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29 * @Id: curs_color.3x,v 1.47 2017/03/13 21:49:37 tom Exp @
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44 <H1 class="no-header">curs_color 3x</H1>
46 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
51 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
52 <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>color_content</STRONG>,
53 <STRONG>pair_content</STRONG>, <STRONG>has_colors</STRONG>, <STRONG>can_change_color</STRONG>, <STRONG>COLOR_PAIR</STRONG>,
54 <STRONG>PAIR_NUMBER</STRONG> - <STRONG>curses</STRONG> color manipulation routines
57 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
58 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
60 <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
62 <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
63 <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>
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>
69 <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
70 <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
72 <STRONG>int</STRONG> <STRONG>COLOR_PAIR(int</STRONG> <STRONG>n);</STRONG>
73 <STRONG>PAIR_NUMBER(</STRONG><EM>attrs</EM><STRONG>);</STRONG>
76 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
78 </PRE><H3><a name="h3-Overview">Overview</a></H3><PRE>
79 <STRONG>curses</STRONG> supports color attributes on terminals with that
80 capability. To use these routines <STRONG>start_color</STRONG> must be
81 called, usually right after <STRONG>initscr</STRONG>. Colors are always
82 used in pairs (referred to as color-pairs). A color-pair
83 consists of a foreground color (for characters) and a
84 background color (for the blank field on which the charac-
85 ters are displayed). A programmer initializes a color-
86 pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
87 tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>) can be used to convert the pair to
90 If a terminal is capable of redefining colors, the pro-
91 grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
92 nition of a color. The routines <STRONG>has_colors</STRONG> and
93 <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
94 whether the terminal has color capabilities and whether
95 the programmer can change the colors. The routine <STRONG>col-</STRONG>
96 <STRONG>or_content</STRONG> allows a programmer to extract the amounts of
97 red, green, and blue components in an initialized color.
98 The routine <STRONG>pair_content</STRONG> allows a programmer to find out
99 how a given color-pair is currently defined.
102 </PRE><H3><a name="h3-Color-Rendering">Color Rendering</a></H3><PRE>
103 The <STRONG>curses</STRONG> library combines these inputs to produce the
104 actual foreground and background colors shown on the
107 <STRONG>o</STRONG> per-character video attributes (e.g., via <STRONG>waddch</STRONG>),
109 <STRONG>o</STRONG> the window attribute (e.g., by <STRONG>wattrset</STRONG>), and
111 <STRONG>o</STRONG> the background character (e.g., <STRONG>wbkgdset</STRONG>).
113 Per-character and window attributes are usually set by a
114 parameter containing video attributes including a color
115 pair value. Some functions such as <STRONG>wattr_set</STRONG> use a sepa-
116 rate parameter which is the color pair number.
118 The background character is a special case: it includes a
119 character value, just as if it were passed to <STRONG>waddch</STRONG>.
121 The <STRONG>curses</STRONG> library does the actual work of combining these
122 color pairs in an internal function called from <STRONG>waddch</STRONG>:
124 <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>blank</EM>, and it us-
125 es the special color pair 0,
127 <STRONG>o</STRONG> <STRONG>curses</STRONG> next checks the window attribute.
129 <STRONG>o</STRONG> If the window attribute does not use color pair 0,
130 <STRONG>curses</STRONG> uses the color pair from the window at-
133 <STRONG>o</STRONG> Otherwise, <STRONG>curses</STRONG> uses the background character.
135 <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>not</EM> <EM>blank</EM>, or it
136 does not use the special color pair 0, <STRONG>curses</STRONG> prefers
137 the color pair from the parameter, if it is nonzero.
138 Otherwise, it tries the window attribute next, and fi-
139 nally the background character.
141 Some <STRONG>curses</STRONG> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those
142 do not combine its parameter with a color pair. Conse-
143 quently those calls use only the window attribute or the
144 background character.
147 </PRE><H3><a name="h3-Routine-Descriptions">Routine Descriptions</a></H3><PRE>
148 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
149 called if the programmer wants to use colors, and before
150 any other color manipulation routine is called. It is
151 good practice to call this routine right after <STRONG>initscr</STRONG>.
152 <STRONG>start_color</STRONG> does this:
154 <STRONG>o</STRONG> It initializes two global variables, <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG>
155 <STRONG>OR_PAIRS</STRONG> (respectively defining the maximum number of
156 colors and color-pairs the terminal can support).
158 <STRONG>o</STRONG> It initializes the special color pair <STRONG>0</STRONG> to the default
159 foreground and background colors. No other color
160 pairs are initialized.
162 <STRONG>o</STRONG> It restores the colors on the terminal to the values
163 they had when the terminal was just turned on.
