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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  fore-ground/background foreground/background
       ground/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  any-thing, anything,
       thing,  just  as  for ncurses before a successful call of use_default_colors() or assume_default_col-ors(). assume_default_colors().
       ors().

       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 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 termi-nal's terminal's
       nal's default colors, setting specific values.

PORTABILITY
       These routines are specific to ncurses.  They were not supported on Version 7, BSD or System V imple-mentations. implementations.
       mentations.   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)