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41 <H1>curs_color 3x</H1>
44 <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 <H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>,
52 <STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>, <STRONG>COLOR_PAIR</STRONG>
53 - <STRONG>curses</STRONG> color manipulation routines
57 <H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
58 <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG><curses.h></STRONG>
60 <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
61 <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
62 <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>
63 <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
64 <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
65 <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>
67 <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
71 <H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
74 <H3><a name="h3-Overview">Overview</a></H3><PRE>
75 <STRONG>curses</STRONG> support color attributes on terminals with that ca-
76 pability. To use these routines <STRONG>start_color</STRONG> must be
77 called, usually right after <STRONG>initscr</STRONG>. Colors are always
78 used in pairs (referred to as color-pairs). A color-pair
79 consists of a foreground color (for characters) and a
80 background color (for the blank field on which the charac-
81 ters are displayed). A programmer initializes a color-
82 pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
83 tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG><curses.h></STRONG>,
84 can be used as a new video attribute.
86 If a terminal is capable of redefining colors, the pro-
87 grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
88 nition of a color. The routines <STRONG>has_colors</STRONG> and
89 <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
90 whether the terminal has color capabilities and whether
91 the programmer can change the colors. The routine <STRONG>col-</STRONG>
92 <STRONG>or_content</STRONG> allows a programmer to extract the amounts of
93 red, green, and blue components in an initialized color.
94 The routine <STRONG>pair_content</STRONG> allows a programmer to find out
95 how a given color-pair is currently defined.
99 <H3><a name="h3-Routine-Descriptions">Routine Descriptions</a></H3><PRE>
100 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
101 called if the programmer wants to use colors, and before
102 any other color manipulation routine is called. It is
103 good practice to call this routine right after <STRONG>initscr</STRONG>.
104 <STRONG>start_color</STRONG> initializes eight basic colors (black, red,
105 green, yellow, blue, magenta, cyan, and white), and two
106 global variables, <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG> (respectively
107 defining the maximum number of colors and color-pairs the
108 terminal can support). It also restores the colors on the
109 terminal to the values they had when the terminal was just
112 These limits apply to color values and color pairs. Val-
113 ues outside these limits are not legal, and may result in
116 <STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_col-</STRONG>
117 <STRONG>ors</STRONG> capability, which is typically a signed 16-bit in-
118 teger (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
120 <STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
121 <STRONG>ORS-1</STRONG>, inclusive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>).
123 <STRONG>o</STRONG> a special color value <STRONG>-1</STRONG> is used in certain extended
124 functions to denote the <EM>default</EM> <EM>color</EM> (see <STRONG>use_de-</STRONG>
125 <STRONG>fault_colors</STRONG>).
127 <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's
128 <STRONG>max_pairs</STRONG> capability, which is typically a signed
129 16-bit integer (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
131 <STRONG>o</STRONG> legal color pair values are in the range <STRONG>1</STRONG> to <STRONG>COL-</STRONG>
132 <STRONG>OR_PAIRS-1</STRONG>, inclusive.
134 <STRONG>o</STRONG> color pair <STRONG>0</STRONG> is special; it denotes "no color".
136 Color pair <STRONG>0</STRONG> is assumed to be white on black, but is
137 actually whatever the terminal implements before color
138 is initialized. It cannot be modified by the applica-
141 The <STRONG>init_pair</STRONG> routine changes the definition of a color-
142 pair. It takes three arguments: the number of the color-
143 pair to be changed, the foreground color number, and the
144 background color number. For portable applications:
146 <STRONG>o</STRONG> The first argument must be a legal color pair value.
147 If default colors are used (see <STRONG>use_default_colors</STRONG>)
148 the upper limit is adjusted to allow for extra pairs
149 which use a default color in foreground and/or back-
152 <STRONG>o</STRONG> The second and third arguments must be legal color
155 If the color-pair was previously initialized, the screen
156 is refreshed and all occurrences of that color-pair are
157 changed to the new definition.
159 As an extension, ncurses allows you to set color pair <STRONG>0</STRONG>
160 via the <STRONG>assume_default_colors</STRONG> routine, or to specify the
161 use of default colors (color number <STRONG>-1</STRONG>) if you first in-
162 voke the <STRONG>use_default_colors</STRONG> routine.
164 The <STRONG>init_color</STRONG> routine changes the definition of a color.
165 It takes four arguments: the number of the color to be
166 changed followed by three RGB values (for the amounts of
167 red, green, and blue components). The first argument must
168 be a legal color value; default colors are not allowed
169 here. (See the section <STRONG>Colors</STRONG> for the default color in-
170 dex.) Each of the last three arguments must be a value in
171 the range <STRONG>0</STRONG> through <STRONG>1000</STRONG>. When <STRONG>init_color</STRONG> is used, all
172 occurrences of that color on the screen immediately change
173 to the new definition.
175 The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
176 <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
177 returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
178 independent programs. For example, a programmer can use
179 it to decide whether to use color or some other video at-
182 The <STRONG>can_change_color</STRONG> routine requires no arguments. It
183 returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
184 change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
185 routine facilitates writing terminal-independent programs.
