Fix border radius on composited children.

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index ebe400f573dabc4f76ab52aa00f487e94387c851..12acd3959c5627dd2aef16b6b0a8f37ed5cfb949 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -200,7 +200,7 @@ CompositedLayerMapping::~CompositedLayerMapping() {
     }
   }
 
-  updateClippingLayers(false, false);
+  updateClippingLayers(false, false, false);
   updateOverflowControlsLayers(false, false, false, false);
   updateChildTransformLayer(false);
   updateForegroundLayer(false);
@@ -244,6 +244,7 @@ void CompositedLayerMapping::destroyGraphicsLayers() {
     m_graphicsLayer->removeFromParent();
 
   m_ancestorClippingLayer = nullptr;
+  m_ancestorClippingMaskLayer = nullptr;
   m_graphicsLayer = nullptr;
   m_foregroundLayer = nullptr;
   m_backgroundLayer = nullptr;
@@ -454,29 +455,37 @@ void CompositedLayerMapping::updateCompositingReasons() {
       m_owningLayer.getSquashingDisallowedReasons());
 }
 
-bool CompositedLayerMapping::
-    owningLayerClippedByLayerNotAboveCompositedAncestor(
-        const PaintLayer* scrollParent) {
+void CompositedLayerMapping::
+    owningLayerClippedOrMaskedByLayerNotAboveCompositedAncestor(
+        const PaintLayer* scrollParent,
+        bool& owningLayerIsClipped,
+        bool& owningLayerIsMasked) {
+  owningLayerIsClipped = false;
+  owningLayerIsMasked = false;
+
   if (!m_owningLayer.parent())
-    return false;
+    return;
 
   const PaintLayer* compositingAncestor =
       m_owningLayer.enclosingLayerWithCompositedLayerMapping(ExcludeSelf);
   if (!compositingAncestor)
-    return false;
+    return;
 
   const LayoutObject* clippingContainer = m_owningLayer.clippingContainer();
   if (!clippingContainer)
-    return false;
+    return;
 
   if (clippingContainer->enclosingLayer() == scrollParent)
-    return false;
+    return;
 
   if (clippingContainer->enclosingLayer()->hasRootScrollerAsDescendant())
-    return false;
+    return;
 
   if (compositingAncestor->layoutObject()->isDescendantOf(clippingContainer))
-    return false;
+    return;
+
+  if (clippingContainer->enclosingLayer()->hasRootScrollerAsDescendant())
+    return;

[Stephen Chennney, 2016/11/08 21:42:51]

flackr@ told me we need this, and I agree.

 
   // We ignore overflow clip here; we want composited overflow content to
   // behave as if it lives in an unclipped universe so it can prepaint, etc.
@@ -491,7 +500,11 @@ bool CompositedLayerMapping::
   clipRectsContext.setIgnoreOverflowClip();
   IntRect parentClipRect = pixelSnappedIntRect(
       m_owningLayer.clipper().backgroundClipRect(clipRectsContext).rect());
-  return parentClipRect != LayoutRect::infiniteIntRect();
+  owningLayerIsClipped = parentClipRect != LayoutRect::infiniteIntRect();
+
+  DCHECK(clippingContainer->style());
+  owningLayerIsMasked =
+      owningLayerIsClipped && clippingContainer->style()->hasBorderRadius();
 }
 
 const PaintLayer* CompositedLayerMapping::scrollParent() {
@@ -547,10 +560,19 @@ bool CompositedLayerMapping::updateGraphicsLayerConfiguration() {
   // layoutObject hierarchy, but a sibling in the z-order hierarchy. Further,
   // that sibling need not be composited at all. In such scenarios, an ancestor
   // clipping layer is necessary to apply the composited clip for this layer.
-  bool needsAncestorClip =
-      owningLayerClippedByLayerNotAboveCompositedAncestor(scrollParent);
 
-  if (updateClippingLayers(needsAncestorClip, needsDescendantsClippingLayer))
+  // TODO(schenney): Can we apply a border radius clip with this ancestor clip
+  // layer? Why do we need a mask for border radius, rather than modifying the
+  // clip rects applied to the ancestor clip?

[Stephen Chennney, 2016/11/08 21:42:51]

This comment should be removed. I know why we have to do it this way.

+  bool needsAncestorClip = false;
+  bool needsAncestorClippingMask = false;
+  owningLayerClippedOrMaskedByLayerNotAboveCompositedAncestor(
+      scrollParent, needsAncestorClip, needsAncestorClippingMask);
+  fprintf(stderr, "needsAnsectorClip %s, needsAncestorClippingMask %s\n",
+      needsAncestorClip ? "true" : "false",
+      needsAncestorClippingMask ? "true" : "false");
+  if (updateClippingLayers(needsAncestorClip, needsAncestorClippingMask,
+                           needsDescendantsClippingLayer))
     layerConfigChanged = true;
 
   bool scrollingConfigChanged = false;
@@ -1058,6 +1080,14 @@ void CompositedLayerMapping::updateAncestorClippingLayerGeometry(
   m_ancestorClippingLayer->setOffsetFromLayoutObject(
       parentClipRect.location() - snappedOffsetFromCompositedAncestor);
 
+  if (m_ancestorClippingMaskLayer) {
+    m_ancestorClippingMaskLayer->setPosition(
+        m_ancestorClippingLayer
+            ->position());  // TODO(schenney) Don't need this?

[Stephen Chennney, 2016/11/08 21:42:51]

Looks like we do not need this, but more testing is required.

