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30 * @Id: curs_color.3x,v 1.27 2005/05/15 16:55:36 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. If a terminal is
81 capable of redefining colors, the programmer can use the
82 routine <STRONG>init_color</STRONG> to change the definition of a color.
83 The routines <STRONG>has_colors</STRONG> and <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG>
84 or <STRONG>FALSE</STRONG>, depending on whether the terminal has color ca-
85 pabilities and whether the programmer can change the col-
86 ors. The routine <STRONG>color_content</STRONG> allows a programmer to ex-
87 tract the amounts of red, green, and blue components in an
88 initialized color. The routine <STRONG>pair_content</STRONG> allows a pro-
89 grammer to find out how a given color-pair is currently
92 <STRONG>Routine</STRONG> <STRONG>Descriptions</STRONG>
93 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
94 called if the programmer wants to use colors, and before
95 any other color manipulation routine is called. It is
96 good practice to call this routine right after <STRONG>initscr</STRONG>.
97 <STRONG>start_color</STRONG> initializes eight basic colors (black, red,
98 green, yellow, blue, magenta, cyan, and white), and two
99 global variables, <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG> (respectively
100 defining the maximum number of colors and color-pairs the
101 terminal can support). It also restores the colors on the
102 terminal to the values they had when the terminal was just
103 turned on. The <STRONG>init_pair</STRONG> routine changes the definition
104 of a color-pair. It takes three arguments: the number of
105 the color-pair to be changed, the foreground color number,
106 and the background color number. For portable applica-
109 - The value of the first argument must be between <STRONG>1</STRONG> and
110 <STRONG>COLOR_PAIRS-1</STRONG>.
112 - The value of the second and third arguments must be
113 between 0 and <STRONG>COLORS</STRONG>. Color pair 0 is assumed to be
114 white on black, but is actually whatever the terminal
115 implements before color is initialized. It cannot be
116 modified by the application.
118 If the color-pair was previously initialized, the screen
119 is refreshed and all occurrences of that color-pair are
120 changed to the new definition. As an extension, ncurses
121 allows you to set color pair 0 via the <STRONG>assume_default_col-</STRONG>
122 <STRONG>ors</STRONG> routine, or to specify the use of default colors (col-
123 or number <STRONG>-1</STRONG>) if you first invoke the <STRONG>use_default_colors</STRONG>
124 routine. The <STRONG>init_color</STRONG> routine changes the definition of
125 a color. It takes four arguments: the number of the color
126 to be changed followed by three RGB values (for the
127 amounts of red, green, and blue components). The value of
128 the first argument must be between <STRONG>0</STRONG> and <STRONG>COLORS</STRONG>. (See the
129 section <STRONG>Colors</STRONG> for the default color index.) Each of the
130 last three arguments must be a value between 0 and 1000.
131 When <STRONG>init_color</STRONG> is used, all occurrences of that color on
132 the screen immediately change to the new definition. The
133 <STRONG>has_colors</STRONG> routine requires no arguments. It returns <STRONG>TRUE</STRONG>
134 if the terminal can manipulate colors; otherwise, it re-
135 turns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
136 independent programs. For example, a programmer can use
137 it to decide whether to use color or some other video at-
138 tribute. The <STRONG>can_change_color</STRONG> routine requires no argu-
139 ments. It returns <STRONG>TRUE</STRONG> if the terminal supports colors
140 and can change their definitions; other, it returns <STRONG>FALSE</STRONG>.
141 This routine facilitates writing terminal-independent pro-
142 grams. The <STRONG>color_content</STRONG> routine gives programmers a way
143 to find the intensity of the red, green, and blue (RGB)
144 components in a color. It requires four arguments: the
145 color number, and three addresses of <STRONG>short</STRONG>s for storing
146 the information about the amounts of red, green, and blue
147 components in the given color. The value of the first ar-
148 gument must be between 0 and <STRONG>COLORS</STRONG>. The values that are
149 stored at the addresses pointed to by the last three argu-
150 ments are between 0 (no component) and 1000 (maximum
151 amount of component). The <STRONG>pair_content</STRONG> routine allows
152 programmers to find out what colors a given color-pair
153 consists of. It requires three arguments: the color-pair
154 number, and two addresses of <STRONG>short</STRONG>s for storing the fore-
155 ground and the background color numbers. The value of the
156 first argument must be between 1 and <STRONG>COLOR_PAIRS-1</STRONG>. The
157 values that are stored at the addresses pointed to by the
158 second and third arguments are between 0 and <STRONG>COLORS</STRONG>.
