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29 * @Id: curs_color.3x,v 1.38 2015/05/23 21:36:35 tom Exp @
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41 <H1 class="no-header">curs_color 3x</H1>
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>
49 <H2><a name="h2-NAME">NAME</a></H2><PRE>
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><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
57 <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG><curses.h></STRONG>
59 <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
60 <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
61 <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>
62 <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
63 <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
64 <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>
66 <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
70 <H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
73 <H3><a name="h3-Overview">Overview</a></H3><PRE>
74 <STRONG>curses</STRONG> supports color attributes on terminals with that
75 capability. To use these routines <STRONG>start_color</STRONG> must be
76 called, usually right after <STRONG>initscr</STRONG>. Colors are always
77 used in pairs (referred to as color-pairs). A color-pair
78 consists of a foreground color (for characters) and a
79 background color (for the blank field on which the charac-
80 ters are displayed). A programmer initializes a color-
81 pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
82 tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG><curses.h></STRONG>,
83 can be used as a new video attribute.
85 If a terminal is capable of redefining colors, the pro-
86 grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
87 nition of a color. The routines <STRONG>has_colors</STRONG> and
88 <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
89 whether the terminal has color capabilities and whether
90 the programmer can change the colors. The routine <STRONG>col-</STRONG>
91 <STRONG>or_content</STRONG> allows a programmer to extract the amounts of
92 red, green, and blue components in an initialized color.
93 The routine <STRONG>pair_content</STRONG> allows a programmer to find out
94 how a given color-pair is currently defined.
98 <H3><a name="h3-Color-Rendering">Color Rendering</a></H3><PRE>
99 The <STRONG>curses</STRONG> library combines these inputs to produce the
100 actual foreground and background colors shown on the
103 <STRONG>o</STRONG> per-character video attributes (e.g., via <STRONG>waddch</STRONG>),
105 <STRONG>o</STRONG> the window attribute (e.g., by <STRONG>wattrset</STRONG>), and
107 <STRONG>o</STRONG> the background character (e.g., <STRONG>wbkgdset</STRONG>).
109 Per-character and window attributes are usually set by a
110 parameter containing video attributes including a <STRONG>COL-</STRONG>
111 <STRONG>OR_PAIR</STRONG> value. Some functions such as <STRONG>wattr_set</STRONG> use a
112 separate parameter which is the color pair number.
114 The background character is a special case: it includes a
115 character value, just as if it were passed to <STRONG>waddch</STRONG>.
117 The <STRONG>curses</STRONG> library does the actual work of combining these
118 color pairs in an internal function called from <STRONG>waddch</STRONG>:
120 <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>blank</EM>, and it us-
121 es the special color pair 0,
123 <STRONG>o</STRONG> <STRONG>curses</STRONG> next checks the window attribute.
125 <STRONG>o</STRONG> If the window attribute does not use color pair 0,
126 <STRONG>curses</STRONG> uses the color pair from the window at-
129 <STRONG>o</STRONG> Otherwise, <STRONG>curses</STRONG> uses the background character.
131 <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>not</EM> <EM>blank</EM>, or it
132 does not use the special color pair 0, <STRONG>curses</STRONG> prefers
133 the color pair from the parameter, if it is nonzero.
134 Otherwise, it tries the window attribute next, and fi-
135 nally the background character.
137 Some <STRONG>curses</STRONG> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those
138 do not combine its parameter with a color pair. Conse-
139 quently those calls use only the window attribute or the
140 background character.
144 <H3><a name="h3-Routine-Descriptions">Routine Descriptions</a></H3><PRE>
145 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
146 called if the programmer wants to use colors, and before
147 any other color manipulation routine is called. It is
148 good practice to call this routine right after <STRONG>initscr</STRONG>.
149 <STRONG>start_color</STRONG> does this:
151 <STRONG>o</STRONG> It initializes two global variables, <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG>
152 <STRONG>OR_PAIRS</STRONG> (respectively defining the maximum number of
153 colors and color-pairs the terminal can support).
155 <STRONG>o</STRONG> It initializes the special color pair <STRONG>0</STRONG> to the default
156 foreground and background colors. No other color
157 pairs are initialized.
159 <STRONG>o</STRONG> It restores the colors on the terminal to the values
160 they had when the terminal was just turned on.
