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       if the terminal can manipulate colors; otherwise,  it  re-
       turns  <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  argu-
       ments.   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 pro-
       grams.  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 value of the first ar-
       gument must be between 0 and <STRONG>COLORS</STRONG>.  The values that  are
       stored at the addresses pointed to by the last three argu-
       ments are between  0  (no  component)  and  1000  (maximum
       amount  of  component).   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  fore-
       ground and the background color numbers.  The value of the
       first argument must be between 1 and  <STRONG>COLOR_PAIRS-1</STRONG>.   The
       values  that are stored at the addresses pointed to by the
       second and third arguments are between 0 and <STRONG>COLORS</STRONG>.

   <STRONG>Colors</STRONG>
       In <STRONG>&lt;curses.h&gt;</STRONG> the following macros are defined.  These are
       the  default colors.  <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG>
       is the default background color for all terminals.
             <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>RETURN VALUE</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 0 to COLORS-1 (except for the default colors ex-
       tension), or use color pairs outside the range 0  to  COL-
       OR_PAIR-1.  Color values used in <STRONG>init_color</STRONG> must be in the
       range 0 to 1000.  An error is returned from all  functions
       if the terminal has not been initialized.  An error is re-
       turned 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 sup-
                   port  this  feature,  e.g.,  if  the  <EM>initial-</EM>
                   <EM>ize</EM><STRONG>_</STRONG><EM>color</EM> capability is absent from the termi-
                   nal description.

              <STRONG>start_color</STRONG>
                   returns an error If the color table cannot  be
                   allocated.


</PRE>
<H2>NOTES</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 back-
       ground 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  ma-
       chines with VGA-compatible graphics:

       -    COLOR_YELLOW  is  actually brown.  To get yellow, use
            COLOR_YELLOW combined with the <STRONG>A_BOLD</STRONG> attribute.

       -    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).

       -    Color RGB values are not settable.


</PRE>
<H2>PORTABILITY</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>SEE ALSO</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>default_col-</STRONG>
       <STRONG><A HREF="default_colors.3x.html">ors(3x)</A></STRONG>



                                                         <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
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