Never include ancestorLayer transform when testing for overlap.

Source/core/paint/DeprecatedPaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2105 matching lines @@
     if (!enclosingPaginationLayer())
         return physicalBoundingBox(ancestorLayer);
 
     LayoutRect result = flippedLogicalBoundingBox(logicalBoundingBox(), layoutObject());
     convertFromFlowThreadToVisualBoundingBoxInAncestor(this, ancestorLayer, result);
     return result;
 }
 
 LayoutRect DeprecatedPaintLayer::boundingBoxForCompositingOverlapTest() const
 {
-    return overlapBoundsIncludeChildren() ? boundingBoxForCompositing() : fragmentsBoundingBox(this);
+    // Apply NeverIncludeTransformForAncestorLayer, because the geometry map in CompositingInputsUpdater will take care of applying the
+    // transform of |this| (== the ancestorLayer argument to boundingBoxForCompositing).
+    return overlapBoundsIncludeChildren() ? boundingBoxForCompositing(this, NeverIncludeTransformForAncestorLayer) : fragmentsBoundingBox(this);
 }
 
-static void expandRectForReflectionAndStackingChildren(const DeprecatedPaintLayer* ancestorLayer, DeprecatedPaintLayer::CalculateBoundsOptions options, LayoutRect& result)
+static void expandRectForReflectionAndStackingChildren(const DeprecatedPaintLayer* ancestorLayer, LayoutRect& result)
 {
     if (ancestorLayer->reflectionInfo() && !ancestorLayer->reflectionInfo()->reflectionLayer()->hasCompositedDeprecatedPaintLayerMapping())
         result.unite(ancestorLayer->reflectionInfo()->reflectionLayer()->boundingBoxForCompositing(ancestorLayer));
 
     ASSERT(ancestorLayer->stackingNode()->isStackingContext() || !ancestorLayer->stackingNode()->hasPositiveZOrderList());
 
 #if ENABLE(ASSERT)
     LayerListMutationDetector mutationChecker(const_cast<DeprecatedPaintLayer*>(ancestorLayer)->stackingNode());
 #endif
 
     DeprecatedPaintLayerStackingNodeIterator iterator(*ancestorLayer->stackingNode(), AllChildren);
     while (DeprecatedPaintLayerStackingNode* node = iterator.next()) {
         // Here we exclude both directly composited layers and squashing layers
-        // because those Layers don't paint into the graphics layer
+        // because those Layers don't paint into the graphics layer4

[Xianzhu, 2015/08/27 17:15:07]

Nit: typo

[chrishtr, 2015/08/27 17:31:51]

Fixed.

         // for this Layer. For example, the bounds of squashed Layers
         // will be included in the computation of the appropriate squashing
         // GraphicsLayer.
-        if (options != DeprecatedPaintLayer::ApplyBoundsChickenEggHacks && node->layer()->compositingState() != NotComposited)
+        if (node->layer()->compositingState() != NotComposited)
             continue;
-        result.unite(node->layer()->boundingBoxForCompositing(ancestorLayer, options));
+        result.unite(node->layer()->boundingBoxForCompositing(ancestorLayer));
     }
 }
 
 LayoutRect DeprecatedPaintLayer::physicalBoundingBoxIncludingReflectionAndStackingChildren(const DeprecatedPaintLayer* ancestorLayer, const LayoutPoint& offsetFromRoot) const
 {
     LayoutPoint origin;
     LayoutRect result = physicalBoundingBox(ancestorLayer, &origin);
 
     const_cast<DeprecatedPaintLayer*>(this)->stackingNode()->updateLayerListsIfNeeded();
 
-    expandRectForReflectionAndStackingChildren(this, DoNotApplyBoundsChickenEggHacks, result);
+    expandRectForReflectionAndStackingChildren(this, result);
 
     result.moveBy(offsetFromRoot);
     return result;
 }
 
 LayoutRect DeprecatedPaintLayer::boundingBoxForCompositing(const DeprecatedPaintLayer* ancestorLayer, CalculateBoundsOptions options) const
 {
     if (!isSelfPaintingLayer())
         return LayoutRect();
 
@@ skipping 21 matching lines @@
         result = physicalBoundingBox(ancestorLayer, &origin);
 
         const_cast<DeprecatedPaintLayer*>(this)->stackingNode()->updateLayerListsIfNeeded();
 
         // Reflections are implemented with Layers that hang off of the reflected layer. However,
         // the reflection layer subtree does not include the subtree of the parent Layer, so
         // a recursive computation of stacking children yields no results. This breaks cases when there are stacking
         // children of the parent, that need to be included in reflected composited bounds.
         // Fix this by including composited bounds of stacking children of the reflected Layer.
         if (hasCompositedDeprecatedPaintLayerMapping() && parent() && parent()->reflectionInfo() && parent()->reflectionInfo()->reflectionLayer() == this)
-            expandRectForReflectionAndStackingChildren(parent(), options, result);
+            expandRectForReflectionAndStackingChildren(parent(), result);
         else
-            expandRectForReflectionAndStackingChildren(this, options, result);
+            expandRectForReflectionAndStackingChildren(this, result);
 
         // 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
         result.expand(m_layoutObject->style()->filterOutsets());
     }
 
-    if (transform() && (paintsWithTransform(GlobalPaintNormalPhase) || options == ApplyBoundsChickenEggHacks))
+    if (transform() && paintsWithTransform(GlobalPaintNormalPhase) && (this != ancestorLayer || options == MaybeIncludeTransformForAncestorLayer))
         result = transform()->mapRect(result);
 
     if (enclosingPaginationLayer()) {
         convertFromFlowThreadToVisualBoundingBoxInAncestor(this, ancestorLayer, result);
         return result;
     }
     LayoutPoint delta;
     convertToLayerCoords(ancestorLayer, delta);
     result.moveBy(delta);
     return result;
@@ skipping 483 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif