# default_colors

## 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 successful 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.
    


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