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30 * @Id: curs_color.3x,v 1.28 2005/12/18 00:00:37 tom Exp @
34 <TITLE>curs_color 3x</TITLE>
35 <link rev=made href="mailto:bug-ncurses@gnu.org">
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39 <H1>curs_color 3x</H1>
42 <!-- Manpage converted by man2html 3.0.1 -->
43 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
50 <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>,
51 <STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>, <STRONG>COLOR_PAIR</STRONG>
52 - <STRONG>curses</STRONG> color manipulation routines
56 <H2>SYNOPSIS</H2><PRE>
57 <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG><curses.h></STRONG>
58 <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
59 <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
60 <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>
61 <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
62 <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
63 <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>
65 <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
69 <H2>DESCRIPTION</H2><PRE>
70 <STRONG>Overview</STRONG>
71 <STRONG>curses</STRONG> support color attributes on terminals with that ca-
72 pability. To use these routines <STRONG>start_color</STRONG> must be
73 called, usually right after <STRONG>initscr</STRONG>. Colors are always
74 used in pairs (referred to as color-pairs). A color-pair
75 consists of a foreground color (for characters) and a
76 background color (for the blank field on which the charac-
77 ters are displayed). A programmer initializes a color-
78 pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
79 tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG><curses.h></STRONG>,
80 can be used as a new video attribute.
82 If a terminal is capable of redefining colors, the pro-
83 grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
84 nition of a color. The routines <STRONG>has_colors</STRONG> and
85 <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
86 whether the terminal has color capabilities and whether
87 the programmer can change the colors. The routine <STRONG>col-</STRONG>
88 <STRONG>or_content</STRONG> allows a programmer to extract the amounts of
89 red, green, and blue components in an initialized color.
90 The routine <STRONG>pair_content</STRONG> allows a programmer to find out
91 how a given color-pair is currently defined.
93 <STRONG>Routine</STRONG> <STRONG>Descriptions</STRONG>
94 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
95 called if the programmer wants to use colors, and before
96 any other color manipulation routine is called. It is
97 good practice to call this routine right after <STRONG>initscr</STRONG>.
98 <STRONG>start_color</STRONG> initializes eight basic colors (black, red,
99 green, yellow, blue, magenta, cyan, and white), and two
100 global variables, <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG> (respectively
101 defining the maximum number of colors and color-pairs the
102 terminal can support). It also restores the colors on the
103 terminal to the values they had when the terminal was just
106 The <STRONG>init_pair</STRONG> routine changes the definition of a color-
107 pair. It takes three arguments: the number of the color-
108 pair to be changed, the foreground color number, and the
109 background color number. For portable applications:
111 - The value of the first argument must be between <STRONG>1</STRONG> and
112 <STRONG>COLOR_PAIRS-1</STRONG>.
114 - The value of the second and third arguments must be
115 between 0 and <STRONG>COLORS</STRONG>. Color pair 0 is assumed to be
116 white on black, but is actually whatever the terminal
117 implements before color is initialized. It cannot be
118 modified by the application.
120 If the color-pair was previously initialized, the screen
121 is refreshed and all occurrences of that color-pair are
122 changed to the new definition.
124 As an extension, ncurses allows you to set color pair 0
125 via the <STRONG>assume_default_colors</STRONG> routine, or to specify the
126 use of default colors (color number <STRONG>-1</STRONG>) if you first in-
127 voke the <STRONG>use_default_colors</STRONG> routine.
129 The <STRONG>init_color</STRONG> routine changes the definition of a color.
130 It takes four arguments: the number of the color to be
131 changed followed by three RGB values (for the amounts of
132 red, green, and blue components). The value of the first
133 argument must be between <STRONG>0</STRONG> and <STRONG>COLORS</STRONG>. (See the section
134 <STRONG>Colors</STRONG> for the default color index.) Each of the last
135 three arguments must be a value between 0 and 1000. When
136 <STRONG>init_color</STRONG> is used, all occurrences of that color on the
137 screen immediately change to the new definition.
139 The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
140 <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
141 returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
142 independent programs. For example, a programmer can use
143 it to decide whether to use color or some other video at-
146 The <STRONG>can_change_color</STRONG> routine requires no arguments. It
147 returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
148 change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
149 routine facilitates writing terminal-independent programs.
