Use a 8xN rather than a 1xN strip for a vertical gradient. This is much more tolerant of slow compositing code, and is worth some extra expense computing the gradient. (#4263, found in test case from Richard Stellingwerff)

2 files changed, 17 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 36484cca8..11a081e0c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,13 @@
 2005-08-27  Owen Taylor  <otaylor@redhat.com>
 
+	* src/cairo-pattern.c (_cairo_pattern_acquire_surface_for_gradient): 
+	Use a 8xN rather than a 1xN strip for a vertical gradient. This
+	is much more tolerant of slow compositing code, and is worth some
+	extra expense computing the gradient. (#4263, found in test case
+	from Richard Stellingwerff)
+
+2005-08-27  Owen Taylor  <otaylor@redhat.com>
+
 	reviewed by: cworth
 
 	* src/cairo-traps.c (_cairo_traps_extract_region): Make the 
diff --git a/src/cairo-pattern.c b/src/cairo-pattern.c
index 7b0130f6a..162d6bf49 100644
--- a/src/cairo-pattern.c
+++ b/src/cairo-pattern.c
@@ -1230,8 +1230,15 @@ _cairo_pattern_acquire_surface_for_gradient (cairo_gradient_pattern_t *pattern,
 	    height = 1;
 	    repeat = TRUE;
 	}
-	if (is_vertical) {
-	    width = 1;
+	/* width-1 repeating patterns are quite slow with scan-line based
+	 * compositing code, so we use a wider strip and spend some extra
+	 * expense in computing the gradient. It's possible that for narrow
+	 * gradients we'd be better off using a 2 or 4 pixel strip; the
+	 * wider the gradient, the more it's worth spending extra time
+	 * computing a sample.
+	 */
+	if (is_vertical && width > 8) {
+	    width = 8;
 	    repeat = TRUE;
 	}
     }