`background_valid', and `background_transparent' fields.
(image_background, image_background_transparent): New declarations.
(IMAGE_BACKGROUND, IMAGE_BACKGROUND_TRANSPARENT): New macros.
-
* xfns.c (image_background, image_background_transparent)
(four_corners_best): New functions.
(xpm_format, png_format, jpeg_format, tiff_format, gif_format)
(enum gs_keyword_index): Add GS_BACKGROUND.
(pbm_load, png_load, jpeg_load, tiff_load, gif_load):
Pre-calculate image background color where necessary.
-
* xterm.c (x_setup_relief_colors): Use `IMAGE_BACKGROUND' and
`IMAGE_BACKGROUND_TRANSPARENT' to calculate the correct background
color to use for image glyph reliefs.