[cairo] pixman BGRA support

[kettenis at openbsd.org]

> From: Soeren Sandmann <sandmann at daimi.au.dk>
> Date: 24 Mar 2009 19:34:23 +0100
> 
> Mark Kettenis <kettenis at openbsd.org> writes:
> 
> > Hi,
> > 
> > I'm trying to make Xorg work on a Tech Source Raptor GFX-8M graphics
> > card on OpenBSD/sparc64.  This card is based on the Number 9 I128-II
> > chip, which has a little-endian framebuffer, that essentially uses
> > ARGB pixel representation.  However, since I'm using it on a
> > big-endian machine, the pixel representation as seen by the host CPU
> > is BGRA.  As far as I can tell, the graphics hardware does not support
> > byte swapping in hardware like the ATI cards that Sun used in many of
> > their PCI framebuffers.
> > 
> > The diff below adds BGRA support to pixman.  I have diffs for Xrender
> > and cairo as well, that make firefox work fine (without them the most
> > obvious problem is that text seems to be drawn on a yellow
> > background).
> 
> Thanks, pushed.

Thanks a lot.

With that being in, here's the code I have for cairo.  There are two
issues here:

* This probably needs some #if PIXMAN_VERSION >= PIXMAN_VERSION_ENCODE(X,Y,Z)
  sprinkled into it.  Not sure what those X, Y and Z need to be though.

* To distinguish between ABGR and BGRA pixel formats my code checks
  whether the LSB of masks->red_mask is set.  It seems to me, that
  should be the case for all ABGR formats, but I'm not absolutely sure
  here.

Mark


diff --git a/src/cairo-image-surface.c b/src/cairo-image-surface.c
index e9e544d..fe6f9b7 100644
--- a/src/cairo-image-surface.c
+++ b/src/cairo-image-surface.c
@@ -77,6 +77,7 @@ _cairo_content_from_pixman_format (pixman_format_code_t pixman_format)
     switch (pixman_format) {
     case PIXMAN_a8r8g8b8:
     case PIXMAN_a8b8g8r8:
+    case PIXMAN_b8g8r8a8:
     case PIXMAN_a1r5g5b5:
     case PIXMAN_a1b5g5r5:
     case PIXMAN_a4r4g4b4:
@@ -91,6 +92,7 @@ _cairo_content_from_pixman_format (pixman_format_code_t pixman_format)
 	return CAIRO_CONTENT_COLOR_ALPHA;
     case PIXMAN_x8r8g8b8:
     case PIXMAN_x8b8g8r8:
+    case PIXMAN_b8g8r8x8:
     case PIXMAN_r8g8b8:
     case PIXMAN_b8g8r8:
     case PIXMAN_r5g6b5:
@@ -171,8 +173,10 @@ _pixman_format_from_masks (cairo_format_masks_t *masks,
     if (masks->red_mask) {
 	if (masks->red_mask > masks->blue_mask)
 	    format_type = PIXMAN_TYPE_ARGB;
-	else
+	else if (masks->red_mask & 0x1)
 	    format_type = PIXMAN_TYPE_ABGR;
+	else
+	    format_type = PIXMAN_TYPE_BGRA;
     } else if (masks->alpha_mask) {
 	format_type = PIXMAN_TYPE_A;
     } else {
@@ -232,6 +236,12 @@ _pixman_format_to_masks (pixman_format_code_t	 format,
         masks->green_mask = MASK (g) << (r);
         masks->red_mask   = MASK (r);
         return;
+    case PIXMAN_TYPE_BGRA:
+        masks->alpha_mask = MASK (a);
+        masks->blue_mask  = MASK (b) << (masks->bpp - b);
+        masks->green_mask = MASK (g) << (masks->bpp - b - g);
+        masks->red_mask   = MASK (r) << (masks->bpp - b - g - r);
+        return;
     case PIXMAN_TYPE_A:
         masks->alpha_mask = MASK (a);
         masks->red_mask   = 0;