Changeset 181710 in webkit

Timestamp:

Mar 18, 2015, 3:17:34 PM (10 years ago)

Author:

Simon Fraser

Message:

Avoid repaints when changing transform on an element with multiple background images
​https://bugs.webkit.org/show_bug.cgi?id=142841

Reviewed by Zalan Bujtas.

Source/WebCore:

Replace the cheap test for changed images in RenderElement::updateFillImages()
with an exhaustive test that walks the entire list of background images,
since any ensuing repaint is way more expensive than a slightly more expensive check here.

Test: fast/repaint/multiple-backgrounds-style-change.html

• rendering/RenderElement.cpp:

(WebCore::RenderElement::updateFillImages):

• rendering/style/FillLayer.cpp:

(WebCore::layerImagesIdentical): See if both images are the same (either none
or both mask images, and same image pointer).
(WebCore::FillLayer::imagesIdentical): Walk the two FillLayer lists, checking the images
on each one. Returns false if we reach the end of one list before the other, or the images
are different.

• rendering/style/FillLayer.h: New static function; static because

it compares two FillLayer lists, and I think that makes more sense than
a member function.

LayoutTests:

Test that changes transform on a composited element with 2 background images,
and tests for no repaints.

• fast/repaint/multiple-backgrounds-style-change-expected.txt: Added.
• fast/repaint/multiple-backgrounds-style-change.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/fast/repaint/multiple-backgrounds-style-change-expected.txt (added)
• LayoutTests/fast/repaint/multiple-backgrounds-style-change.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderElement.cpp (modified) (1 diff)
• Source/WebCore/rendering/style/FillLayer.cpp (modified) (1 diff)
• Source/WebCore/rendering/style/FillLayer.h (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2015-03-18  Simon Fraser  <simon.fraser@apple.com>
+
+        Avoid repaints when changing transform on an element with multiple background images
+        https://bugs.webkit.org/show_bug.cgi?id=142841
+
+        Reviewed by Zalan Bujtas.
+        
+        Test that changes transform on a composited element with 2 background images,
+        and tests for no repaints.
+
+        * fast/repaint/multiple-backgrounds-style-change-expected.txt: Added.
+        * fast/repaint/multiple-backgrounds-style-change.html: Added.
+
 2015-03-18  Marcos Chavarría Teijeiro  <chavarria1991@gmail.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2015-03-18  Simon Fraser  <simon.fraser@apple.com>
+
+        Avoid repaints when changing transform on an element with multiple background images
+        https://bugs.webkit.org/show_bug.cgi?id=142841
+
+        Reviewed by Zalan Bujtas.
+        
+        Replace the cheap test for changed images in RenderElement::updateFillImages()
+        with an exhaustive test that walks the entire list of background images,
+        since any ensuing repaint is way more expensive than a slightly more expensive check here.
+        
+        Test: fast/repaint/multiple-backgrounds-style-change.html
+
+        * rendering/RenderElement.cpp:
+        (WebCore::RenderElement::updateFillImages):
+        * rendering/style/FillLayer.cpp:
+        (WebCore::layerImagesIdentical): See if both images are the same (either none
+        or both mask images, and same image pointer).
+        (WebCore::FillLayer::imagesIdentical): Walk the two FillLayer lists, checking the images
+        on each one. Returns false if we reach the end of one list before the other, or the images
+        are different.
+        * rendering/style/FillLayer.h: New static function; static because
+        it compares two FillLayer lists, and I think that makes more sense than
+        a member function.
+
 2015-03-18  Anders Carlsson  <andersca@apple.com>
 

trunk/Source/WebCore/rendering/RenderElement.cpp

@@ -338 +338 @@
 {
     // Optimize the common case
-    if (oldLayers && !oldLayers->next() && newLayers && !newLayers->next() && oldLayers->image() == newLayers->image() && oldLayers->maskImage() == newLayers->maskImage())
+    if (FillLayer::imagesIdentical(oldLayers, newLayers))
         return;
     

trunk/Source/WebCore/rendering/style/FillLayer.cpp

@@ -393 +393 @@
 }
 
+static inline bool layerImagesIdentical(const FillLayer& layer1, const FillLayer& layer2)
+{
+    // We just care about pointer equivalency.
+    return layer1.hasMaskImage() == layer2.hasMaskImage() && layer1.image() == layer2.image();
+}
+
+bool FillLayer::imagesIdentical(const FillLayer* layer1, const FillLayer* layer2)
+{
+    for (; layer1 && layer2; layer1 = layer1->next(), layer2 = layer2->next()) {
+        if (!layerImagesIdentical(*layer1, *layer2))
+            return false;
+    }
+
+    return !layer1 && !layer2;
+}
+
 } // namespace WebCore

trunk/Source/WebCore/rendering/style/FillLayer.h

@@ -160 +160 @@
     void cullEmptyLayers();
 
+    static bool imagesIdentical(const FillLayer*, const FillLayer*);
+
     static EFillAttachment initialFillAttachment(EFillLayerType) { return ScrollBackgroundAttachment; }
     static EFillBox initialFillClip(EFillLayerType) { return BorderFillBox; }