RedHat 9 (Linux i386) - man page for assume_default_colors (redhat section 3X)

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default_colors(3X)							       default_colors(3X)

       use_default_colors, assume_default_colors - use terminal's default colors

       #include <curses.h>

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

       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 pro-
       gram  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  ini-
       tialize 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:

       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

       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_col-
       ors() or assume_default_colors() ncurses will paint a white foreground (text)  with  black
       background for color pair 0.

       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 ini-
       tialize_pair capability is found, this causes an error as well.

       Associated  with  this extension, the init_pair(3X) function accepts negative arguments to
       specify default foreground or background colors.

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

       curs_color(3X), ded(1).

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

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