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| <H1 class="no-header">curs_color 3x</H1> |
| <PRE> |
| <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> |
| |
| |
| |
| |
| </PRE> |
| <H2><a name="h2-NAME">NAME</a></H2><PRE> |
| <STRONG>start_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>, <STRONG>has_colors</STRONG>, |
| <STRONG>can_change_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>, <STRONG>COLOR_PAIR</STRONG> |
| - <STRONG>curses</STRONG> color manipulation routines |
| |
| |
| </PRE> |
| <H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE> |
| <STRONG>#</STRONG> <STRONG>include</STRONG> <STRONG><curses.h></STRONG> |
| |
| <STRONG>int</STRONG> <STRONG>start_color(void);</STRONG> |
| <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG> |
| <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> |
| <STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG> |
| <STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG> |
| <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> |
| <STRONG>*b);</STRONG> |
| <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG> |
| |
| |
| </PRE> |
| <H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE> |
| |
| </PRE> |
| <H3><a name="h3-Overview">Overview</a></H3><PRE> |
| <STRONG>curses</STRONG> supports color attributes on terminals with that |
| capability. To use these routines <STRONG>start_color</STRONG> must be |
| called, usually right after <STRONG>initscr</STRONG>. Colors are always |
| used in pairs (referred to as color-pairs). A color-pair |
| consists of a foreground color (for characters) and a |
| background color (for the blank field on which the charac- |
| ters are displayed). A programmer initializes a color- |
| pair with the routine <STRONG>init_pair</STRONG>. After it has been ini- |
| tialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>), a macro defined in <STRONG><curses.h></STRONG>, |
| can be used as a new video attribute. |
| |
| If a terminal is capable of redefining colors, the pro- |
| grammer can use the routine <STRONG>init_color</STRONG> to change the defi- |
| nition of a color. The routines <STRONG>has_colors</STRONG> and |
| <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending on |
| whether the terminal has color capabilities and whether |
| the programmer can change the colors. The routine <STRONG>col-</STRONG> |
| <STRONG>or_content</STRONG> allows a programmer to extract the amounts of |
| red, green, and blue components in an initialized color. |
| The routine <STRONG>pair_content</STRONG> allows a programmer to find out |
| how a given color-pair is currently defined. |
| |
| |
| </PRE> |
| <H3><a name="h3-Color-Rendering">Color Rendering</a></H3><PRE> |
| The <STRONG>curses</STRONG> library combines these inputs to produce the |
| actual foreground and background colors shown on the |
| screen: |
| |
| <STRONG>o</STRONG> per-character video attributes (e.g., via <STRONG>waddch</STRONG>), |
| |
| <STRONG>o</STRONG> the window attribute (e.g., by <STRONG>wattrset</STRONG>), and |
| |
| <STRONG>o</STRONG> the background character (e.g., <STRONG>wbkgdset</STRONG>). |
| |
| Per-character and window attributes are usually set by a |
| parameter containing video attributes including a <STRONG>COL-</STRONG> |
| <STRONG>OR_PAIR</STRONG> value. Some functions such as <STRONG>wattr_set</STRONG> use a |
| separate parameter which is the color pair number. |
| |
| The background character is a special case: it includes a |
| character value, just as if it were passed to <STRONG>waddch</STRONG>. |
| |
| The <STRONG>curses</STRONG> library does the actual work of combining these |
| color pairs in an internal function called from <STRONG>waddch</STRONG>: |
| |
| <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>blank</EM>, and it us- |
| es the special color pair 0, |
| |
| <STRONG>o</STRONG> <STRONG>curses</STRONG> next checks the window attribute. |
| |
| <STRONG>o</STRONG> If the window attribute does not use color pair 0, |
| <STRONG>curses</STRONG> uses the color pair from the window at- |
| tribute. |
| |
| <STRONG>o</STRONG> Otherwise, <STRONG>curses</STRONG> uses the background character. |
| |
| <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>not</EM> <EM>blank</EM>, or it |
