Index: ChangeLog
===================================================================
RCS file: /mirrors/freedesktop/cairo/libpixman/ChangeLog,v
retrieving revision 1.57
diff -u -p -r1.57 ChangeLog
--- ChangeLog	4 Mar 2005 15:31:49 -0000	1.57
+++ ChangeLog	4 Mar 2005 15:49:26 -0000
@@ -1,5 +1,11 @@
 2005-03-04  Carl Worth  <cworth@cworth.org>
 
+	* src/ictrap.c (pixman_composite_trapezoids): Intersect bounds of
+	trapezoids with the bounds of the destination surface before
+	creating an intermediate surface.
+
+2005-03-04  Carl Worth  <cworth@cworth.org>
+
 	* src/ictrap.c (pixman_composite_trapezoids): Add comment from
 	xserver's mitrap.c.
 
Index: src/ictrap.c
===================================================================
RCS file: /mirrors/freedesktop/cairo/libpixman/src/ictrap.c,v
retrieving revision 1.23
diff -u -p -r1.23 ictrap.c
--- src/ictrap.c	4 Mar 2005 15:31:49 -0000	1.23
+++ src/ictrap.c	4 Mar 2005 15:32:32 -0000
@@ -117,7 +117,8 @@ pixman_composite_trapezoids (pixman_oper
 			     int		      ntraps)
 {
     pixman_image_t	*image = NULL;
-    pixman_box16_t	bounds;
+    pixman_box16_t	traps_bounds, dst_bounds, bounds;
+    pixman_region16_t	*traps_region, *dst_region;
     int16_t		xDst, yDst;
     int16_t		xRel, yRel;
     pixman_format_t	*format;
@@ -142,9 +143,30 @@ pixman_composite_trapezoids (pixman_oper
     if (!format)
 	return;
 
-    pixman_trapezoid_bounds (ntraps, traps, &bounds);
+    pixman_trapezoid_bounds (ntraps, traps, &traps_bounds);
+
+    traps_region = pixman_region_create_simple (&traps_bounds);
+
+    /* XXX: If the image has a clip region set, we should really be
+     * fetching it here instead, but it looks like we don't yet expose
+     * a pixman_image_get_clip_region function. */
+    dst_bounds.x1 = 0;
+    dst_bounds.y1 = 0;
+    dst_bounds.x2 = pixman_image_get_width (dst);
+    dst_bounds.y2 = pixman_image_get_height (dst);
+
+    dst_region = pixman_region_create_simple (&dst_bounds);
+
+    pixman_region_intersect (traps_region, traps_region, dst_region);
+
+    bounds = *(pixman_region_extents (traps_region));
+
+    pixman_region_destroy (traps_region);
+    pixman_region_destroy (dst_region);
+
     if (bounds.y1 >= bounds.y2 || bounds.x1 >= bounds.x2)
 	return;
+
     image = IcCreateAlphaPicture (dst, format,
 				  bounds.x2 - bounds.x1,
 				  bounds.y2 - bounds.y1);