WIP: Reset paint invalidation at transform boundaries.

third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp

Index: third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp
diff --git a/third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp b/third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp
index 07b5e361fbee14735bda680b5369120d56f2f039..a3834e60f3232096aa939748be64fe4f9f56bd71 100644
--- a/third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp
+++ b/third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp
@@ -18,8 +18,7 @@ namespace blink {
 
 static bool supportsCachedOffsets(const LayoutObject& object)
 {
-    return !object.hasTransformRelatedProperty()
-        && !object.hasReflection()
+    return !object.hasReflection()
         && !object.hasFilterInducingProperty()
         && !object.isLayoutFlowThread()
         && !object.isLayoutMultiColumnSpannerPlaceholder()
@@ -35,10 +34,14 @@ PaintInvalidationState::PaintInvalidationState(const LayoutView& layoutView, Vec
     , m_cachedOffsetsEnabled(true)
     , m_cachedOffsetsForAbsolutePositionEnabled(true)
     , m_paintInvalidationContainer(&layoutView.containerForPaintInvalidation())
+    , m_realPaintInvalidationContainer(m_paintInvalidationContainer)
     , m_paintInvalidationContainerForStackedContents(m_paintInvalidationContainer)
+    , m_realPaintInvalidationContainerForStackedContents(m_paintInvalidationContainer)
     , m_containerForAbsolutePosition(layoutView)
     , m_pendingDelayedPaintInvalidations(pendingDelayedPaintInvalidations)
     , m_paintingLayer(*layoutView.layer())
+    , m_transformParent(nullptr)
+    , m_parentPaintInvalidationState(nullptr)
 #if ENABLE(ASSERT)
     , m_didUpdateForChildren(false)
 #endif
@@ -48,6 +51,7 @@ PaintInvalidationState::PaintInvalidationState(const LayoutView& layoutView, Vec
 {
     if (!supportsCachedOffsets(layoutView)) {
         m_cachedOffsetsEnabled = false;
+        LOG(ERROR) << "set to false";
         return;
     }
 
@@ -68,11 +72,15 @@ PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& par
     , m_cachedOffsetsEnabled(parentState.m_cachedOffsetsEnabled)
     , m_cachedOffsetsForAbsolutePositionEnabled(parentState.m_cachedOffsetsForAbsolutePositionEnabled)
     , m_paintInvalidationContainer(parentState.m_paintInvalidationContainer)
+    , m_realPaintInvalidationContainer(parentState.m_realPaintInvalidationContainer)
     , m_paintInvalidationContainerForStackedContents(parentState.m_paintInvalidationContainerForStackedContents)
+    , m_realPaintInvalidationContainerForStackedContents(parentState.m_realPaintInvalidationContainerForStackedContents)
     , m_containerForAbsolutePosition(currentObject.canContainAbsolutePositionObjects() ? currentObject : parentState.m_containerForAbsolutePosition)
     , m_svgTransform(parentState.m_svgTransform)
     , m_pendingDelayedPaintInvalidations(parentState.pendingDelayedPaintInvalidationTargets())
     , m_paintingLayer(currentObject.hasLayer() && toLayoutBoxModelObject(currentObject).hasSelfPaintingLayer() ? *toLayoutBoxModelObject(currentObject).layer() : parentState.m_paintingLayer)
+    , m_transformParent(parentState.m_transformParent)
+    , m_parentPaintInvalidationState(nullptr)
 #if ENABLE(ASSERT)
     , m_didUpdateForChildren(false)
 #endif
@@ -80,6 +88,10 @@ PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& par
     , m_canCheckFastPathSlowPathEquality(parentState.m_canCheckFastPathSlowPathEquality)
 #endif
 {
+    if (parentState.m_currentObject.styleRef().hasTransform()) {
+        m_transformParent = &parentState;
+    }
+
     ASSERT(&m_paintingLayer == currentObject.paintingLayer());
 
     if (currentObject == parentState.m_currentObject) {
@@ -94,14 +106,23 @@ PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& par
 
     ASSERT(parentState.m_didUpdateForChildren);
 
