+ These limits apply to color values and color pairs. Values 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_colors</STRONG> capabili-
+ ty, (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>COLORS-1</STRONG>, inclu-
+ sive (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_default_colors</STRONG>).
+
+ <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's <STRONG>max_pairs</STRONG> capa-
+ bility, (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>COLOR_PAIRS-1</STRONG>, inclu-
+ sive.
+
+ <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 what-
+ ever the terminal implements before color is initialized. It can-
+ not be modified by the application.
+
+
+</PRE><H3><a name="h3-has_colors">has_colors</a></H3><PRE>
+ 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 rou-
+ tine facilitates writing terminal-independent programs. For example, a
+ programmer can use it to decide whether to use color or some other
+ video attribute.
+
+
+</PRE><H3><a name="h3-can_change_color">can_change_color</a></H3><PRE>
+ 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-indepen-
+ dent programs.
+
+
+</PRE><H3><a name="h3-init_pair">init_pair</a></H3><PRE>
+ 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 fore-
+ ground color number, and the background color number. For portable ap-
+ plications:
+
+ <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 adjust-
+ ed to allow for extra pairs which use a default color in foreground
+ and/or background.
+
+ <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 defini-
+ tion.
+
+ As an extension, ncurses allows you to set color pair <STRONG>0</STRONG> via the <STRONG>as-</STRONG>
+ <STRONG><A HREF="assume_default_colors.3x.html">sume_default_colors(3x)</A></STRONG> routine, or to specify the use of default col-
+ ors (color number <STRONG>-1</STRONG>) if you first invoke the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG>
+ routine.
+
+ The extension <STRONG>reset_color_pairs</STRONG> tells ncurses to discard all of the
+ color-pair information which was set with <STRONG>init_pair</STRONG>. It also touches
+ the current- and standard-screens, allowing an application to switch
+ color palettes rapidly.
+
+
+</PRE><H3><a name="h3-init_color">init_color</a></H3><PRE>
+ 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).
+
+ <STRONG>o</STRONG> 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
+ index.)
+
+ <STRONG>o</STRONG> 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.
+
+
+</PRE><H3><a name="h3-color_content">color_content</a></H3><PRE>
+ 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 com-
+ ponents in the given color.
+
+ <STRONG>o</STRONG> The first argument must be a legal color value, i.e., <STRONG>0</STRONG> through
+ <STRONG>COLORS-1</STRONG>, inclusive.
+
+ <STRONG>o</STRONG> 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.
+
+
+</PRE><H3><a name="h3-pair_content">pair_content</a></H3><PRE>
+ 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.
+
+ <STRONG>o</STRONG> The first argument must be a legal color value, i.e., in the range
+ <STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclusive.
+
+ <STRONG>o</STRONG> The values that are stored at the addresses pointed to by the sec-
+ ond and third arguments are in the range <STRONG>0</STRONG> through <STRONG>COLORS</STRONG>, inclu-
+ sive.
+
+
+</PRE><H3><a name="h3-PAIR_NUMBER">PAIR_NUMBER</a></H3><PRE>
+ <STRONG>PAIR_NUMBER(</STRONG><EM>attrs</EM>) extracts the color value from its <EM>attrs</EM> parameter
+ and returns it as a color pair number.
+
+
+</PRE><H3><a name="h3-COLOR_PAIR">COLOR_PAIR</a></H3><PRE>
+ Its inverse <STRONG>COLOR_PAIR(</STRONG><EM>n</EM><STRONG>)</STRONG> converts a color pair number to an attribute.
+ Attributes can hold color pairs in the range 0 to 255. If you need a
+ color pair larger than that, you must use functions such as <STRONG>attr_set</STRONG>
+ (which pass the color pair as a separate parameter) rather than the
+ legacy functions such as <STRONG>attrset</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 com-
+ pletion.
+
+ 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 <STRONG>COLORS</STRONG>-1
+ (except for the default colors extension), or use color pairs outside
+ the range <STRONG>0</STRONG> to <STRONG>COLOR_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 functions 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 <STRONG>initialize_color</STRONG> capability is absent from the
+ terminal description.
+
+ <STRONG>start_color</STRONG>
+ returns an error if the color table cannot be allocated.
+
+
+</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
+ In the <STRONG>ncurses</STRONG> implementation, there is a separate color activation
+ flag, color palette, color pairs table, and associated <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG>
+ <STRONG>OR_PAIRS</STRONG> 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.
+
+ 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 older x86 machines (e.g., i386, i486) 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 background 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 maximums for <STRONG>COLORS</STRONG>
+ and <STRONG>COLOR_PAIRS</STRONG>.
+
+ The <STRONG>init_pair</STRONG> routine accepts negative values of foreground and back-
+ ground color to support the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></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><A HREF="default_colors.3x.html">assume_default_colors(3x)</A></STRONG> exten-
+ sion.
+
+ 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 pa-
+ rameters when null.
+
+ X/Open Curses does not specify a limit for the number of colors and
+ color pairs which a terminal can support. However, in its use of <STRONG>short</STRONG>
+ for the parameters, it carries over SVr4's implementation detail for
+ the compiled terminfo database, which uses signed 16-bit numbers. This
+ implementation provides extended versions of those functions which use
+ <STRONG>short</STRONG> parameters, allowing applications to use larger color- and pair-
+ numbers.
+
+ The <STRONG>reset_color_pairs</STRONG> function is an extension of ncurses.
+
+
+</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><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG>de-</STRONG>
+ <STRONG><A HREF="default_colors.3x.html">fault_colors(3x)</A></STRONG>