187 The <STRONG>color_content</STRONG> routine gives programmers a way to find
188 the intensity of the red, green, and blue (RGB) components
189 in a color. It requires four arguments: the color number,
190 and three addresses of <STRONG>short</STRONG>s for storing the information
191 about the amounts of red, green, and blue components in
192 the given color. The first argument must be a legal color
193 value, i.e., <STRONG>0</STRONG> through <STRONG>COLORS-1</STRONG>, inclusive. The values
194 that are stored at the addresses pointed to by the last
195 three arguments are in the range <STRONG>0</STRONG> (no component) through
196 <STRONG>1000</STRONG> (maximum amount of component), inclusive.
198 The <STRONG>pair_content</STRONG> routine allows programmers to find out
199 what colors a given color-pair consists of. It requires
200 three arguments: the color-pair number, and two addresses
201 of <STRONG>short</STRONG>s for storing the foreground and the background
202 color numbers. The first argument must be a legal color
203 value, i.e., in the range <STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclu-
204 sive. The values that are stored at the addresses pointed
205 to by the second and third arguments are in the range <STRONG>0</STRONG>
206 through <STRONG>COLORS</STRONG>, inclusive.
210 <H3><a name="h3-Colors">Colors</a></H3><PRE>
211 In <STRONG><curses.h></STRONG> the following macros are defined. These are
212 the default colors. <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
213 is the default background color for all terminals.
215 <STRONG>COLOR_BLACK</STRONG>
216 <STRONG>COLOR_RED</STRONG>
217 <STRONG>COLOR_GREEN</STRONG>
218 <STRONG>COLOR_YELLOW</STRONG>
219 <STRONG>COLOR_BLUE</STRONG>
220 <STRONG>COLOR_MAGENTA</STRONG>
221 <STRONG>COLOR_CYAN</STRONG>
222 <STRONG>COLOR_WHITE</STRONG>
226 <H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
227 The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
228 <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
230 All other routines return the integer <STRONG>ERR</STRONG> upon failure and
231 an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
232 <STRONG>ERR</STRONG>") upon successful completion.
234 X/Open defines no error conditions. This implementation
235 will return <STRONG>ERR</STRONG> on attempts to use color values outside
236 the range <STRONG>0</STRONG> to COLORS-1 (except for the default colors ex-
237 tension), or use color pairs outside the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
238 <STRONG>OR_PAIRS-1</STRONG>. Color values used in <STRONG>init_color</STRONG> must be in
239 the range <STRONG>0</STRONG> to <STRONG>1000</STRONG>. An error is returned from all func-
240 tions if the terminal has not been initialized. An error
241 is returned from secondary functions such as <STRONG>init_pair</STRONG> if
242 <STRONG>start_color</STRONG> was not called.
244 <STRONG>init_color</STRONG>
245 returns an error if the terminal does not support
246 this feature, e.g., if the <EM>initialize</EM><STRONG>_</STRONG><EM>color</EM> capa-
247 bility is absent from the terminal description.
249 <STRONG>start_color</STRONG>
250 returns an error if the color table cannot be al-
255 <H2><a name="h2-NOTES">NOTES</a></H2><PRE>
256 In the <EM>ncurses</EM> implementation, there is a separate color
257 activation flag, color palette, color pairs table, and as-
258 sociated COLORS and COLOR_PAIRS counts for each screen;
259 the <STRONG>start_color</STRONG> function only affects the current screen.
260 The SVr4/XSI interface is not really designed with this in
261 mind, and historical implementations may use a single
262 shared color palette.
264 Note that setting an implicit background color via a color
265 pair affects only character cells that a character write
266 operation explicitly touches. To change the background
267 color used when parts of a window are blanked by erasing
268 or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
270 Several caveats apply on 386 and 486 machines with VGA-
273 <STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use
274 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
276 <STRONG>o</STRONG> The A_BLINK attribute should in theory cause the back-
277 ground to go bright. This often fails to work, and
278 even some cards for which it mostly works (such as the
279 Paradise and compatibles) do the wrong thing when you
280 try to set a bright "yellow" background (you get a
281 blinking yellow foreground instead).
283 <STRONG>o</STRONG> Color RGB values are not settable.
287 <H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
288 This implementation satisfies XSI Curses's minimum maxi-
289 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
291 The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
292 ground and background color to support the <STRONG>use_de-</STRONG>
293 <STRONG>fault_colors</STRONG> extension, but only if that routine has been
296 The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
297 color for all terminals can be modified using the <STRONG>as-</STRONG>
298 <STRONG>sume_default_colors</STRONG> extension.
300 This implementation checks the pointers, e.g., for the
301 values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and
302 will treat those as optional parameters when null.
306 <H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
307 <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>
308 <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>, <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
312 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
316 <li><a href="#h2-NAME">NAME</a></li>
317 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
318 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
320 <li><a href="#h3-Overview">Overview</a></li>
321 <li><a href="#h3-Routine-Descriptions">Routine Descriptions</a></li>
322 <li><a href="#h3-Colors">Colors</a></li>
325 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
326 <li><a href="#h2-NOTES">NOTES</a></li>
327 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
328 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>