-    if (currentObject.isPaintInvalidationContainer()) {
+    if (currentObject.isPaintInvalidationContainer() || (currentObject.isBox() && currentObject.styleRef().hasTransform())) {
         m_paintInvalidationContainer = toLayoutBoxModelObject(&currentObject);
         if (currentObject.styleRef().isStackingContext())
-            m_paintInvalidationContainerForStackedContents = toLayoutBoxModelObject(&currentObject);
+            m_paintInvalidationContainerForStackedContents = m_paintInvalidationContainer;
+
+        if (currentObject.isPaintInvalidationContainer()) {
+            m_realPaintInvalidationContainer = toLayoutBoxModelObject(&currentObject);
+            if (currentObject.styleRef().isStackingContext())
+                m_realPaintInvalidationContainerForStackedContents = toLayoutBoxModelObject(&currentObject);
+        } else {
+            m_parentPaintInvalidationState = &parentState;
+        }
     } else if (currentObject.isLayoutView()) {
         // m_paintInvalidationContainerForStackedContents is only for stacked descendants in its own frame,
         // because it doesn't establish stacking context for stacked contents in sub-frames.
         // Contents stacked in the root stacking context in this frame should use this frame's paintInvalidationContainer.
+        m_realPaintInvalidationContainerForStackedContents = m_realPaintInvalidationContainer;
         m_paintInvalidationContainerForStackedContents = m_paintInvalidationContainer;
     } else if (currentObject.styleRef().isStacked()
         // This is to exclude some objects (e.g. LayoutText) inheriting stacked style from parent but aren't actually stacked.
@@ -110,6 +131,7 @@ PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& par
         // The current object is stacked, so we should use m_paintInvalidationContainerForStackedContents as its
         // paint invalidation container on which the current object is painted.
         m_paintInvalidationContainer = m_paintInvalidationContainerForStackedContents;
+        m_realPaintInvalidationContainer = m_realPaintInvalidationContainerForStackedContents;
         // We are changing paintInvalidationContainer to m_paintInvalidationContainerForStackedContents. Must disable
         // cached offsets because we didn't track paint offset from m_paintInvalidationContainerForStackedContents.
         // TODO(wangxianzhu): There are optimization opportunities:
@@ -198,6 +220,7 @@ void PaintInvalidationState::updateForCurrentObject(const PaintInvalidationState
             m_cachedOffsetsEnabled = false;
             return;
         }
+        // Does this still work correctly??
         // Use slow path to get the offset of the fixed-position, and enable fast path for descendants.
         FloatPoint fixedOffset = m_currentObject.localToAncestorPoint(FloatPoint(), m_paintInvalidationContainer, TraverseDocumentBoundaries);
         m_paintOffset = LayoutSize(fixedOffset.x(), fixedOffset.y());
@@ -287,7 +310,7 @@ void PaintInvalidationState::updateForNormalChildren()
 
     if (m_currentObject.isLayoutView()) {
         if (!m_currentObject.document().settings() || !m_currentObject.document().settings()->rootLayerScrolls()) {
-            if (m_currentObject != m_paintInvalidationContainer) {
+            if (m_currentObject != m_realPaintInvalidationContainer) {
                 m_paintOffset -= toLayoutView(m_currentObject).frameView()->scrollOffset();
                 addClipRectRelativeToPaintOffset(toLayoutView(m_currentObject).viewRect());
             }
@@ -309,7 +332,7 @@ void PaintInvalidationState::updateForNormalChildren()
 
     // Do not clip scroll layer contents because the compositor expects the whole layer
     // to be always invalidated in-time.
-    if (box == m_paintInvalidationContainer && box.scrollsOverflow())
+    if (box == m_realPaintInvalidationContainer && box.scrollsOverflow())
         ASSERT(!m_clipped); // The box establishes paint invalidation container, so no m_clipped inherited.
     else
         addClipRectRelativeToPaintOffset(box.overflowClipRect(LayoutPoint()));
@@ -397,21 +420,32 @@ static void slowMapToVisualRectInAncestorSpace(const LayoutObject& object, const
 
 void PaintInvalidationState::mapLocalRectToPaintInvalidationContainer(LayoutRect& rect) const
 {
-    ASSERT(!m_didUpdateForChildren);
-
     if (m_cachedOffsetsEnabled) {
 #ifdef CHECK_FAST_PATH_SLOW_PATH_EQUALITY
         LayoutRect slowPathRect(rect);
-        slowMapToVisualRectInAncestorSpace(m_currentObject, *m_paintInvalidationContainer, slowPathRect);
+        slowMapToVisualRectInAncestorSpace(m_currentObject, *m_realPaintInvalidationContainer, slowPathRect);
 #endif
         rect.move(m_paintOffset);
         if (m_clipped)
             rect.intersect(m_clipRect);
+
+        if (m_parentPaintInvalidationState) {
+            if (m_currentObject.container()) {
+                RELEASE_ASSERT(m_currentObject.container()->isBoxModelObject());
+                LayoutBoxModelObject* box = toLayoutBoxModelObject(m_currentObject.container());
+                m_currentObject.mapToVisualRectInAncestorSpace(box, rect);
+            }
+
+            m_parentPaintInvalidationState->mapLocalRectToPaintInvalidationContainer(rect);
+        } else if (m_transformParent) {
+            m_transformParent->mapLocalRectToPaintInvalidationContainer(rect);
+        }
+
 #ifdef CHECK_FAST_PATH_SLOW_PATH_EQUALITY
         assertFastPathAndSlowPathRectsEqual(rect, slowPathRect);
 #endif
     } else {
-        slowMapToVisualRectInAncestorSpace(m_currentObject, *m_paintInvalidationContainer, rect);
+        slowMapToVisualRectInAncestorSpace(m_currentObject, *m_realPaintInvalidationContainer, rect);
     }
 }
 
@@ -420,7 +454,7 @@ void PaintInvalidationState::mapLocalRectToPaintInvalidationBacking(LayoutRect&
     mapLocalRectToPaintInvalidationContainer(rect);
 
     if (m_paintInvalidationContainer->layer()->groupedMapping())
-        PaintLayer::mapRectInPaintInvalidationContainerToBacking(*m_paintInvalidationContainer, rect);
+        PaintLayer::mapRectInPaintInvalidationContainerToBacking(*m_realPaintInvalidationContainer, rect);
 }
 
 void PaintInvalidationState::addClipRectRelativeToPaintOffset(const LayoutRect& localClipRect)