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30 * @Id: curs_color.3x,v 1.19 2002/02/16 22:38:32 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 -->
46 <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>,
47 <STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>, <STRONG>COLOR_PAIR</STRONG>
48 - <STRONG>curses</STRONG> color manipulation routines
52 <H2>SYNOPSIS</H2><PRE>
53 <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG><curses.h></STRONG>
54 <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
55 <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
56 <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>
57 <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
58 <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
59 <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>
61 <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
65 <H2>DESCRIPTION</H2><PRE>
66 <STRONG>Overview</STRONG>
67 <STRONG>curses</STRONG> support color attributes on terminals with that
68 capability. To use these routines <STRONG>start_color</STRONG> must be
69 called, usually right after <STRONG>initscr</STRONG>. Colors are always
70 used in pairs (referred to as color-pairs). A color-pair
71 consists of a foreground color (for characters) and a
72 background color (for the blank field on which the charac-
73 ters are displayed). A programmer initializes a color-
74 pair with the routine <STRONG>init_pair</STRONG>. After it has been ini-
75 tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG><curses.h></STRONG>,
76 can be used as a new video attribute.
78 If a terminal is capable of redefining colors, the pro-
79 grammer can use the routine <STRONG>init_color</STRONG> to change the defi-
80 nition of a color. The routines <STRONG>has_colors</STRONG> and
81 <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on
82 whether the terminal has color capabilities and whether
83 the programmer can change the colors. The routine
84 <STRONG>color_content</STRONG> allows a programmer to extract the amounts
85 of red, green, and blue components in an initialized
86 color. The routine <STRONG>pair_content</STRONG> allows a programmer to
87 find out how a given color-pair is currently defined.
89 <STRONG>Routine</STRONG> <STRONG>Descriptions</STRONG>
90 The <STRONG>start_color</STRONG> routine requires no arguments. It must be
91 called if the programmer wants to use colors, and before
92 any other color manipulation routine is called. It is
93 good practice to call this routine right after <STRONG>initscr</STRONG>.
94 <STRONG>start_color</STRONG> initializes eight basic colors (black, red,
95 green, yellow, blue, magenta, cyan, and white), and two
96 global variables, <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG> (respectively
97 defining the maximum number of colors and color-pairs the
98 terminal can support). It also restores the colors on the
99 terminal to the values they had when the terminal was just
102 The <STRONG>init_pair</STRONG> routine changes the definition of a color-
103 pair. It takes three arguments: the number of the color-
104 pair to be changed, the foreground color number, and the
105 background color number. For portable applications:
107 - The value of the first argument must be between <STRONG>1</STRONG> and
108 <STRONG>COLOR_PAIRS-1</STRONG>.
110 - The value of the second and third arguments must be
111 between 0 and <STRONG>COLORS</STRONG> (the 0 color pair is wired to
112 white on black and cannot be changed).
114 If the color-pair was previously initialized, the screen
115 is refreshed and all occurrences of that color-pair are
116 changed to the new definition.
118 As an extension, ncurses allows you to set color pair 0
119 via the <STRONG>assume_default_colors</STRONG> routine, or to specify the
120 use of default colors (color number <STRONG>-1</STRONG>) if you first
121 invoke the <STRONG>use_default_colors</STRONG> routine.
123 The <STRONG>init_color</STRONG> routine changes the definition of a color.
124 It takes four arguments: the number of the color to be
125 changed followed by three RGB values (for the amounts of
126 red, green, and blue components). The value of the first
127 argument must be between <STRONG>0</STRONG> and <STRONG>COLORS</STRONG>. (See the section
128 <STRONG>Colors</STRONG> for the default color index.) Each of the last
129 three arguments must be a value between 0 and 1000. When
130 <STRONG>init_color</STRONG> is used, all occurrences of that color on the
131 screen immediately change to the new definition.