151 The <STRONG>color_content</STRONG> routine gives programmers a way to find
152 the intensity of the red, green, and blue (RGB) components
153 in a color. It requires four arguments: the color number,
154 and three addresses of <STRONG>short</STRONG>s for storing the information
155 about the amounts of red, green, and blue components in
156 the given color. The value of the first argument must be
157 between 0 and <STRONG>COLORS</STRONG>. The values that are stored at the
158 addresses pointed to by the last three arguments are be-
159 tween 0 (no component) and 1000 (maximum amount of compo-
162 The <STRONG>pair_content</STRONG> routine allows programmers to find out
163 what colors a given color-pair consists of. It requires
164 three arguments: the color-pair number, and two addresses
165 of <STRONG>short</STRONG>s for storing the foreground and the background
166 color numbers. The value of the first argument must be
167 between 1 and <STRONG>COLOR_PAIRS-1</STRONG>. The values that are stored
168 at the addresses pointed to by the second and third argu-
169 ments are between 0 and <STRONG>COLORS</STRONG>.
171 <STRONG>Colors</STRONG>
172 In <STRONG><curses.h></STRONG> the following macros are defined. These are
173 the default colors. <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
174 is the default background color for all terminals.
176 <STRONG>COLOR_BLACK</STRONG>
177 <STRONG>COLOR_RED</STRONG>
178 <STRONG>COLOR_GREEN</STRONG>
179 <STRONG>COLOR_YELLOW</STRONG>
180 <STRONG>COLOR_BLUE</STRONG>
181 <STRONG>COLOR_MAGENTA</STRONG>
182 <STRONG>COLOR_CYAN</STRONG>
183 <STRONG>COLOR_WHITE</STRONG>
187 <H2>RETURN VALUE</H2><PRE>
188 The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
189 <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
191 All other routines return the integer <STRONG>ERR</STRONG> upon failure and
192 an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
193 <STRONG>ERR</STRONG>") upon successful completion.
195 X/Open defines no error conditions. This implementation
196 will return <STRONG>ERR</STRONG> on attempts to use color values outside
197 the range 0 to COLORS-1 (except for the default colors ex-
198 tension), or use color pairs outside the range 0 to COL-
199 OR_PAIR-1. Color values used in <STRONG>init_color</STRONG> must be in the
200 range 0 to 1000. An error is returned from all functions
201 if the terminal has not been initialized. An error is re-
202 turned from secondary functions such as <STRONG>init_pair</STRONG> if
203 <STRONG>start_color</STRONG> was not called.
205 <STRONG>init_color</STRONG>
206 returns an error if the terminal does not sup-
207 port this feature, e.g., if the <EM>initial-</EM>
208 <EM>ize</EM><STRONG>_</STRONG><EM>color</EM> capability is absent from the termi-
211 <STRONG>start_color</STRONG>
212 returns an error If the color table cannot be
218 In the <EM>ncurses</EM> implementation, there is a separate color
219 activation flag, color palette, color pairs table, and as-
220 sociated COLORS and COLOR_PAIRS counts for each screen;
221 the <STRONG>start_color</STRONG> function only affects the current screen.
222 The SVr4/XSI interface is not really designed with this in
223 mind, and historical implementations may use a single
224 shared color palette.
226 Note that setting an implicit background color via a color
227 pair affects only character cells that a character write
228 operation explicitly touches. To change the background
229 color used when parts of a window are blanked by erasing
230 or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
232 Several caveats apply on 386 and 486 machines with VGA-
235 - COLOR_YELLOW is actually brown. To get yellow, use
236 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
238 - The A_BLINK attribute should in theory cause the
239 background to go bright. This often fails to work,
240 and even some cards for which it mostly works (such
241 as the Paradise and compatibles) do the wrong thing
242 when you try to set a bright "yellow" background (you
243 get a blinking yellow foreground instead).
245 - Color RGB values are not settable.
249 <H2>PORTABILITY</H2><PRE>
250 This implementation satisfies XSI Curses's minimum maxi-
251 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
253 The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
254 ground and background color to support the <STRONG>use_de-</STRONG>
255 <STRONG>fault_colors</STRONG> extension, but only if that routine has been
258 The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
259 color for all terminals can be modified using the <STRONG>as-</STRONG>
260 <STRONG>sume_default_colors</STRONG> extension.
262 This implementation checks the pointers, e.g., for the
263 values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and
264 will treat those as optional parameters when null.
268 <H2>SEE ALSO</H2><PRE>
269 <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>default_col-</STRONG>
270 <STRONG><A HREF="default_colors.3x.html">ors(3x)</A></STRONG>
274 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
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