4 <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>,
5 <STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG> - <STRONG>curses</STRONG>
6 color manipulation routines
10 <H2>SYNOPSIS</H2><PRE>
11 <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG><curses.h></STRONG>
12 <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
13 <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
14 <STRONG>int</STRONG> <STRONG>init_color(short</STRONG> <STRONG>color,</STRONG> <STRONG>short</STRONG> <STRONG>r,</STRONG> <STRONG>short</STRONG> <STRONG>g,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
15 <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
16 <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
17 <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>
19 <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
23 <H2>DESCRIPTION</H2><PRE>
24 <STRONG>Overview</STRONG>
25 <STRONG>curses</STRONG> support color attributes on terminals with that
26 capability. To use these routines <STRONG>start_color</STRONG> must be
27 called, usually right after <STRONG>initscr</STRONG>. Colors are always
28 used in pairs (referred to as color-pairs). A color-pair
29 consists of a foreground color (for characters) and a
30 background color (for the blank field on which the charac-
31 ters are displayed). A programmer initializes a color-
32 pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
33 tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG><curses.h></STRONG>,
34 can be used as a new video attribute.
36 If a terminal is capable of redefining colors, the pro-
37 grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
38 nition of a color. The routines <STRONG>has_colors</STRONG> and
39 <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
40 whether the terminal has color capabilities and whether
41 the programmer can change the colors. The routine
42 <STRONG>color_content</STRONG> allows a programmer to extract the amounts
43 of red, green, and blue components in an initialized
44 color. The routine <STRONG>pair_content</STRONG> allows a programmer to
45 find out how a given color-pair is currently defined.
47 <STRONG>Routine</STRONG> <STRONG>Descriptions</STRONG>
48 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
49 called if the programmer wants to use colors, and before
50 any other color manipulation routine is called. It is
51 good practice to call this routine right after <STRONG>initscr</STRONG>.
52 <STRONG>start_color</STRONG> initializes eight basic colors (black, red,
53 green, yellow, blue, magenta, cyan, and white), and two
54 global variables, <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG> (respectively
55 defining the maximum number of colors and color-pairs the
56 terminal can support). It also restores the colors on the
57 terminal to the values they had when the terminal was just
60 pair to be changed, the foreground color number, and the
61 background color number. The value of the first argument
62 must be between <STRONG>1</STRONG> and <STRONG>COLOR_PAIRS-1</STRONG>. The value of the
63 second and third arguments must be between 0 and <STRONG>COLORS</STRONG>
64 (the 0 color pair is wired to white on black and cannot be
65 changed). If the color-pair was previously initialized,
66 the screen is refreshed and all occurrences of that color-
67 pair is changed to the new definition.
69 The <STRONG>init_color</STRONG> routine changes the definition of a color.
70 It takes four arguments: the number of the color to be
71 changed followed by three RGB values (for the amounts of
72 red, green, and blue components). The value of the first
73 argument must be between <STRONG>0</STRONG> and <STRONG>COLORS</STRONG>. (See the section
74 <STRONG>Colors</STRONG> for the default color index.) Each of the last
75 three arguments must be a value between 0 and 1000. When
76 <STRONG>init_color</STRONG> is used, all occurrences of that color on the
77 screen immediately change to the new definition.
79 The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
80 <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
81 returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
82 independent programs. For example, a programmer can use
83 it to decide whether to use color or some other video
86 The <STRONG>can_change_color</STRONG> routine requires no arguments. It
87 returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
88 change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
89 routine facilitates writing terminal-independent programs.
91 The <STRONG>color_content</STRONG> routine gives programmers a way to find
92 the intensity of the red, green, and blue (RGB) components
93 in a color. It requires four arguments: the color number,
94 and three addresses of <STRONG>short</STRONG>s for storing the information
95 about the amounts of red, green, and blue components in
96 the given color. The value of the first argument must be
97 between 0 and <STRONG>COLORS</STRONG>. The values that are stored at the
98 addresses pointed to by the last three arguments are
99 between 0 (no component) and 1000 (maximum amount of com-
102 The <STRONG>pair_content</STRONG> routine allows programmers to find out
103 what colors a given color-pair consists of. It requires
104 three arguments: the color-pair number, and two addresses
105 of <STRONG>short</STRONG>s for storing the foreground and the background
106 color numbers. The value of the first argument must be
107 between 1 and <STRONG>COLOR_PAIRS-1</STRONG>. The values that are stored
108 at the addresses pointed to by the second and third argu-
109 ments are between 0 and <STRONG>COLORS</STRONG>.
111 <STRONG>Colors</STRONG>
112 is the default background color for all terminals.
114 <STRONG>COLOR_BLACK</STRONG>
115 <STRONG>COLOR_RED</STRONG>
116 <STRONG>COLOR_GREEN</STRONG>
117 <STRONG>COLOR_YELLOW</STRONG>
118 <STRONG>COLOR_BLUE</STRONG>
119 <STRONG>COLOR_MAGENTA</STRONG>
120 <STRONG>COLOR_CYAN</STRONG>
121 <STRONG>COLOR_WHITE</STRONG>
125 <H2>RETURN VALUE</H2><PRE>
126 The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
127 <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
129 All other routines return the integer <STRONG>ERR</STRONG> upon failure and
130 an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
131 <STRONG>ERR</STRONG>") upon successful completion.
136 In the <EM>ncurses</EM> implementation, there is a separate color
137 activation flag, color palette, color pairs table, and
138 associated COLORS and COLOR_PAIRS counts for each screen;
139 the <STRONG>start_color</STRONG> function only affects the current screen.
140 The SVr4/XSI interface is not really designed with this in
141 mind, and historical implementations may use a single
142 shared color palette.
144 Note that setting an implicit background color via a color
145 pair affects only character cells that a character write
146 operation explicitly touches. To change the background
147 color used when parts of a window are blanked by erasing
148 or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3X)</A></STRONG>.
150 Several caveats apply on 386 and 486 machines with VGA-
153 COLOR_YELLOW is actually brown. To get yellow, use
154 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
156 The A_BLINK attribute should in theory cause the back-
157 ground to go bright. This often fails to work, and even
158 some cards for which it mostly works (such as the Paradise
159 and compatibles) do the wrong thing when you try to set a
160 bright "yellow" background (you get a blinking yellow
163 Color RGB values are not settable.
167 <H2>PORTABILITY</H2><PRE>
168 This implementation satisfies XSI Curses's minimum maxi-
169 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
170 ground and background color to support the
171 <STRONG>use_default_colors</STRONG> extension, but only if that routine has
176 <H2>SEE ALSO</H2><PRE>
177 <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><A HREF="dft_fgbg.3x.html">dft_fgbg(3X)</A></STRONG>