[CSS Filters] Do not use clipping rect when calculating the bounds of a layer

https://bugs.webkit.org/show_bug.cgi?id=83960

Reviewed by Simon Fraser.

The local clip rect should not be used when calculating the bounds of a filter area. Otherwise
drop-shadow might not know about the pixels outside the clipping rectangle, even though the actual shadow might
be inside it.

No new tests added in this patch, but this patch fixes two existing tests that fail.
LayoutTests/css3/filters/filter-repaint-shadow-clipped.html
LayoutTests/css3/filters/filter-repaint-shadow-rotated.html

* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::paintLayerContents):
(WebCore::RenderLayer::calculateLayerBounds):
* rendering/RenderLayer.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@114518 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/ChangeLog

+2012-04-18  Alexandru Chiculita  <achicu@adobe.com>
+
+        [CSS Filters] Do not use clipping rect when calculating the bounds of a layer
+        https://bugs.webkit.org/show_bug.cgi?id=83960
+
+        Reviewed by Simon Fraser.
+        
+        The local clip rect should not be used when calculating the bounds of a filter area. Otherwise
+        drop-shadow might not know about the pixels outside the clipping rectangle, even though the actual shadow might
+        be inside it.
+
+        No new tests added in this patch, but this patch fixes two existing tests that fail.
+        LayoutTests/css3/filters/filter-repaint-shadow-clipped.html
+        LayoutTests/css3/filters/filter-repaint-shadow-rotated.html
+
+        * rendering/RenderLayer.cpp:
+        (WebCore::RenderLayer::paintLayerContents):
+        (WebCore::RenderLayer::calculateLayerBounds):
+        * rendering/RenderLayer.h:
+
 2012-04-18  Mark Pilgrim  <pilgrim@chromium.org>
         Followup to "Call incrementStatsCounter directly"

Source/WebCore/rendering/RenderLayer.cpp

@@ -2983,7 +2983,7 @@ void RenderLayer::paintLayerContents(RenderLayer* rootLayer, GraphicsContext* co
         LayoutPoint rootLayerOffset;
         convertToLayerCoords(rootLayer, rootLayerOffset);
         m_filterRepaintRect.move(rootLayerOffset.x(), rootLayerOffset.y());
-        LayoutRect filterPaintDirtyRect = filterPainter.prepareFilterEffect(this, calculateLayerBounds(this, rootLayer, false, false), parentPaintDirtyRect, m_filterRepaintRect);
+        LayoutRect filterPaintDirtyRect = filterPainter.prepareFilterEffect(this, calculateLayerBounds(this, rootLayer, 0), parentPaintDirtyRect, m_filterRepaintRect);
         m_filterRepaintRect = IntRect();
         // Rewire the old context to a memory buffer, so that we can capture the contents of the layer.
         // NOTE: We saved the old context in the "transparencyLayerContext" local variable, to be able to start a transparency layer
@@ -4100,7 +4100,7 @@ IntRect RenderLayer::absoluteBoundingBox() const
     return pixelSnappedIntRect(boundingBox(root()));
 }
 
-IntRect RenderLayer::calculateLayerBounds(const RenderLayer* layer, const RenderLayer* ancestorLayer, bool includeSelfTransform, bool includeLayerFilterOutsets)
+IntRect RenderLayer::calculateLayerBounds(const RenderLayer* layer, const RenderLayer* ancestorLayer, CalculateLayerBoundsFlags flags)
 {
     if (!layer->isSelfPaintingLayer())
         return IntRect();
@@ -4121,12 +4121,14 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* layer, const Render
 
     LayoutRect unionBounds = boundingBoxRect;
 
-    LayoutRect localClipRect = layer->localClipRect();
-    if (localClipRect != PaintInfo::infiniteRect()) {
-        LayoutPoint ancestorRelOffset;
-        layer->convertToLayerCoords(ancestorLayer, ancestorRelOffset);
-        localClipRect.moveBy(ancestorRelOffset);
-        return pixelSnappedIntRect(localClipRect);
+    if (flags & UseLocalClipRectIfPossible) {
+        LayoutRect localClipRect = layer->localClipRect();
+        if (localClipRect != PaintInfo::infiniteRect()) {
+            LayoutPoint ancestorRelOffset;
+            layer->convertToLayerCoords(ancestorLayer, ancestorRelOffset);
+            localClipRect.moveBy(ancestorRelOffset);
+            return pixelSnappedIntRect(localClipRect);
+        }
     }
 
     if (RenderLayer* reflection = layer->reflectionLayer()) {
@@ -4179,7 +4181,7 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* layer, const Render
     // FIXME: We can optimize the size of the composited layers, by not enlarging
     // filtered areas with the outsets if we know that the filter is going to render in hardware.
     // https://bugs.webkit.org/show_bug.cgi?id=81239
-    if (includeLayerFilterOutsets && layer->renderer()->style()->hasFilterOutsets()) {
+    if ((flags & IncludeLayerFilterOutsets) && layer->renderer()->style()->hasFilterOutsets()) {
         int topOutset;
         int rightOutset;
         int bottomOutset;
@@ -4188,11 +4190,9 @@ IntRect RenderLayer::calculateLayerBounds(const RenderLayer* layer, const Render
         unionBounds.move(-leftOutset, -topOutset);
         unionBounds.expand(leftOutset + rightOutset, topOutset + bottomOutset);
     }
-#else
-    UNUSED_PARAM(includeLayerFilterOutsets);
 #endif
 
-    if (includeSelfTransform && layer->paintsWithTransform(PaintBehaviorNormal)) {
+    if ((flags & IncludeSelfTransform) && layer->paintsWithTransform(PaintBehaviorNormal)) {
         TransformationMatrix* affineTrans = layer->transform();
         boundingBoxRect = affineTrans->mapRect(boundingBoxRect);
         unionBounds = affineTrans->mapRect(unionBounds);

Source/WebCore/rendering/RenderLayer.h

@@ -485,7 +485,14 @@ public:
     // Pixel snapped bounding box relative to the root.
     IntRect absoluteBoundingBox() const;
 
-    static IntRect calculateLayerBounds(const RenderLayer*, const RenderLayer* ancestorLayer, bool includeSelfTransform = true, bool includeLayerFilterOutsets = true);
+    enum CalculateLayerBoundsFlag {
+        IncludeSelfTransform = 1 << 0,
+        UseLocalClipRectIfPossible = 1 << 1,
+        IncludeLayerFilterOutsets = 1 << 2,
+        DefaultCalculateLayerBoundsFlags =  IncludeSelfTransform | UseLocalClipRectIfPossible | IncludeLayerFilterOutsets
+    };
+    typedef unsigned CalculateLayerBoundsFlags;
+    static IntRect calculateLayerBounds(const RenderLayer*, const RenderLayer* ancestorLayer, CalculateLayerBoundsFlags = DefaultCalculateLayerBoundsFlags);
     
     void updateHoverActiveState(const HitTestRequest&, HitTestResult&);