From 571e749d60aaef991dcf8cad50d1cfeb4f9fdd12 Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Sun, 29 Aug 2010 11:52:29 +0200
Subject: [PATCH] x11: Set background color bypassing colormaps

Direct and TrueColor visuals don't alloc colors, so they don't need to
fiddle with colormaps. Just copy the code that computes the pixel value
from gdkcolor-x11.c and use it. For other visual types, don't set the
background color and fallback to background = None.
---
 gdk/x11/gdkwindow-x11.c | 67 ++++++++++++++++++++++++++++++++---------
 1 file changed, 52 insertions(+), 15 deletions(-)

diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 0b1f485516..fecaefc53f 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -2612,21 +2612,59 @@ gdk_window_set_transient_for (GdkWindow *window,
 			  GDK_WINDOW_XID (parent));
 }
 
-static void
+static gboolean
 gdk_window_x11_set_back_color (GdkWindow *window,
-                               GdkColor *color)
+                               double     red,
+                               double     green,
+                               double     blue,
+                               double     alpha)
 {
-  GdkColor allocated = *color;
+  GdkVisual *visual = gdk_window_get_visual (window);
 
-  if (!gdk_colormap_alloc_color (gdk_drawable_get_colormap (window),
-                                 &allocated,
-                                 TRUE, TRUE))
-    return;
+  /* I suppose we could handle these, but that'd require fiddling with 
+   * xrender formats... */
+  if (alpha != 1.0)
+    return FALSE;
 
-  XSetWindowBackground (GDK_WINDOW_XDISPLAY (window),
-			GDK_WINDOW_XID (window), allocated.pixel);
+  switch (visual->type)
+    {
+    case GDK_VISUAL_DIRECT_COLOR:
+    case GDK_VISUAL_TRUE_COLOR:
+	{
+	  /* If bits not used for color are used for something other than padding,
+	   * it's likely alpha, so we set them to 1s.
+	   */
+	  guint padding, pixel;
+
+	  /* Shifting by >= width-of-type isn't defined in C */
+	  if (visual->depth >= 32)
+	    padding = 0;
+	  else
+	    padding = ((~(guint32)0)) << visual->depth;
+	  
+	  pixel = ~ (visual->red_mask | visual->green_mask | visual->blue_mask | padding);
+	  
+	  pixel += (((int) (red   * ((1 << visual->red_prec  ) - 1))) << visual->red_shift  ) +
+		   (((int) (green * ((1 << visual->green_prec) - 1))) << visual->green_shift) +
+		   (((int) (blue  * ((1 << visual->blue_prec ) - 1))) << visual->blue_shift );
 
-  gdk_colormap_free_colors (gdk_drawable_get_colormap (window), &allocated, 1);
+          XSetWindowBackground (GDK_WINDOW_XDISPLAY (window),
+                                GDK_WINDOW_XID (window), pixel);
+	}
+      return TRUE;
+
+    /* These require fiddling with the colormap, and as they're essentially unused
+     * we're just gonna skip them for now.
+     */
+    case GDK_VISUAL_PSEUDO_COLOR:
+    case GDK_VISUAL_GRAYSCALE:
+    case GDK_VISUAL_STATIC_GRAY:
+    case GDK_VISUAL_STATIC_COLOR:
+    default:
+      break;
+    }
+
+  return FALSE;
 }
 
 static gboolean
@@ -2641,7 +2679,6 @@ static void
 gdk_window_x11_set_background (GdkWindow      *window,
                                cairo_pattern_t *pattern)
 {
-  GdkColor color = { 0, };
   double r, g, b, a;
   cairo_surface_t *surface;
   cairo_matrix_t matrix;
@@ -2660,9 +2697,8 @@ gdk_window_x11_set_background (GdkWindow      *window,
     {
     case CAIRO_PATTERN_TYPE_SOLID:
       cairo_pattern_get_rgba (pattern, &r, &g, &b, &a);
-      color.red = r * 65535;
-      color.green = g * 65535;
-      color.blue = b * 65535;
+      if (gdk_window_x11_set_back_color (window, r, g, b, a))
+        return;
       break;
     case CAIRO_PATTERN_TYPE_SURFACE:
       cairo_pattern_get_matrix (pattern, &matrix);
@@ -2692,7 +2728,8 @@ gdk_window_x11_set_background (GdkWindow      *window,
       break;
     }
 
-  gdk_window_x11_set_back_color (window, &color);
+  XSetWindowBackgroundPixmap (GDK_WINDOW_XDISPLAY (window),
+                              GDK_WINDOW_XID (window), None);
 }
 
 static void
-- 
2.30.2