| does not use the special color pair 0, <STRONG>curses</STRONG> prefers |
| the color pair from the parameter, if it is nonzero. |
| Otherwise, it tries the window attribute next, and fi- |
| nally the background character. |
| |
| Some <STRONG>curses</STRONG> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those |
| do not combine its parameter with a color pair. Conse- |
| quently those calls use only the window attribute or the |
| background character. |
| |
| |
| </PRE> |
| <H3><a name="h3-Routine-Descriptions">Routine Descriptions</a></H3><PRE> |
| The <STRONG>start_color</STRONG> routine requires no arguments. It must be |
| called if the programmer wants to use colors, and before |
| any other color manipulation routine is called. It is |
| good practice to call this routine right after <STRONG>initscr</STRONG>. |
| <STRONG>start_color</STRONG> does this: |
| |
| <STRONG>o</STRONG> It initializes two global variables, <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG> |
| <STRONG>OR_PAIRS</STRONG> (respectively defining the maximum number of |
| colors and color-pairs the terminal can support). |
| |
| <STRONG>o</STRONG> It initializes the special color pair <STRONG>0</STRONG> to the default |
| foreground and background colors. No other color |
| pairs are initialized. |
| |
| <STRONG>o</STRONG> It restores the colors on the terminal to the values |
| they had when the terminal was just turned on. |
| |
| <STRONG>o</STRONG> If the terminal supports the <STRONG>initc</STRONG> (<STRONG>initialize_color</STRONG>) |
| capability, <STRONG>start_color</STRONG> initializes its internal table |
| representing the red, green and blue components of the |
| color palette. |
| |
| The components depend on whether the terminal uses CGA |
| (aka "ANSI") or HLS (i.e., the <STRONG>hls</STRONG> (<STRONG>hue_lightness_sat-</STRONG> |
| <STRONG>uration</STRONG>) capability is set). The table is initialized |
| first for eight basic colors (black, red, green, yel- |
| low, blue, magenta, cyan, and white), and after that |
| (if the terminal supports more than eight colors) the |
| components are initialized to <STRONG>1000</STRONG>. |
| |
| <STRONG>start_color</STRONG> does not attempt to set the terminal's |
| color palette to match its built-in table. An appli- |
| cation may use <STRONG>init_color</STRONG> to alter the internal table |
| along with the terminal's color. |
| |
| These limits apply to color values and color pairs. Val- |
| ues outside these limits are not legal, and may result in |
| a runtime error: |
| |
| <STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_col-</STRONG> |
| <STRONG>ors</STRONG> capability, which is typically a signed 16-bit in- |
| teger (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>). |
| |
| <STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG> |
| <STRONG>ORS-1</STRONG>, inclusive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>). |
| |
| <STRONG>o</STRONG> a special color value <STRONG>-1</STRONG> is used in certain extended |
| functions to denote the <EM>default</EM> <EM>color</EM> (see <STRONG>use_de-</STRONG> |
| <STRONG>fault_colors</STRONG>). |
| |
| <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's |
| <STRONG>max_pairs</STRONG> capability, which is typically a signed |
| 16-bit integer (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>). |
| |
| <STRONG>o</STRONG> legal color pair values are in the range <STRONG>1</STRONG> to <STRONG>COL-</STRONG> |
| <STRONG>OR_PAIRS-1</STRONG>, inclusive. |
| |
| <STRONG>o</STRONG> color pair <STRONG>0</STRONG> is special; it denotes "no color". |
| |
| Color pair <STRONG>0</STRONG> is assumed to be white on black, but is |
| actually whatever the terminal implements before color |
| is initialized. It cannot be modified by the applica- |
| tion. |
| |
| The <STRONG>init_pair</STRONG> routine changes the definition of a color- |
| pair. It takes three arguments: the number of the color- |
| pair to be changed, the foreground color number, and the |
| background color number. For portable applications: |
| |
| <STRONG>o</STRONG> The first argument must be a legal color pair value. |
| If default colors are used (see <STRONG>use_default_colors</STRONG>) |
| the upper limit is adjusted to allow for extra pairs |
| which use a default color in foreground and/or back- |
