Re: Patches to make GDK draw RGB images to ARGB drawables

[Keith Packard <keithp keithp com>]

Here's a second pass of patches for GDK to deal with ARGB drawables.  This 
replaces the previous patches and suffices to make Metacity actually work 
in the cases I tried.  There may well be more places to fix; I didn't make 
an exhaustive search.

Better patches for metacity will follow to desktop-devel

-keith

Index: gdkrgb.c
===================================================================
RCS file: /cvs/gnome/gtk+/gdk/gdkrgb.c,v
retrieving revision 1.57
diff -u -r1.57 gdkrgb.c
--- gdkrgb.c	6 Mar 2004 03:36:59 -0000	1.57
+++ gdkrgb.c	26 Jun 2004 04:21:53 -0000
@@ -718,6 +718,17 @@
   return image_info;
 }
 
+#define FullMask(depth) ((depth == 32) ? (guint32) ~0 : ((guint32) 1 << (depth)) - 1)
+
+static guint32
+gdk_rgb_info_alpha (GdkRgbInfo *image_info)
+{
+  return (~(image_info->visual->red_mask |
+	    image_info->visual->green_mask |
+	    image_info->visual->blue_mask) & 
+	  FullMask (image_info->visual->depth));
+}
+
 static gulong
 gdk_rgb_xpixel_from_rgb_internal (GdkColormap *colormap,
 				  guint16 r, guint16 g, guint16 b)
@@ -757,6 +768,7 @@
       pixel = (((r >> (16 - image_info->visual->red_prec)) << image_info->visual->red_shift) +
 	       ((g >> (16 - image_info->visual->green_prec)) << image_info->visual->green_shift) +
 	       ((b >> (16 - image_info->visual->blue_prec)) << image_info->visual->blue_shift));
+      pixel |= gdk_rgb_info_alpha (image_info);
     }
   else if (image_info->visual->type == GDK_VISUAL_STATIC_GRAY ||
 	   image_info->visual->type == GDK_VISUAL_GRAYSCALE)
@@ -2065,6 +2077,7 @@
   gint b_right, b_left;
   gint bpp;
   guint32 pixel;
+  guint32 alpha = gdk_rgb_info_alpha (image_info);
   gint i;
 
   r_right = 8 - image_info->visual->red_prec;
@@ -2088,7 +2101,7 @@
 	  b = bp2[2];
 	  pixel = ((r >> r_right) << r_left) |
 	    ((g >> g_right) << g_left) |
-	    ((b >> b_right) << b_left);
+	    ((b >> b_right) << b_left) | alpha;
 	  for (i = 0; i < bpp; i++)
 	    {
 	      *obptr++ = pixel & 0xff;
@@ -2118,6 +2131,7 @@
   gint b_right, b_left, b_prec;
   gint bpp;
   guint32 pixel;
+  guint32 alpha = gdk_rgb_info_alpha (image_info);
   gint i;
   gint dith;
   gint r1, g1, b1;
@@ -2152,7 +2166,7 @@
 	  b1 = b + (dith >> b_prec);
 	  pixel = (((r1 - (r1 >> r_prec)) >> r_right) << r_left) |
 	    (((g1 - (g1 >> g_prec)) >> g_right) << g_left) |
-	    (((b1 - (b1 >> b_prec)) >> b_right) << b_left);
+	    (((b1 - (b1 >> b_prec)) >> b_right) << b_left) | alpha;
 	  for (i = 0; i < bpp; i++)
 	    {
 	      *obptr++ = pixel & 0xff;
@@ -2182,6 +2196,7 @@
   gint b_right, b_left;
   gint bpp;
   guint32 pixel;
+  guint32 alpha = gdk_rgb_info_alpha (image_info);
   gint shift, shift_init;
 
   r_right = 8 - image_info->visual->red_prec;
@@ -2206,7 +2221,7 @@
 	  b = bp2[2];
 	  pixel = ((r >> r_right) << r_left) |
 	    ((g >> g_right) << g_left) |
-	    ((b >> b_right) << b_left);
+	    ((b >> b_right) << b_left) | alpha;
 	  for (shift = shift_init; shift >= 0; shift -= 8)
 	    {
 	      *obptr++ = (pixel >> shift) & 0xff;
@@ -2235,6 +2250,7 @@
   gint b_right, b_left, b_prec;
   gint bpp;
   guint32 pixel;
+  guint32 alpha = gdk_rgb_info_alpha (image_info);
   gint shift, shift_init;
   gint dith;
   gint r1, g1, b1;
@@ -2270,7 +2286,7 @@
 	  b1 = b + (dith >> b_prec);
 	  pixel = (((r1 - (r1 >> r_prec)) >> r_right) << r_left) |
 	    (((g1 - (g1 >> g_prec)) >> g_right) << g_left) |
-	    (((b1 - (b1 >> b_prec)) >> b_right) << b_left);
+	    (((b1 - (b1 >> b_prec)) >> b_right) << b_left) | alpha;
 	  for (shift = shift_init; shift >= 0; shift -= 8)
 	    {
 	      *obptr++ = (pixel >> shift) & 0xff;
Index: x11/gdkcolor-x11.c
===================================================================
RCS file: /cvs/gnome/gtk+/gdk/x11/gdkcolor-x11.c,v
retrieving revision 1.57
diff -u -r1.57 gdkcolor-x11.c
--- x11/gdkcolor-x11.c	27 May 2004 20:46:58 -0000	1.57
+++ x11/gdkcolor-x11.c	26 Jun 2004 04:21:53 -0000
@@ -1129,8 +1129,8 @@
 	  /* If bits not used for color are used for something other than padding,
 	   * it's likely alpha, so we set them to 1s.
 	   */
-	  guint32 unused = ~ (visual->red_mask | visual->green_mask | visual->blue_mask |
-			      (((~(guint32)0)) << visual->depth));
+	  guint32 beyond = visual->depth >= 32 ? 0 : (((~(guint32)0)) << visual->depth);
+	  guint32 unused = ~ (visual->red_mask | visual->green_mask | visual->blue_mask | beyond);
 	  colors[i].pixel = (unused +
 			     ((colors[i].red >> (16 - visual->red_prec)) << visual->red_shift) +
 			     ((colors[i].green >> (16 - visual->green_prec)) << visual->green_shift) +

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