[Linux-fbdev-devel] fb_cmap and transparency

[Geert U. <ge...@li...>]

If a colormap contains no transparency information, fb_set_cmap() calls
fb_setcolreg() with trans = 0. This causes all CLUT entries to be fully
transparent on hardware that does have transparency information in the CLUT
registers.

The following patch solves this problem by changing the default transparency
from 0 (full transparent) to 0xffff (full opaque).

The patch applies to both 2.4.20 and 2.5.65.

--- linux/drivers/video/fbcmap.c.orig	Mon Mar  5 09:29:30 2001
+++ linux/drivers/video/fbcmap.c	Mon Mar 17 17:39:59 2003
@@ -271,7 +271,7 @@
 	    hred = *red;
 	    hgreen = *green;
 	    hblue = *blue;
-	    htransp = transp ? *transp : 0;
+	    htransp = transp ? *transp : 0xffff;
 	} else {
 	    get_user(hred, red);
 	    get_user(hgreen, green);
@@ -279,7 +279,7 @@
 	    if (transp)
 		get_user(htransp, transp);
 	    else
-		htransp = 0;
+		htransp = 0xffff;
 	}
 	red++;
 	green++;

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@li...

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds