Improve handling of PaintInvalidationLayer (renamed to PaintInvalidationSubtree)

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 096ca917ca303a9fb32a65c0f77489cfe3cdedf3..8d2b7eadfc82a40a3de95c8afc60ac29c6a463d5 100644
--- a/third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp
+++ b/third_party/WebKit/Source/core/layout/PaintInvalidationState.cpp
@@ -29,8 +29,7 @@ static bool supportsCachedOffsets(const LayoutObject& object)
 
 PaintInvalidationState::PaintInvalidationState(const LayoutView& layoutView, Vector<LayoutObject*>& pendingDelayedPaintInvalidations)
     : m_currentObject(layoutView)
-    , m_forcedSubtreeInvalidationWithinContainer(false)
-    , m_forcedSubtreeInvalidationRectUpdateWithinContainer(false)
+    , m_forcedSubtreeInvalidationFlags(0)
     , m_clipped(false)
     , m_clippedForAbsolutePosition(false)
     , m_cachedOffsetsEnabled(true)
@@ -59,8 +58,7 @@ PaintInvalidationState::PaintInvalidationState(const LayoutView& layoutView, Vec
 
 PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& parentState, const LayoutObject& currentObject)
     : m_currentObject(currentObject)
-    , m_forcedSubtreeInvalidationWithinContainer(parentState.m_forcedSubtreeInvalidationWithinContainer)
-    , m_forcedSubtreeInvalidationRectUpdateWithinContainer(parentState.m_forcedSubtreeInvalidationRectUpdateWithinContainer)
+    , m_forcedSubtreeInvalidationFlags(parentState.m_forcedSubtreeInvalidationFlags)
     , m_clipped(parentState.m_clipped)
     , m_clippedForAbsolutePosition(parentState.m_clippedForAbsolutePosition)
     , m_clipRect(parentState.m_clipRect)
@@ -117,6 +115,8 @@ PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& par
         //   descendants if possible; or
         // - Track offset between the two paintInvalidationContainers.
         m_cachedOffsetsEnabled = false;
+        if (m_forcedSubtreeInvalidationFlags & FullInvalidationForStackedContents)

[chrishtr, 2016/05/09 22:20:42]

Where was this logic previously?

[Xianzhu, 2016/05/10 17:17:12]

It was in traverseNonCompositingDescendants() called from
LayoutObject::setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants().
It's for the following case (the same case in which we are required to track two
paint invalidation containers):

  <paint invalidation container of stacked contents>
    <paint invalidation container of normal contents>
      <stacked content>

This ensures that the stacked contents whose paint invalidaiton container is not
the nearest isPaintInvalidationContainer ancestor in the layout tree are
invalidated.

Links to old code:
(the call site)
https://codereview.chromium.org/1950573003/diff/100001/third_party/WebKit/Sou...

(the traversal)
https://codereview.chromium.org/1950573003/diff/100001/third_party/WebKit/Sou...

+            m_forcedSubtreeInvalidationFlags |= FullInvalidation;
     }
 
     if (!currentObject.isBoxModelObject() && !currentObject.isSVG())
@@ -142,21 +142,25 @@ PaintInvalidationState::PaintInvalidationState(const PaintInvalidationState& par
         // continue forcing a check for paint invalidation, since we're
         // descending into a different invalidation container. (For instance if
         // our parents were moved, the entire container will just move.)
-        m_forcedSubtreeInvalidationWithinContainer = false;
-        m_forcedSubtreeInvalidationRectUpdateWithinContainer = false;
-
-        if (currentObject == m_paintInvalidationContainerForStackedContents
-            && currentObject != m_containerForAbsolutePosition
-            && m_cachedOffsetsForAbsolutePositionEnabled
-            && m_cachedOffsetsEnabled) {
-            // The current object is the new paintInvalidationContainer for absolute-position descendants but is not their container.
-            // Call updateForCurrentObject() before resetting m_paintOffset to get paint offset of the current object
-            // from the original paintInvalidationContainerForStackingContents, then use this paint offset to adjust
-            // m_paintOffsetForAbsolutePosition.
-            updateForCurrentObject(parentState);
-            m_paintOffsetForAbsolutePosition -= m_paintOffset;
-            if (m_clippedForAbsolutePosition)
-                m_clipRectForAbsolutePosition.move(-m_paintOffset);
+        // However, we need to keep the FullInvalidationForStackedContents flag
+        // if the current object isn't the paint invalidation container of
+        // stacked contents.
+        if (currentObject != m_paintInvalidationContainerForStackedContents) {
+            m_forcedSubtreeInvalidationFlags &= FullInvalidationForStackedContents;
+        } else {
+            m_forcedSubtreeInvalidationFlags = 0;
+            if (currentObject != m_containerForAbsolutePosition
+                && m_cachedOffsetsForAbsolutePositionEnabled
+                && m_cachedOffsetsEnabled) {
+                // The current object is the new paintInvalidationContainer for absolute-position descendants but is not their container.
+                // Call updateForCurrentObject() before resetting m_paintOffset to get paint offset of the current object
+                // from the original paintInvalidationContainerForStackingContents, then use this paint offset to adjust
+                // m_paintOffsetForAbsolutePosition.
+                updateForCurrentObject(parentState);
+                m_paintOffsetForAbsolutePosition -= m_paintOffset;
+                if (m_clippedForAbsolutePosition)
+                    m_clipRectForAbsolutePosition.move(-m_paintOffset);
+            }
         }
 
         m_clipped = false; // Will be updated in updateForChildren().
@@ -229,13 +233,27 @@ void PaintInvalidationState::updateForCurrentObject(const PaintInvalidationState
         m_paintOffset += toLayoutBoxModelObject(m_currentObject).layer()->offsetForInFlowPosition();
 }
 
-void PaintInvalidationState::updateForChildren()
+void PaintInvalidationState::updateForChildren(PaintInvalidationReason reason)
 {
 #if ENABLE(ASSERT)
     ASSERT(!m_didUpdateForChildren);
     m_didUpdateForChildren = true;
 #endif
 
+    switch (reason) {
+    case PaintInvalidationDelayedFull:
+        pushDelayedPaintInvalidationTarget(const_cast<LayoutObject&>(m_currentObject));
+        break;
+    case PaintInvalidationSubtree:
+        m_forcedSubtreeInvalidationFlags |= (FullInvalidation | FullInvalidationForStackedContents);
+        break;
+    case PaintInvalidationSVGResourceChange:
+        setForceSubtreeInvalidationCheckingWithinContainer();
+        break;
+    default:
+        break;
+    }
+
     updateForNormalChildren();
 
     if (m_currentObject == m_containerForAbsolutePosition) {