160 <STRONG>Colors</STRONG>
161 In <STRONG><curses.h></STRONG> the following macros are defined. These are
162 the default colors. <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
163 is the default background color for all terminals.
164 <STRONG>COLOR_BLACK</STRONG>
165 <STRONG>COLOR_RED</STRONG>
166 <STRONG>COLOR_GREEN</STRONG>
167 <STRONG>COLOR_YELLOW</STRONG>
168 <STRONG>COLOR_BLUE</STRONG>
169 <STRONG>COLOR_MAGENTA</STRONG>
170 <STRONG>COLOR_CYAN</STRONG>
171 <STRONG>COLOR_WHITE</STRONG>
175 <H2>RETURN VALUE</H2><PRE>
176 The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
177 <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>. All other routines return the integer <STRONG>ERR</STRONG>
178 upon failure and an <STRONG>OK</STRONG> (SVr4 specifies only "an integer
179 value other than <STRONG>ERR</STRONG>") upon successful completion.
181 X/Open defines no error conditions. This implementation
182 will return <STRONG>ERR</STRONG> on attempts to use color values outside
183 the range 0 to COLORS-1 (except for the default colors ex-
184 tension), or use color pairs outside the range 0 to COL-
185 OR_PAIR-1. Color values used in <STRONG>init_color</STRONG> must be in the
186 range 0 to 1000. An error is returned from all functions
187 if the terminal has not been initialized. An error is re-
188 turned from secondary functions such as <STRONG>init_pair</STRONG> if
189 <STRONG>start_color</STRONG> was not called.
191 <STRONG>init_color</STRONG>
192 returns an error if the terminal does not sup-
193 port this feature, e.g., if the <EM>initial-</EM>
194 <EM>ize</EM><STRONG>_</STRONG><EM>color</EM> capability is absent from the termi-
197 <STRONG>start_color</STRONG>
198 returns an error If the color table cannot be
204 In the <EM>ncurses</EM> implementation, there is a separate color
205 activation flag, color palette, color pairs table, and as-
206 sociated COLORS and COLOR_PAIRS counts for each screen;
207 the <STRONG>start_color</STRONG> function only affects the current screen.
208 The SVr4/XSI interface is not really designed with this in
209 mind, and historical implementations may use a single
210 shared color palette. Note that setting an implicit back-
211 ground color via a color pair affects only character cells
212 that a character write operation explicitly touches. To
213 change the background color used when parts of a window
214 are blanked by erasing or scrolling operations, see
215 <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>. Several caveats apply on 386 and 486 ma-
216 chines with VGA-compatible graphics:
218 - COLOR_YELLOW is actually brown. To get yellow, use
219 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
221 - The A_BLINK attribute should in theory cause the
222 background to go bright. This often fails to work,
223 and even some cards for which it mostly works (such
224 as the Paradise and compatibles) do the wrong thing
225 when you try to set a bright "yellow" background (you
226 get a blinking yellow foreground instead).
228 - Color RGB values are not settable.
232 <H2>PORTABILITY</H2><PRE>
233 This implementation satisfies XSI Curses's minimum maxi-
234 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
236 The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
237 ground and background color to support the <STRONG>use_de-</STRONG>
238 <STRONG>fault_colors</STRONG> extension, but only if that routine has been
241 The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
242 color for all terminals can be modified using the <STRONG>as-</STRONG>
243 <STRONG>sume_default_colors</STRONG> extension.
245 This implementation checks the pointers, e.g., for the
246 values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and
247 will treat those as optional parameters when null.
251 <H2>SEE ALSO</H2><PRE>
252 <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>
253 <STRONG><A HREF="default_colors.3x.html">ors(3x)</A></STRONG>
257 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
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