Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
curs_color(3X)							curs_color(3X)

NAME
       start_color, init_pair, init_color, has_colors, can_change_color,
       color_content, pair_content, COLOR_PAIR - curses	color manipulation
       routines

SYNOPSIS
       # include <curses.h>
       int start_color(void);
       int init_pair(short pair, short f, short	b);
       int init_color(short color, short r, short g, short b);
       bool has_colors(void);
       bool can_change_color(void);
       int color_content(short color, short *r,	short *g, short	*b);
       int pair_content(short pair, short *f, short *b);

DESCRIPTION
   Overview
       curses  support color attributes	on terminals with that capability.  To
       use these routines start_color must  be	called,	 usually  right	 after
       initscr.	 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 characters are dis-
       played).	 A  programmer	initializes  a	color-pair  with  the  routine
       init_pair.   After  it has been initialized, COLOR_PAIR(n), a macro de-
       fined in	<curses.h>, can	be used	as a new video attribute.

       If a terminal is	capable	of redefining colors, the programmer  can  use
       the  routine  init_color	to change the definition of a color.  The rou-
       tines has_colors	and can_change_color return TRUE or  FALSE,  depending
       on whether the terminal has color capabilities and whether the program-
       mer can change the colors.  The routine color_content allows a program-
       mer  to	extract	 the  amounts of red, green, and blue components in an
       initialized color.  The routine pair_content  allows  a	programmer  to
       find out	how a given color-pair is currently defined.

   Routine Descriptions
       The  start_color	 routine  requires no arguments.  It must be called if
       the programmer wants to use colors, and before any other	color  manipu-
       lation  routine	is  called.   It is good practice to call this routine
       right  after  initscr.	start_color  initializes  eight	 basic	colors
       (black,	red,  green,  yellow, blue, magenta, cyan, and white), and two
       global variables, COLORS	and  COLOR_PAIRS  (respectively	 defining  the
       maximum number of colors	and color-pairs	the terminal can support).  It
       also restores the colors	on the terminal	to the values  they  had  when
       the terminal was	just turned on.

       The init_pair 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:

       -    The	value of the  first  argument  must  be	 between  1  and  COL-
	    OR_PAIRS-1.

       -    The	 value of the second and third arguments must be between 0 and
	    COLORS.  Color pair	0 is assumed to	be white on black, but is  ac-
	    tually  whatever  the terminal implements before color is initial-
	    ized.  It cannot be	modified by the	application.

       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  0	 via  the  as-
       sume_default_colors  routine,  or  to specify the use of	default	colors
       (color number -1) if you	first invoke the use_default_colors routine.

       The init_color 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
       value  of  the  first  argument must be between 0 and COLORS.  (See the
       section Colors for the default color index.)  Each of  the  last	 three
       arguments must be a value between 0 and 1000.  When init_color is used,
       all occurrences of that color on	the screen immediately change  to  the
       new definition.

       The  has_colors	routine	requires no arguments.	It returns TRUE	if the
       terminal	can manipulate colors; otherwise, it returns FALSE.  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.

       The can_change_color routine requires no	arguments.  It returns TRUE if
       the terminal supports colors and	can change their  definitions;	other,
       it  returns  FALSE.  This routine facilitates writing terminal-indepen-
       dent programs.

       The color_content 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  shorts  for
       storing	the information	about the amounts of red, green, and blue com-
       ponents in the given color.  The	value of the first  argument  must  be
       between	0  and	COLORS.	  The  values that are stored at the addresses
       pointed to by the last three arguments are between 0 (no	component) and
       1000 (maximum amount of component).

       The  pair_content  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 shorts	for storing the	foreground and
       the background color numbers.  The value	of the first argument must  be
       between	1  and	COLOR_PAIRS-1.	 The values that are stored at the ad-
       dresses pointed to by the second	and third arguments are	between	0  and
       COLORS.

   Colors
       In  <curses.h> the following macros are defined.	 These are the default
       colors.	curses also assumes that COLOR_BLACK is	the default background
       color for all terminals.

	     COLOR_BLACK
	     COLOR_RED
	     COLOR_GREEN
	     COLOR_YELLOW
	     COLOR_BLUE
	     COLOR_MAGENTA
	     COLOR_CYAN
	     COLOR_WHITE

RETURN VALUE
       The  routines can_change_color()	and has_colors() return	TRUE or	FALSE.

       All other routines return the integer ERR upon failure and an OK	 (SVr4
       specifies  only "an integer value other than ERR") upon successful com-
       pletion.

       X/Open defines no error conditions.  This  implementation  will	return
       ERR  on	attempts  to  use color	values outside the range 0 to COLORS-1
       (except for the default colors extension), or use color	pairs  outside
       the  range  0 to	COLOR_PAIR-1.  Color values used in init_color 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 returned	from secondary
       functions such as init_pair if start_color was not called.

	      init_color
		   returns an error if the terminal does not support this fea-
		   ture,  e.g.,	 if  the initialize_color capability is	absent
		   from	the terminal description.

	      start_color
		   returns an error If the color table cannot be allocated.

NOTES
       In the ncurses implementation, there is	a  separate  color  activation
       flag,  color palette, color pairs table,	and associated COLORS and COL-
       OR_PAIRS	counts for each	screen;	the start_color	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	touch-
       es.   To	 change	 the  background color used when parts of a window are
       blanked by erasing or scrolling operations, see curs_bkgd(3X).

       Several caveats apply on	 386  and  486	machines  with	VGA-compatible
       graphics:

       -    COLOR_YELLOW  is  actually brown.  To get yellow, use COLOR_YELLOW
	    combined with the A_BOLD 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.

PORTABILITY
       This implementation satisfies XSI Curses's minimum maximums for	COLORS
       and COLOR_PAIRS.

       The  init_pair  routine accepts negative	values of foreground and back-
       ground color to support the use_default_colors extension, but  only  if
       that routine has	been first invoked.

       The assumption that COLOR_BLACK is the default background color for all
       terminals can be	modified using the assume_default_colors extension.

       This implementation checks the pointers,	e.g., for the values  returned
       by color_content	and pair_content, and will treat those as optional pa-
       rameters	when null.

SEE ALSO
       curses(3X), curs_initscr(3X), curs_attr(3X), default_colors(3X)

								curs_color(3X)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=curs_color&sektion=3x&manpath=FreeBSD+10.0-RELEASE>

home | help