uses the color pair from the window at-
<STRONG>o</STRONG> Otherwise, <STRONG>curses</STRONG> uses the background character.
<STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>not</EM> <EM>blank</EM>, or it
does not use the special color pair 0, <STRONG>curses</STRONG> prefers
the color pair from the parameter, if it is nonzero.
Otherwise, it tries the window attribute next, and fi-
nally the background character.
Some <STRONG>curses</STRONG> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those
do not combine its parameter with a color pair. Conse-
quently those calls use only the window attribute or the
background character.
<H3><a name="h3-Routine-Descriptions">Routine Descriptions</a></H3><PRE>
The <STRONG>start_color</STRONG> routine requires no arguments. It must be
called if the programmer wants to use colors, and before
any other color manipulation routine is called. It is
good practice to call this routine right after <STRONG>initscr</STRONG>.
<STRONG>start_color</STRONG> does this:
<STRONG>o</STRONG> It initializes two global variables, <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG>
<STRONG>OR_PAIRS</STRONG> (respectively defining the maximum number of
colors and color-pairs the terminal can support).
<STRONG>o</STRONG> It initializes the special color pair <STRONG>0</STRONG> to the default
foreground and background colors. No other color
pairs are initialized.
<STRONG>o</STRONG> It restores the colors on the terminal to the values
they had when the terminal was just turned on.
<STRONG>o</STRONG> If the terminal supports the <STRONG>initc</STRONG> (<STRONG>initialize_color</STRONG>)
capability, <STRONG>start_color</STRONG> initializes its internal table
representing the red, green and blue components of the
color palette.
The components depend on whether the terminal uses CGA
(aka "ANSI") or HLS (i.e., the <STRONG>hls</STRONG> (<STRONG>hue_lightness_sat-</STRONG>
<STRONG>uration</STRONG>) capability is set). The table is initialized
first for eight basic colors (black, red, green, yel-
low, blue, magenta, cyan, and white), and after that
(if the terminal supports more than eight colors) the
components are initialized to <STRONG>1000</STRONG>.
<STRONG>start_color</STRONG> does not attempt to set the terminal's
color palette to match its built-in table. An appli-
cation may use <STRONG>init_color</STRONG> to alter the internal table
along with the terminal's color.
These limits apply to color values and color pairs. Val-
ues outside these limits are not legal, and may result in
a runtime error:
<STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_col-</STRONG>
<STRONG>ors</STRONG> capability, which is typically a signed 16-bit in-
teger (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
<STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
<STRONG>ORS-1</STRONG>, inclusive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>).
<STRONG>o</STRONG> a special color value <STRONG>-1</STRONG> is used in certain extended
functions to denote the <EM>default</EM> <EM>color</EM> (see <STRONG>use_de-</STRONG>
<STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's
<STRONG>max_pairs</STRONG> capability, which is typically a signed
16-bit integer (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
<STRONG>o</STRONG> legal color pair values are in the range <STRONG>1</STRONG> to <STRONG>COL-</STRONG>
<STRONG>OR_PAIRS-1</STRONG>, inclusive.
<STRONG>o</STRONG> color pair <STRONG>0</STRONG> is special; it denotes "no color".
Color pair <STRONG>0</STRONG> is assumed to be white on black, but is
actually whatever the terminal implements before color
is initialized. It cannot be modified by the applica-
The <STRONG>init_pair</STRONG> routine changes the definition of a color-
pair. It takes three arguments: the number of the color-
pair to be changed, the foreground color number, and the
background color number. For portable applications:
<STRONG>o</STRONG> The first argument must be a legal color pair value.
If default colors are used (see <STRONG>use_default_colors</STRONG>)
the upper limit is adjusted to allow for extra pairs
which use a default color in foreground and/or back-
<STRONG>o</STRONG> The second and third arguments must be legal color
If the color-pair was previously initialized, the screen
is refreshed and all occurrences of that color-pair are
changed to the new definition.
As an extension, ncurses allows you to set color pair <STRONG>0</STRONG>
via the <STRONG>assume_default_colors</STRONG> routine, or to specify the
use of default colors (color number <STRONG>-1</STRONG>) if you first in-
voke the <STRONG>use_default_colors</STRONG> routine.
The <STRONG>init_color</STRONG> routine changes the definition of a color.
It takes four arguments: the number of the color to be
changed followed by three RGB values (for the amounts of
red, green, and blue components). The first argument must
be a legal color value; default colors are not allowed
here. (See the section <STRONG>Colors</STRONG> for the default color in-
dex.) Each of the last three arguments must be a value in
the range <STRONG>0</STRONG> through <STRONG>1000</STRONG>. When <STRONG>init_color</STRONG> is used, all
occurrences of that color on the screen immediately change
to the new definition.
