default_colors(3X)														default_colors(3X)

NAME

       use_default_colors, assume_default_colors - use terminal's default colors

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 extensions to the curses library.  They are used with terminals that
       support ISO 6429 color, or equivalent.  These terminals allow the application 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
       designed 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 default 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  suc-
       cessful 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
       assume_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 necessarily correspond to any of the ANSI colors.  While a  special
       terminfo  entry	could be constructed using nine colors, there was no mechanism provided 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 default 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)