| ground. |
| |
| <STRONG>o</STRONG> The second and third arguments must be legal color |
| values. |
| |
| If the color-pair was previously initialized, the screen |
| is refreshed and all occurrences of that color-pair are |
| changed to the new definition. |
| |
| As an extension, ncurses allows you to set color pair <STRONG>0</STRONG> |
| via the <STRONG>assume_default_colors</STRONG> routine, or to specify the |
| use of default colors (color number <STRONG>-1</STRONG>) if you first in- |
| voke the <STRONG>use_default_colors</STRONG> routine. |
| |
| The <STRONG>init_color</STRONG> routine changes the definition of a color. |
| It takes four arguments: the number of the color to be |
| changed followed by three RGB values (for the amounts of |
| red, green, and blue components). The first argument must |
| be a legal color value; default colors are not allowed |
| here. (See the section <STRONG>Colors</STRONG> for the default color in- |
| dex.) Each of the last three arguments must be a value in |
| the range <STRONG>0</STRONG> through <STRONG>1000</STRONG>. When <STRONG>init_color</STRONG> is used, all |
| occurrences of that color on the screen immediately change |
| to the new definition. |
| |
| The <STRONG>has_colors</STRONG> routine requires no arguments. It returns |
| <STRONG>TRUE</STRONG> if the terminal can manipulate colors; otherwise, it |
| returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal- |
| independent programs. For example, a programmer can use |
| it to decide whether to use color or some other video at- |
| tribute. |
| |
| The <STRONG>can_change_color</STRONG> routine requires no arguments. It |
| returns <STRONG>TRUE</STRONG> if the terminal supports colors and can |
| change their definitions; other, it returns <STRONG>FALSE</STRONG>. This |
| routine facilitates writing terminal-independent programs. |
| |
| The <STRONG>color_content</STRONG> routine gives programmers a way to find |
| the intensity of the red, green, and blue (RGB) components |
| in a color. It requires four arguments: the color number, |
| and three addresses of <STRONG>short</STRONG>s for storing the information |
| about the amounts of red, green, and blue components in |
| the given color. The first argument must be a legal color |
| value, i.e., <STRONG>0</STRONG> through <STRONG>COLORS-1</STRONG>, inclusive. The values |
| that are stored at the addresses pointed to by the last |
| three arguments are in the range <STRONG>0</STRONG> (no component) through |
| <STRONG>1000</STRONG> (maximum amount of component), inclusive. |
| |
| The <STRONG>pair_content</STRONG> routine allows programmers to find out |
| what colors a given color-pair consists of. It requires |
| three arguments: the color-pair number, and two addresses |
| of <STRONG>short</STRONG>s for storing the foreground and the background |
| color numbers. The first argument must be a legal color |
| value, i.e., in the range <STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclu- |
| sive. The values that are stored at the addresses pointed |
| to by the second and third arguments are in the range <STRONG>0</STRONG> |
| through <STRONG>COLORS</STRONG>, inclusive. |
| |
| |
| </PRE> |
| <H3><a name="h3-Colors">Colors</a></H3><PRE> |
| In <STRONG><curses.h></STRONG> the following macros are defined. These are |
| the standard colors (ISO-6429). <STRONG>curses</STRONG> also assumes that |
| <STRONG>COLOR_BLACK</STRONG> is the default background color for all termi- |
| nals. |
| |
| <STRONG>COLOR_BLACK</STRONG> |
| <STRONG>COLOR_RED</STRONG> |
| <STRONG>COLOR_GREEN</STRONG> |
| <STRONG>COLOR_YELLOW</STRONG> |
| <STRONG>COLOR_BLUE</STRONG> |
| <STRONG>COLOR_MAGENTA</STRONG> |
| <STRONG>COLOR_CYAN</STRONG> |
| <STRONG>COLOR_WHITE</STRONG> |
| |
| |
| </PRE> |
| <H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE> |
| The routines <STRONG>can_change_color()</STRONG> and <STRONG>has_colors()</STRONG> return |
| <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>. |
| |
| All other routines return the integer <STRONG>ERR</STRONG> upon failure and |
| an <STRONG>OK</STRONG> (SVr4 specifies only "an integer value other than |
| <STRONG>ERR</STRONG>") upon successful completion. |
| |
| X/Open defines no error conditions. This implementation |