162 <STRONG>o</STRONG> If the terminal supports the <STRONG>initc</STRONG> (<STRONG>initialize_color</STRONG>)
163 capability, <STRONG>start_color</STRONG> initializes its internal table
164 representing the red, green and blue components of the
167 The components depend on whether the terminal uses CGA
168 (aka "ANSI") or HLS (i.e., the <STRONG>hls</STRONG> (<STRONG>hue_lightness_sat-</STRONG>
169 <STRONG>uration</STRONG>) capability is set). The table is initialized
170 first for eight basic colors (black, red, green, yel-
171 low, blue, magenta, cyan, and white), and after that
172 (if the terminal supports more than eight colors) the
173 components are initialized to <STRONG>1000</STRONG>.
175 <STRONG>start_color</STRONG> does not attempt to set the terminal's
176 color palette to match its built-in table. An appli-
177 cation may use <STRONG>init_color</STRONG> to alter the internal table
178 along with the terminal's color.
180 These limits apply to color values and color pairs. Val-
181 ues outside these limits are not legal, and may result in
184 <STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_col-</STRONG>
185 <STRONG>ors</STRONG> capability, which is typically a signed 16-bit in-
186 teger (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
188 <STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
189 <STRONG>ORS-1</STRONG>, inclusive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>).
191 <STRONG>o</STRONG> a special color value <STRONG>-1</STRONG> is used in certain extended
192 functions to denote the <EM>default</EM> <EM>color</EM> (see <STRONG>use_de-</STRONG>
193 <STRONG>fault_colors</STRONG>).
195 <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's
196 <STRONG>max_pairs</STRONG> capability, which is typically a signed
197 16-bit integer (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
199 <STRONG>o</STRONG> legal color pair values are in the range <STRONG>1</STRONG> to <STRONG>COL-</STRONG>
200 <STRONG>OR_PAIRS-1</STRONG>, inclusive.
202 <STRONG>o</STRONG> color pair <STRONG>0</STRONG> is special; it denotes "no color".
204 Color pair <STRONG>0</STRONG> is assumed to be white on black, but is
205 actually whatever the terminal implements before color
206 is initialized. It cannot be modified by the applica-
209 The <STRONG>init_pair</STRONG> routine changes the definition of a color-
210 pair. It takes three arguments: the number of the color-
211 pair to be changed, the foreground color number, and the
212 background color number. For portable applications:
214 <STRONG>o</STRONG> The first argument must be a legal color pair value.
215 If default colors are used (see <STRONG>use_default_colors</STRONG>)
216 the upper limit is adjusted to allow for extra pairs
217 which use a default color in foreground and/or back-
220 <STRONG>o</STRONG> The second and third arguments must be legal color
223 If the color-pair was previously initialized, the screen
224 is refreshed and all occurrences of that color-pair are
225 changed to the new definition.
227 As an extension, ncurses allows you to set color pair <STRONG>0</STRONG>
228 via the <STRONG>assume_default_colors</STRONG> routine, or to specify the
229 use of default colors (color number <STRONG>-1</STRONG>) if you first in-
230 voke the <STRONG>use_default_colors</STRONG> routine.
232 The <STRONG>init_color</STRONG> routine changes the definition of a color.
233 It takes four arguments: the number of the color to be
234 changed followed by three RGB values (for the amounts of
235 red, green, and blue components). The first argument must
236 be a legal color value; default colors are not allowed
237 here. (See the section <STRONG>Colors</STRONG> for the default color in-
238 dex.) Each of the last three arguments must be a value in
239 the range <STRONG>0</STRONG> through <STRONG>1000</STRONG>. When <STRONG>init_color</STRONG> is used, all
240 occurrences of that color on the screen immediately change
241 to the new definition.
243 The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
244 <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
245 returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
246 independent programs. For example, a programmer can use
247 it to decide whether to use color or some other video at-
250 The <STRONG>can_change_color</STRONG> routine requires no arguments. It
251 returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
252 change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
253 routine facilitates writing terminal-independent programs.
255 The <STRONG>color_content</STRONG> routine gives programmers a way to find
256 the intensity of the red, green, and blue (RGB) components
257 in a color. It requires four arguments: the color number,
258 and three addresses of <STRONG>short</STRONG>s for storing the information
259 about the amounts of red, green, and blue components in
260 the given color. The first argument must be a legal color
261 value, i.e., <STRONG>0</STRONG> through <STRONG>COLORS-1</STRONG>, inclusive. The values
262 that are stored at the addresses pointed to by the last
263 three arguments are in the range <STRONG>0</STRONG> (no component) through
264 <STRONG>1000</STRONG> (maximum amount of component), inclusive.