+    m_ancestorClippingMaskLayer->setSize(m_ancestorClippingLayer->size());
+    m_ancestorClippingMaskLayer->setNeedsDisplay();
+  }
+
   // The primary layer is then parented in, and positioned relative to this
   // clipping layer.
   graphicsLayerParentLocation = parentClipRect.location();
@@ -1572,6 +1602,9 @@ void CompositedLayerMapping::updateDrawsContent() {
   if (m_backgroundLayer)
     m_backgroundLayer->setDrawsContent(hasPaintedContent);
 
+  if (m_ancestorClippingMaskLayer)
+    m_ancestorClippingMaskLayer->setDrawsContent(true);
+
   if (m_maskLayer)
     m_maskLayer->setDrawsContent(true);
 
@@ -1589,8 +1622,10 @@ void CompositedLayerMapping::updateChildrenTransform() {
 }
 
 // Return true if the layers changed.
-bool CompositedLayerMapping::updateClippingLayers(bool needsAncestorClip,
-                                                  bool needsDescendantClip) {
+bool CompositedLayerMapping::updateClippingLayers(
+    bool needsAncestorClip,
+    bool needsAncestorClippingMask,
+    bool needsDescendantClip) {
   bool layersChanged = false;
 
   if (needsAncestorClip) {
@@ -1599,9 +1634,26 @@ bool CompositedLayerMapping::updateClippingLayers(bool needsAncestorClip,
           createGraphicsLayer(CompositingReasonLayerForAncestorClip);
       m_ancestorClippingLayer->setMasksToBounds(true);
       m_ancestorClippingLayer->setShouldFlattenTransform(false);
+      if (needsAncestorClippingMask) {
+        m_ancestorClippingMaskLayer =
+            createGraphicsLayer(CompositingReasonLayerForAncestorClippingMask);
+        m_ancestorClippingMaskLayer->setPaintingPhase(
+            GraphicsLayerPaintAncestorClippingMask);
+        m_ancestorClippingLayer->setMaskLayer(
+            m_ancestorClippingMaskLayer.get());
+      } else if (!needsAncestorClippingMask) {
+        if (m_ancestorClippingMaskLayer) {
+          m_ancestorClippingMaskLayer = nullptr;
+          m_ancestorClippingLayer->setMaskLayer(nullptr);
+        }
+      }
       layersChanged = true;
     }
   } else if (m_ancestorClippingLayer) {
+    if (m_ancestorClippingMaskLayer) {
+      m_ancestorClippingMaskLayer->removeFromParent();
+      m_ancestorClippingMaskLayer = nullptr;
+    }
     m_ancestorClippingLayer->removeFromParent();
     m_ancestorClippingLayer = nullptr;
     layersChanged = true;
@@ -2143,7 +2195,11 @@ static void updateClipParentForGraphicsLayer(
 
 void CompositedLayerMapping::updateClipParent(const PaintLayer* scrollParent) {
   const PaintLayer* clipParent = nullptr;
-  if (!owningLayerClippedByLayerNotAboveCompositedAncestor(scrollParent)) {
+  bool haveAncestorClipLayer = false;
+  bool haveAncestorMaskLayer = false;
+  owningLayerClippedOrMaskedByLayerNotAboveCompositedAncestor(
+      scrollParent, haveAncestorClipLayer, haveAncestorMaskLayer);
+  if (!haveAncestorClipLayer) {
     clipParent = m_owningLayer.clipParent();
     if (clipParent)
       clipParent =
@@ -2953,6 +3009,8 @@ void CompositedLayerMapping::paintContents(
     paintLayerFlags |= PaintLayerPaintingCompositingMaskPhase;
   if (graphicsLayerPaintingPhase & GraphicsLayerPaintChildClippingMask)
     paintLayerFlags |= PaintLayerPaintingChildClippingMaskPhase;
+  if (graphicsLayerPaintingPhase & GraphicsLayerPaintAncestorClippingMask)
+    paintLayerFlags |= PaintLayerPaintingAncestorClippingMaskPhase;
   if (graphicsLayerPaintingPhase & GraphicsLayerPaintOverflowContents)
     paintLayerFlags |= PaintLayerPaintingOverflowContents;
   if (graphicsLayerPaintingPhase & GraphicsLayerPaintCompositedScroll)
@@ -2969,7 +3027,9 @@ void CompositedLayerMapping::paintContents(
       graphicsLayer == m_backgroundLayer.get() ||
       graphicsLayer == m_maskLayer.get() ||
       graphicsLayer == m_childClippingMaskLayer.get() ||
-      graphicsLayer == m_scrollingContentsLayer.get()) {
+      graphicsLayer == m_scrollingContentsLayer.get() ||
+      graphicsLayer == m_scrollingContentsLayer.get() ||
+      graphicsLayer == m_ancestorClippingMaskLayer.get()) {
     bool paintRootBackgroundOntoScrollingContentsLayer =
         m_backgroundPaintsOntoScrollingContentsLayer;
     DCHECK(!paintRootBackgroundOntoScrollingContentsLayer ||
@@ -3224,6 +3284,8 @@ String CompositedLayerMapping::debugName(
            ")";
   } else if (graphicsLayer == m_ancestorClippingLayer.get()) {
     name = "Ancestor Clipping Layer";
+  } else if (graphicsLayer == m_ancestorClippingMaskLayer.get()) {
+    name = "Ancestor Clipping Mask Layer";
   } else if (graphicsLayer == m_foregroundLayer.get()) {
     name = m_owningLayer.debugName() + " (foreground) Layer";
   } else if (graphicsLayer == m_backgroundLayer.get()) {