165 <STRONG>o</STRONG> If the terminal supports the <STRONG>initc</STRONG> (<STRONG>initialize_color</STRONG>)
166 capability, <STRONG>start_color</STRONG> initializes its internal table
167 representing the red, green and blue components of the
170 The components depend on whether the terminal uses CGA
171 (aka "ANSI") or HLS (i.e., the <STRONG>hls</STRONG> (<STRONG>hue_lightness_sat-</STRONG>
172 <STRONG>uration</STRONG>) capability is set). The table is initialized
173 first for eight basic colors (black, red, green, yel-
174 low, blue, magenta, cyan, and white), and after that
175 (if the terminal supports more than eight colors) the
176 components are initialized to <STRONG>1000</STRONG>.
178 <STRONG>start_color</STRONG> does not attempt to set the terminal's
179 color palette to match its built-in table. An appli-
180 cation may use <STRONG>init_color</STRONG> to alter the internal table
181 along with the terminal's color.
183 These limits apply to color values and color pairs. Val-
184 ues outside these limits are not legal, and may result in
187 <STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_col-</STRONG>
188 <STRONG>ors</STRONG> capability, which is typically a signed 16-bit in-
189 teger (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
191 <STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
192 <STRONG>ORS-1</STRONG>, inclusive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>).
194 <STRONG>o</STRONG> a special color value <STRONG>-1</STRONG> is used in certain extended
195 functions to denote the <EM>default</EM> <EM>color</EM> (see <STRONG>use_de-</STRONG>
196 <STRONG>fault_colors</STRONG>).
198 <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's
199 <STRONG>max_pairs</STRONG> capability, which is typically a signed
200 16-bit integer (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
202 <STRONG>o</STRONG> legal color pair values are in the range <STRONG>1</STRONG> to <STRONG>COL-</STRONG>
203 <STRONG>OR_PAIRS-1</STRONG>, inclusive.
205 <STRONG>o</STRONG> color pair <STRONG>0</STRONG> is special; it denotes "no color".
207 Color pair <STRONG>0</STRONG> is assumed to be white on black, but is
208 actually whatever the terminal implements before color
209 is initialized. It cannot be modified by the applica-
212 The <STRONG>init_pair</STRONG> routine changes the definition of a color-
213 pair. It takes three arguments: the number of the color-
214 pair to be changed, the foreground color number, and the
215 background color number. For portable applications:
217 <STRONG>o</STRONG> The first argument must be a legal color pair value.
218 If default colors are used (see <STRONG>use_default_colors</STRONG>)
219 the upper limit is adjusted to allow for extra pairs
220 which use a default color in foreground and/or back-
223 <STRONG>o</STRONG> The second and third arguments must be legal color
226 If the color-pair was previously initialized, the screen
227 is refreshed and all occurrences of that color-pair are
228 changed to the new definition.
230 As an extension, ncurses allows you to set color pair <STRONG>0</STRONG>
231 via the <STRONG>assume_default_colors</STRONG> routine, or to specify the
232 use of default colors (color number <STRONG>-1</STRONG>) if you first in-
233 voke the <STRONG>use_default_colors</STRONG> routine.
235 The <STRONG>init_color</STRONG> routine changes the definition of a color.
236 It takes four arguments: the number of the color to be
237 changed followed by three RGB values (for the amounts of
238 red, green, and blue components). The first argument must
239 be a legal color value; default colors are not allowed
240 here. (See the section <STRONG>Colors</STRONG> for the default color in-
241 dex.) Each of the last three arguments must be a value in
242 the range <STRONG>0</STRONG> through <STRONG>1000</STRONG>. When <STRONG>init_color</STRONG> is used, all
243 occurrences of that color on the screen immediately change
244 to the new definition.
246 The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
247 <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
248 returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
249 independent programs. For example, a programmer can use
250 it to decide whether to use color or some other video at-
253 The <STRONG>can_change_color</STRONG> routine requires no arguments. It
254 returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
255 change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
256 routine facilitates writing terminal-independent programs.
258 The <STRONG>color_content</STRONG> routine gives programmers a way to find
259 the intensity of the red, green, and blue (RGB) components
260 in a color. It requires four arguments: the color number,
261 and three addresses of <STRONG>short</STRONG>s for storing the information
262 about the amounts of red, green, and blue components in
263 the given color. The first argument must be a legal color
264 value, i.e., <STRONG>0</STRONG> through <STRONG>COLORS-1</STRONG>, inclusive. The values
265 that are stored at the addresses pointed to by the last
266 three arguments are in the range <STRONG>0</STRONG> (no component) through
267 <STRONG>1000</STRONG> (maximum amount of component), inclusive.
269 The <STRONG>pair_content</STRONG> routine allows programmers to find out
270 what colors a given color-pair consists of. It requires
271 three arguments: the color-pair number, and two addresses
272 of <STRONG>short</STRONG>s for storing the foreground and the background
273 color numbers. The first argument must be a legal color
274 value, i.e., in the range <STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclu-
275 sive. The values that are stored at the addresses pointed
276 to by the second and third arguments are in the range <STRONG>0</STRONG>
277 through <STRONG>COLORS</STRONG>, inclusive.
