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default_colors(3X)					    default_colors(3X)

NAME
       use_default_colors, assume_default_colors - use terminal's default col-
       ors

SYNOPSIS
       #include	<curses.h>

       int use_default_colors(void);
       int assume_default_colors(int fg, int bg);

DESCRIPTION
       The use_default_colors()	and assume_default_colors() functions are  ex-
       tensions	to the curses library.	They are used with terminals that sup-
       port ISO	6429 color, or equivalent.  These terminals allow the applica-
       tion  to	reset color to an unspecified default value (e.g., with	SGR 39
       or SGR 49).

       Applications that paint a colored background over the whole  screen  do
       not  take  advantage  of	 SGR 39	and SGR	49.  Some applications are de-
       signed to work with the default background, using colors	only for text.
       For  example, there are several implementations of the ls program which
       use colors to denote different file types or permissions.  These	"color
       ls"  programs do	not necessarily	modify the background color, typically
       using only the setaf terminfo capability	to set the  foreground	color.
       Full-screen  applications  that	use default colors can achieve similar
       visual effects.

       The first function, use_default_colors()	tells the  curses  library  to
       assign  terminal	 default  foreground/background	colors to color	number
       -1. So init_pair(x,COLOR_RED,-1)	will initialize	pair x as red  on  de-
       fault  background and init_pair(x,-1,COLOR_BLUE)	will initialize	pair x
       as default foreground on	blue.

       The other, assume_default_colors() is a refinement  which  tells	 which
       colors  to  paint for color pair	0.  This function recognizes a special
       color number -1,	which denotes the default terminal color.

       The following are equivalent:
	      use_default_colors();
	      assume_default_colors(-1,-1);

       These are ncurses extensions.  For other	curses implementations,	 color
       number -1 does not mean anything, just as for ncurses before a success-
       ful call	of use_default_colors()	or assume_default_colors().

       Other curses implementations do not  allow  an  application  to	modify
       color  pair  0.	They assume that the background	is COLOR_BLACK,	but do
       not ensure that the color pair 0	is painted to  match  the  assumption.
       If  your	 application  does  not	use either use_default_colors()	or as-
       sume_default_colors() ncurses will paint	a white	foreground (text) with
       black background	for color pair 0.

RETURN VALUE
       These  functions	return the integer ERR upon failure and	OK on success.
       They will fail if either	the terminal does not support the orig_pair or
       orig_colors  capability.	  If  the  initialize_pair  capability	is not
       found, this causes an error as well.

NOTES
       Associated with this extension, the init_pair function accepts negative
       arguments to specify default foreground or background colors.

       The  use_default_colors() function was added to support ded.  This is a
       full-screen application which uses curses to manage only	 part  of  the
       screen.	The bottom portion of the screen, which	is of adjustable size,
       is left uncolored to display the	results	from shell commands.  The  top
       portion	of  the	screen colors filenames	using a	scheme like the	"color
       ls" programs.  Attempting to manage the background color	of the	screen
       for this	application would give unsatisfactory results for a variety of
       reasons.	 This extension	was devised after noting that color xterm (and
       similar	programs) provides a background	color which does not necessar-
       ily correspond to any of	the ANSI colors.  While	a special terminfo en-
       try could be constructed	using nine colors, there was no	mechanism pro-
       vided  within  curses  to  account  for	the  related   orig_pair   and
       back_color_erase	capabilities.

       The  assume_default_colors()  function  was  added to solve a different
       problem:	support	for applications which would use environment variables
       and  other configuration	to bypass curses' notion of the	terminal's de-
       fault colors, setting specific values.

PORTABILITY
       These routines are specific to ncurses.	They  were  not	 supported  on
       Version 7, BSD or System	V implementations.  It is recommended that any
       code depending on them be conditioned using NCURSES_VERSION.

SEE ALSO
       curs_color(3X), ded(1).

AUTHOR
       Thomas Dickey (from an analysis of the requirements for color xterm for
       XFree86 3.1.2C, February	1996).

							    default_colors(3X)

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

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