266 The <STRONG>pair_content</STRONG> routine allows programmers to find out
267 what colors a given color-pair consists of. It requires
268 three arguments: the color-pair number, and two addresses
269 of <STRONG>short</STRONG>s for storing the foreground and the background
270 color numbers. The first argument must be a legal color
271 value, i.e., in the range <STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclu-
272 sive. The values that are stored at the addresses pointed
273 to by the second and third arguments are in the range <STRONG>0</STRONG>
274 through <STRONG>COLORS</STRONG>, inclusive.
278 <H3><a name="h3-Colors">Colors</a></H3><PRE>
279 In <STRONG><curses.h></STRONG> the following macros are defined. These are
280 the default colors. <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
281 is the default background color for all terminals.
283 <STRONG>COLOR_BLACK</STRONG>
284 <STRONG>COLOR_RED</STRONG>
285 <STRONG>COLOR_GREEN</STRONG>
286 <STRONG>COLOR_YELLOW</STRONG>
287 <STRONG>COLOR_BLUE</STRONG>
288 <STRONG>COLOR_MAGENTA</STRONG>
289 <STRONG>COLOR_CYAN</STRONG>
290 <STRONG>COLOR_WHITE</STRONG>
294 <H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
295 The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
296 <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
298 All other routines return the integer <STRONG>ERR</STRONG> upon failure and
299 an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
300 <STRONG>ERR</STRONG>") upon successful completion.
302 X/Open defines no error conditions. This implementation
303 will return <STRONG>ERR</STRONG> on attempts to use color values outside
304 the range <STRONG>0</STRONG> to COLORS-1 (except for the default colors ex-
305 tension), or use color pairs outside the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
306 <STRONG>OR_PAIRS-1</STRONG>. Color values used in <STRONG>init_color</STRONG> must be in
307 the range <STRONG>0</STRONG> to <STRONG>1000</STRONG>. An error is returned from all func-
308 tions if the terminal has not been initialized. An error
309 is returned from secondary functions such as <STRONG>init_pair</STRONG> if
310 <STRONG>start_color</STRONG> was not called.
312 <STRONG>init_color</STRONG>
313 returns an error if the terminal does not support
314 this feature, e.g., if the <EM>initialize</EM><STRONG>_</STRONG><EM>color</EM> capa-
315 bility is absent from the terminal description.
317 <STRONG>start_color</STRONG>
318 returns an error if the color table cannot be al-
323 <H2><a name="h2-NOTES">NOTES</a></H2><PRE>
324 In the <EM>ncurses</EM> implementation, there is a separate color
325 activation flag, color palette, color pairs table, and as-
326 sociated COLORS and COLOR_PAIRS counts for each screen;
327 the <STRONG>start_color</STRONG> function only affects the current screen.
328 The SVr4/XSI interface is not really designed with this in
329 mind, and historical implementations may use a single
330 shared color palette.
332 Note that setting an implicit background color via a color
333 pair affects only character cells that a character write
334 operation explicitly touches. To change the background
335 color used when parts of a window are blanked by erasing
336 or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
338 Several caveats apply on 386 and 486 machines with VGA-
341 <STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use
342 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
344 <STRONG>o</STRONG> The A_BLINK attribute should in theory cause the back-
345 ground to go bright. This often fails to work, and
346 even some cards for which it mostly works (such as the
347 Paradise and compatibles) do the wrong thing when you
348 try to set a bright "yellow" background (you get a
349 blinking yellow foreground instead).
351 <STRONG>o</STRONG> Color RGB values are not settable.
355 <H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
356 This implementation satisfies XSI Curses's minimum maxi-
357 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
359 The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
360 ground and background color to support the <STRONG>use_de-</STRONG>
361 <STRONG>fault_colors</STRONG> extension, but only if that routine has been
364 The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
365 color for all terminals can be modified using the <STRONG>as-</STRONG>
366 <STRONG>sume_default_colors</STRONG> extension.
368 This implementation checks the pointers, e.g., for the
369 values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and
370 will treat those as optional parameters when null.
374 <H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
375 <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>
376 <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>, <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
380 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
384 <li><a href="#h2-NAME">NAME</a></li>
385 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
386 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
388 <li><a href="#h3-Overview">Overview</a></li>
389 <li><a href="#h3-Color-Rendering">Color Rendering</a></li>
390 <li><a href="#h3-Routine-Descriptions">Routine Descriptions</a></li>
391 <li><a href="#h3-Colors">Colors</a></li>
394 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
395 <li><a href="#h2-NOTES">NOTES</a></li>
396 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
397 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>