Re: color-grey-p and black?

[Richard M. Stallman]

Does this patch give good results?

*** xfaces.c    27 Sep 2005 17:58:18 -0400      1.336
--- xfaces.c    27 Sep 2005 23:09:16 -0400      
***************
*** 1477,1483 ****
  
  
  /* Return non-zero if COLOR_NAME is a shade of gray (or white or
!    black) on frame F.  The algorithm is taken from 20.2 faces.el.  */
  
  static int
  face_color_gray_p (f, color_name)
--- 1477,1485 ----
  
  
  /* Return non-zero if COLOR_NAME is a shade of gray (or white or
!    black) on frame F.
! 
!    The criterion implemented here is not a terribly sophisticated one.  */
  
  static int
  face_color_gray_p (f, color_name)
***************
*** 1488,1499 ****
    int gray_p;
  
    if (defined_color (f, color_name, &color, 0))
!     gray_p = ((abs (color.red - color.green)
!              < max (color.red, color.green) / 20)
!             && (abs (color.green - color.blue)
!                 < max (color.green, color.blue) / 20)
!             && (abs (color.blue - color.red)
!                 < max (color.blue, color.red) / 20));
    else
      gray_p = 0;
  
--- 1490,1504 ----
    int gray_p;
  
    if (defined_color (f, color_name, &color, 0))
!     gray_p = (/* Any color sufficiently close to black counts as grey.  */
!             (color.red < 5000 && color.green < 5000 && color.blue < 5000)
!             ||
!             ((abs (color.red - color.green)
!               < max (color.red, color.green) / 20)
!              && (abs (color.green - color.blue)
!                  < max (color.green, color.blue) / 20)
!              && (abs (color.blue - color.red)
!                  < max (color.blue, color.red) / 20)));
    else
      gray_p = 0;