133 The <STRONG>has_colors</STRONG> routine requires no arguments. It returns
134 <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it
135 returns <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
140 The <STRONG>can_change_color</STRONG> routine requires no arguments. It
141 returns <STRONG>TRUE</STRONG> if the terminal supports colors and can
142 change their definitions; other, it returns <STRONG>FALSE</STRONG>. This
143 routine facilitates writing terminal-independent programs.
145 The <STRONG>color_content</STRONG> routine gives programmers a way to find
146 the intensity of the red, green, and blue (RGB) components
147 in a color. It requires four arguments: the color number,
148 and three addresses of <STRONG>short</STRONG>s for storing the information
149 about the amounts of red, green, and blue components in
150 the given color. The value of the first argument must be
151 between 0 and <STRONG>COLORS</STRONG>. The values that are stored at the
152 addresses pointed to by the last three arguments are
153 between 0 (no component) and 1000 (maximum amount of com-
156 The <STRONG>pair_content</STRONG> routine allows programmers to find out
157 what colors a given color-pair consists of. It requires
158 three arguments: the color-pair number, and two addresses
159 of <STRONG>short</STRONG>s for storing the foreground and the background
160 color numbers. The value of the first argument must be
161 between 1 and <STRONG>COLOR_PAIRS-1</STRONG>. The values that are stored
162 at the addresses pointed to by the second and third argu-
163 ments are between 0 and <STRONG>COLORS</STRONG>.
165 <STRONG>Colors</STRONG>
166 In <STRONG><curses.h></STRONG> the following macros are defined. These are
167 the default colors. <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
168 is the default background color for all terminals.
170 <STRONG>COLOR_BLACK</STRONG>
171 <STRONG>COLOR_RED</STRONG>
172 <STRONG>COLOR_GREEN</STRONG>
173 <STRONG>COLOR_YELLOW</STRONG>
174 <STRONG>COLOR_BLUE</STRONG>
175 <STRONG>COLOR_MAGENTA</STRONG>
176 <STRONG>COLOR_CYAN</STRONG>
177 <STRONG>COLOR_WHITE</STRONG>
181 <H2>RETURN VALUE</H2><PRE>
182 The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return
183 <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
185 All other routines return the integer <STRONG>ERR</STRONG> upon failure and
186 an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than
187 <STRONG>ERR</STRONG>") upon successful completion.
192 In the <EM>ncurses</EM> implementation, there is a separate color
193 activation flag, color palette, color pairs table, and
194 associated COLORS and COLOR_PAIRS counts for each screen;
195 the <STRONG>start_color</STRONG> function only affects the current screen.
196 The SVr4/XSI interface is not really designed with this in
197 mind, and historical implementations may use a single
198 shared color palette.
200 Note that setting an implicit background color via a color
201 pair affects only character cells that a character write
202 operation explicitly touches. To change the background
203 color used when parts of a window are blanked by erasing
204 or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
206 Several caveats apply on 386 and 486 machines with VGA-
209 - COLOR_YELLOW is actually brown. To get yellow, use
210 COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.
212 - The A_BLINK attribute should in theory cause the
213 background to go bright. This often fails to work,
214 and even some cards for which it mostly works (such
215 as the Paradise and compatibles) do the wrong thing
216 when you try to set a bright "yellow" background (you
217 get a blinking yellow foreground instead).
219 - Color RGB values are not settable.
223 <H2>PORTABILITY</H2><PRE>
224 This implementation satisfies XSI Curses's minimum maxi-
225 mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
227 The <STRONG>init_pair</STRONG> routine accepts negative values of fore-
228 ground and background color to support the
229 <STRONG>use_default_colors</STRONG> extension, but only if that routine has
232 The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background
233 color for all terminals can be modified using the
234 <STRONG>assume_default_colors</STRONG> extension,
239 <H2>SEE ALSO</H2><PRE>
240 <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>
241 <STRONG><A HREF="default_colors.3x.html">ors(3x)</A></STRONG>
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