Manual Pages for UNIX Operating System command usage for man COLOR_PAIRS

X/Open Curses Library Functions        can_change_color(3XCURSES)



NAME
     can_change_color,  color_content,  COLOR_PAIR,   has_colors,
     init_color,     init_pair,     pair_content,    PAIR_NUMBER,
     start_color, COLOR_PAIRS, COLORS - manipulate color informa-
     tion

SYNOPSIS
     cc [ flag... ] file... -I /usr/xpg4/include  -L  /usr/xpg4/lib \
      -R  /usr/xpg4/lib  -lcurses  [ library... ]

     c89 [ flag... ] file... -lcurses [ library... ]

     #include 

     bool can_change_color(void);


     int color_content(short color, short *red, short *green, short *blue);


     int COLOR_PAIR(int n);


     bool has_colors(void);


     int init_color(short color, short red, short green, short blue);


     int init_pair(short pair, short f, short b);


     int pair_content(short pair, short *f, short *b);


     int PAIR_NUMBER(int value);


     int start_color(voidextern int COLOR_PAIRS;

     extern int COLORS;


DESCRIPTION
     These functions manipulate color on terminals  that  support
     color.

   Querying Capabilities
     The has_colors() function indicates whether the terminal  is
     a  color terminal. The can_change_color() function indicates
     whether the terminal is a color terminal on which colors can
     be redefined.



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X/Open Curses Library Functions        can_change_color(3XCURSES)



  Initialization
     The start_color() function must be called to enable  use  of
     colors and before any color manipulation function is called.
     The function initializes eight  basic  colors  (black,  red,
     green,  yellow,  blue, magenta, cyan, and white) that can be
     specified by the color macros (such as COLOR_BLACK)  defined
     in  .  The  initial  appearance of these colors is
     unspecified.


     The function also initializes two global external variables:

         o    COLORS defines the number of colors that the termi-
              nal  supports.  See  Color Identification below. If
              COLORS is 0, the terminal does not support redefin-
              ition  of colors and can_change_color() will return
              FALSE.

         o    COLOR_PAIRS defines the maximum  number  of  color-
              pairs  that the terminal supports. See User-defined
              Color Pairs below.


     The start_color() function also restores the colors  on  the
     terminal  to  terminal-specific  initial values. The initial
     background color is assumed to be black for all terminals.

  Color Identification
     The init_color() function redefines color number  color,  on
     terminals  that  support the redefinition of colors, to have
     the red, green, and blue intensity components  specified  by
     red,  green,  and  blue,  respectively. Calling init_color()
     also changes all occurrences of the specified color  on  the
     screen to the new definition.


     The color_content() function identifies the  intensity  com-
     ponents of color number color. It stores the red, green, and
     blue intensity components of this  color  in  the  addresses
     pointed to by red, green, and blue, respectively.


     For both functions, the color argument must be in the  range
     from  0  to  and  including  COLORS-1. Valid intensity value
     range from 0 (no intensity component) up  to  and  including
     1000 (maximum intensity in that component).

  User-defined Color Pairs
     Calling init_pair() defines or redefines  color-pair  number
     pair to have foreground color f and background color b. Cal-
     ling init_pair() changes any characters that were  displayed
     in the color pair's old definition to the new definition and



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X/Open Curses Library Functions        can_change_color(3XCURSES)



     refreshes the screen.


     After defining  the  color  pair,  the  macro  COLOR_PAIR(n)
     returns  the  value of color pair n. This value is the color
     attribute as it would be extracted from  a  chtype.  Contro-
     versy,  the macro COLOR_NUMBER(value) returns the color pair
     number associated with the color attribute value.


     The pair_content()  retrieves  the  component  colors  of  a
     color-pair  number  pair. It stores the foreground and back-
     ground color numbers in the variables pointed to by f and b,
     respectively.


     With init_pair() and pair_content(), the value of pair  must
     be  in  a range from 0 to and including COLOR_PAIRS-1. Valid
     values for f and b are the range from  0  to  and  including
     COLORS-1.

PARAMETERS
     color    Is the number of the color  for  which  to  provide
              information (0 to  COLORS-1).


     red      Is a pointer to the RGB value for the amount of red
              in color.


     green    Is a pointer to the RGB value  for  the  amount  of
              green in color.


     blue     Is a pointer to the RGB value  for  the  amount  of
              blue in color.


     n        Is the number of a color pair.


     pair     Is the number of the color pair for which  to  pro-
              vide information (1 to  COLOR_PAIRS-1).


     f        Is a pointer to the number of the foreground  color
              (0 to COLORS-1) in pair.


     b        Is a pointer to the number of the background  color
              (0 to COLORS-1) in  pair.




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X/Open Curses Library Functions        can_change_color(3XCURSES)



     value    Is a color attribute value.


RETURN VALUES
     The has_colors() function returns TRUE if the  terminal  can
     manipulate colors. Otherwise, it returns FALSE.


     The can_change_color() function returns TRUE if the terminal
     supports  colors  and  is  able to change their definitions.
     Otherwise, it returns FALSE.


     Upon successful completion, the other functions  return  OK.
     Otherwise, they return ERR.

ERRORS
     No errors are defined.

USAGE
     To use these functions, start_color() must be  called,  usu-
     ally right after initscr(3XCURSES).


     The can_change_color() and has_colors() functions facilitate
     writing  terminal-independent  applications.  For example, a
     programmer can use them to decide whether to  use  color  or
     some other video attribute.


     On color terminals, a typical value of COLORS is 8  and  the
     macros  such  as COLOR_BLACK return a value within the range
     from 0 to and including 7. However, applications cannot rely
     on this to be true.

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

















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X/Open Curses Library Functions        can_change_color(3XCURSES)



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | Unsafe                      |
    |_____________________________|_____________________________|
    | Standard                    | See standards(5).           |
    |_____________________________|_____________________________|


SEE ALSO
     attroff(3XCURSES),  delscreen(3XCURSES),  initscr(3XCURSES),
     libcurses(3XCURSES), attributes(5), standards(5)









































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