279 <STRONG>PAIR_NUMBER(</STRONG><EM>attrs</EM>) extracts the color value from its <EM>attrs</EM>
280 parameter and returns it as a color pair number. Its in-
281 verse <STRONG>COLOR_PAIR(</STRONG><EM>n</EM><STRONG>)</STRONG> converts a color pair number to an at-
282 tribute. Attributes can hold color pairs in the range 0
283 to 255. If you need a color pair larger than that, you
284 must use functions such as <STRONG>attr_set</STRONG> (which pass the color
285 pair as a separate parameter) rather than the legacy func-
286 tions such as <STRONG>attrset</STRONG>.
289 </PRE><H3><a name="h3-Colors">Colors</a></H3><PRE>
290 In <STRONG><curses.h></STRONG> the following macros are defined. These are
291 the standard colors (ISO-6429). <STRONG>curses</STRONG> also assumes that
292 <STRONG>COLOR_BLACK</STRONG> is the default background color for all termi-
295 <STRONG>COLOR_BLACK</STRONG>
296 <STRONG>COLOR_RED</STRONG>
297 <STRONG>COLOR_GREEN</STRONG>
298 <STRONG>COLOR_YELLOW</STRONG>
299 <STRONG>COLOR_BLUE</STRONG>
300 <STRONG>COLOR_MAGENTA</STRONG>
301 <STRONG>COLOR_CYAN</STRONG>
302 <STRONG>COLOR_WHITE</STRONG>
305 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
306 The routines <STRONG>can_change_color</STRONG> and <STRONG>has_colors</STRONG> return <STRONG>TRUE</STRONG>
307 or <STRONG>FALSE</STRONG>.
309 All other routines return the integer <STRONG>ERR</STRONG> upon failure and
310 an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
311 <STRONG>ERR</STRONG>") upon successful completion.
313 X/Open defines no error conditions. This implementation
314 will return <STRONG>ERR</STRONG> on attempts to use color values outside
315 the range <STRONG>0</STRONG> to COLORS-1 (except for the default colors ex-
316 tension), or use color pairs outside the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG>
317 <STRONG>OR_PAIRS-1</STRONG>. Color values used in <STRONG>init_color</STRONG> must be in
318 the range <STRONG>0</STRONG> to <STRONG>1000</STRONG>. An error is returned from all func-
319 tions if the terminal has not been initialized. An error
320 is returned from secondary functions such as <STRONG>init_pair</STRONG> if
321 <STRONG>start_color</STRONG> was not called.
323 <STRONG>init_color</STRONG>
324 returns an error if the terminal does not support
325 this feature, e.g., if the <STRONG>initialize_color</STRONG> capa-
326 bility is absent from the terminal description.
328 <STRONG>start_color</STRONG>
329 returns an error if the color table cannot be al-
333 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
334 In the <STRONG>ncurses</STRONG> implementation, there is a separate color
335 activation flag, color palette, color pairs table, and as-
336 sociated COLORS and COLOR_PAIRS counts for each screen;
337 the <STRONG>start_color</STRONG> function only affects the current screen.
338 The SVr4/XSI interface is not really designed with this in
339 mind, and historical implementations may use a single
340 shared color palette.
342 Note that setting an implicit background color via a color
343 pair affects only character cells that a character write
344 operation explicitly touches. To change the background
345 color used when parts of a window are blanked by erasing
346 or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
348 Several caveats apply on 386 and 486 machines with VGA-
351 <STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use
352 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
354 <STRONG>o</STRONG> The A_BLINK attribute should in theory cause the back-
355 ground to go bright. This often fails to work, and
356 even some cards for which it mostly works (such as the
357 Paradise and compatibles) do the wrong thing when you
358 try to set a bright "yellow" background (you get a
359 blinking yellow foreground instead).
361 <STRONG>o</STRONG> Color RGB values are not settable.
364 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
365 This implementation satisfies XSI Curses's minimum maxi-
366 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
368 The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
369 ground and background color to support the <STRONG>use_de-</STRONG>
370 <STRONG>fault_colors</STRONG> extension, but only if that routine has been
373 The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
374 color for all terminals can be modified using the <STRONG>as-</STRONG>
375 <STRONG>sume_default_colors</STRONG> extension.
377 This implementation checks the pointers, e.g., for the
378 values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and
379 will treat those as optional parameters when null.
382 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
383 <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>
384 <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>, <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
388 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
392 <li><a href="#h2-NAME">NAME</a></li>
393 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
394 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
396 <li><a href="#h3-Overview">Overview</a></li>
397 <li><a href="#h3-Color-Rendering">Color Rendering</a></li>
398 <li><a href="#h3-Routine-Descriptions">Routine Descriptions</a></li>
399 <li><a href="#h3-Colors">Colors</a></li>
402 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
403 <li><a href="#h2-NOTES">NOTES</a></li>
404 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
405 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>