The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
<STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
independent programs. For example, a programmer can use
it to decide whether to use color or some other video at-
The <STRONG>can_change_color</STRONG> routine requires no arguments. It
returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
routine facilitates writing terminal-independent programs.
The <STRONG>color_content</STRONG> routine gives programmers a way to find
the intensity of the red, green, and blue (RGB) components
in a color. It requires four arguments: the color number,
and three addresses of <STRONG>short</STRONG>s for storing the information
about the amounts of red, green, and blue components in
the given color. The first argument must be a legal color
value, i.e., <STRONG>0</STRONG> through <STRONG>COLORS-1</STRONG>, inclusive. The values
that are stored at the addresses pointed to by the last
three arguments are in the range <STRONG>0</STRONG> (no component) through
<STRONG>1000</STRONG> (maximum amount of component), inclusive.
The <STRONG>pair_content</STRONG> routine allows programmers to find out
what colors a given color-pair consists of. It requires
three arguments: the color-pair number, and two addresses
of <STRONG>short</STRONG>s for storing the foreground and the background
color numbers. The first argument must be a legal color
value, i.e., in the range <STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclu-
sive. The values that are stored at the addresses pointed
to by the second and third arguments are in the range <STRONG>0</STRONG>
through <STRONG>COLORS</STRONG>, inclusive.
<H3><a name="h3-Colors">Colors</a></H3><PRE>
In <STRONG>&lt;curses.h&gt;</STRONG> the following macros are defined. These are
the standard colors (ISO-6429). <STRONG>curses</STRONG> also assumes that
<STRONG>COLOR_BLACK</STRONG> is the default background color for all termi-
<H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
All other routines return the integer <STRONG>ERR</STRONG> upon failure and
an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
<STRONG>ERR</STRONG>") upon successful completion.
X/Open defines no error conditions. This implementation
will return <STRONG>ERR</STRONG> on attempts to use color values outside
the range <STRONG>0</STRONG> to COLORS-1 (except for the default colors ex-
tension), or use color pairs outside the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
<STRONG>OR_PAIRS-1</STRONG>. Color values used in <STRONG>init_color</STRONG> must be in
the range <STRONG>0</STRONG> to <STRONG>1000</STRONG>. An error is returned from all func-
tions if the terminal has not been initialized. An error
is returned from secondary functions such as <STRONG>init_pair</STRONG> if
<STRONG>start_color</STRONG> was not called.
returns an error if the terminal does not support
this feature, e.g., if the <EM>initialize</EM><STRONG>_</STRONG><EM>color</EM> capa-
bility is absent from the terminal description.
returns an error if the color table cannot be al-
<H2><a name="h2-NOTES">NOTES</a></H2><PRE>
In the <EM>ncurses</EM> implementation, there is a separate color
activation flag, color palette, color pairs table, and as-
sociated COLORS and COLOR_PAIRS counts for each screen;
the <STRONG>start_color</STRONG> function only affects the current screen.
The SVr4/XSI interface is not really designed with this in
mind, and historical implementations may use a single
shared color palette.
Note that setting an implicit background color via a color
pair affects only character cells that a character write
operation explicitly touches. To change the background
color used when parts of a window are blanked by erasing
or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
Several caveats apply on 386 and 486 machines with VGA-
compatible graphics:
<STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use
COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
<STRONG>o</STRONG> The A_BLINK attribute should in theory cause the back-
ground to go bright. This often fails to work, and
even some cards for which it mostly works (such as the
Paradise and compatibles) do the wrong thing when you
try to set a bright "yellow" background (you get a
blinking yellow foreground instead).
<STRONG>o</STRONG> Color RGB values are not settable.
<H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
This implementation satisfies XSI Curses's minimum maxi-
The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
ground and background color to support the <STRONG>use_de-</STRONG>
<STRONG>fault_colors</STRONG> extension, but only if that routine has been
first invoked.
The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
color for all terminals can be modified using the <STRONG>as-</STRONG>
<STRONG>sume_default_colors</STRONG> extension.
This implementation checks the pointers, e.g., for the
values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and
will treat those as optional parameters when null.
<H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG>curs_vari-</STRONG>
<STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>, <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
<STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
<div class="nav">
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<li><a href="#h3-Overview">Overview</a></li>
<li><a href="#h3-Color-Rendering">Color Rendering</a></li>
<li><a href="#h3-Routine-Descriptions">Routine Descriptions</a></li>
<li><a href="#h3-Colors">Colors</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-SEE-ALSO">SEE ALSO</a></li>