| will return <STRONG>ERR</STRONG> on attempts to use color values outside |
| the range <STRONG>0</STRONG> to COLORS-1 (except for the default colors ex- |
| tension), or use color pairs outside the range <STRONG>0</STRONG> to <STRONG>COL-</STRONG> |
| <STRONG>OR_PAIRS-1</STRONG>. Color values used in <STRONG>init_color</STRONG> must be in |
| the range <STRONG>0</STRONG> to <STRONG>1000</STRONG>. An error is returned from all func- |
| tions if the terminal has not been initialized. An error |
| is returned from secondary functions such as <STRONG>init_pair</STRONG> if |
| <STRONG>start_color</STRONG> was not called. |
| |
| <STRONG>init_color</STRONG> |
| returns an error if the terminal does not support |
| this feature, e.g., if the <EM>initialize</EM><STRONG>_</STRONG><EM>color</EM> capa- |
| bility is absent from the terminal description. |
| |
| <STRONG>start_color</STRONG> |
| returns an error if the color table cannot be al- |
| located. |
| |
| |
| </PRE> |
| <H2><a name="h2-NOTES">NOTES</a></H2><PRE> |
| In the <EM>ncurses</EM> implementation, there is a separate color |
| activation flag, color palette, color pairs table, and as- |
| sociated COLORS and COLOR_PAIRS counts for each screen; |
| the <STRONG>start_color</STRONG> function only affects the current screen. |
| The SVr4/XSI interface is not really designed with this in |
| mind, and historical implementations may use a single |
| shared color palette. |
| |
| Note that setting an implicit background color via a color |
| pair affects only character cells that a character write |
| operation explicitly touches. To change the background |
| color used when parts of a window are blanked by erasing |
| or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>. |
| |
| Several caveats apply on 386 and 486 machines with VGA- |
| compatible graphics: |
| |
| <STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use |
| COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute. |
| |
| <STRONG>o</STRONG> The A_BLINK attribute should in theory cause the back- |
| ground to go bright. This often fails to work, and |
| even some cards for which it mostly works (such as the |
| Paradise and compatibles) do the wrong thing when you |
| try to set a bright "yellow" background (you get a |
| blinking yellow foreground instead). |
| |
| <STRONG>o</STRONG> Color RGB values are not settable. |
| |
| |
| </PRE> |
| <H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> |
| This implementation satisfies XSI Curses's minimum maxi- |
| mums for <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>. |
| |
| The <STRONG>init_pair</STRONG> routine accepts negative values of fore- |
| ground and background color to support the <STRONG>use_de-</STRONG> |
| <STRONG>fault_colors</STRONG> extension, but only if that routine has been |
| first invoked. |
| |
| The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background |
| color for all terminals can be modified using the <STRONG>as-</STRONG> |
| <STRONG>sume_default_colors</STRONG> extension. |
| |
| This implementation checks the pointers, e.g., for the |
| values returned by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and |
| will treat those as optional parameters when null. |
| |
| |
| </PRE> |
| <H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> |
| <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> |
| <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>, <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG> |
| |
| |
| |
| <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> |
| </PRE> |
| <div class="nav"> |
| <ul> |
| <li><a href="#h2-NAME">NAME</a></li> |
| <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li> |
| <li><a href="#h2-DESCRIPTION">DESCRIPTION</a> |
| <ul> |
| <li><a href="#h3-Overview">Overview</a></li> |
| <li><a href="#h3-Color-Rendering">Color Rendering</a></li> |
| <li><a href="#h3-Routine-Descriptions">Routine Descriptions</a></li> |
| <li><a href="#h3-Colors">Colors</a></li> |
| </ul> |
| </li> |
| <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li> |
| <li><a href="#h2-NOTES">NOTES</a></li> |
| <li><a href="#h2-PORTABILITY">PORTABILITY</a></li> |
| <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> |
| </ul> |
| </div> |
| </BODY> |
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