Move computation of RenderLayer::isUnclippedDescendant into CompositingPropertyUpdater

Source/core/rendering/compositing/CompositingPropertyUpdater.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/rendering/compositing/CompositingPropertyUpdater.h"
 
+#include "core/rendering/RenderBlock.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/compositing/CompositedLayerMapping.h"
 
 namespace WebCore {
 
 CompositingPropertyUpdater::CompositingPropertyUpdater(RenderLayer* rootRenderLayer)
     : m_geometryMap(UseTransforms)
     , m_rootRenderLayer(rootRenderLayer)
 {
     rootRenderLayer->updateDescendantDependentFlags();
 }
 
 CompositingPropertyUpdater::~CompositingPropertyUpdater()
 {
 }
 
-void CompositingPropertyUpdater::updateAncestorDependentProperties(RenderLayer* layer, UpdateType updateType, RenderLayer* enclosingCompositedLayer)
+void CompositingPropertyUpdater::updateAncestorDependentProperties(RenderLayer* layer, UpdateType updateType, AncestorInfo info)
 {
     if (!layer->childNeedsToUpdateAncestorDependantProperties() && updateType != ForceUpdate)
         return;
 
     m_geometryMap.pushMappingsToAncestor(layer, layer->parent());
 
     if (layer->hasCompositedLayerMapping())
-        enclosingCompositedLayer = layer;
+        info.enclosingCompositedLayer = layer;
 
     if (layer->needsToUpdateAncestorDependentProperties()) {
-        if (enclosingCompositedLayer)
-            enclosingCompositedLayer->compositedLayerMapping()->setNeedsGraphicsLayerUpdate();
+        if (info.enclosingCompositedLayer)
+            info.enclosingCompositedLayer->compositedLayerMapping()->setNeedsGraphicsLayerUpdate();
         updateType = ForceUpdate;
     }
 
     if (updateType == ForceUpdate) {
         RenderLayer::AncestorDependentProperties properties;
 
         if (!layer->isRootLayer()) {
             properties.clippedAbsoluteBoundingBox = enclosingIntRect(m_geometryMap.absoluteRect(layer->boundingBoxForCompositingOverlapTest()));
             // FIXME: Setting the absBounds to 1x1 instead of 0x0 makes very little sense,
             // but removing this code will make JSGameBench sad.
             // See https://codereview.chromium.org/13912020/
             if (properties.clippedAbsoluteBoundingBox.isEmpty())
                 properties.clippedAbsoluteBoundingBox.setSize(IntSize(1, 1));
 
             IntRect clipRect = pixelSnappedIntRect(layer->clipper().backgroundClipRect(ClipRectsContext(m_rootRenderLayer, AbsoluteClipRects)).rect());
             properties.clippedAbsoluteBoundingBox.intersect(clipRect);
 
             const RenderLayer* parent = layer->parent();
             properties.opacityAncestor = parent->isTransparent() ? parent : parent->ancestorDependentProperties().opacityAncestor;
             properties.transformAncestor = parent->hasTransform() ? parent : parent->ancestorDependentProperties().transformAncestor;
             properties.filterAncestor = parent->hasFilter() ? parent : parent->ancestorDependentProperties().filterAncestor;
+
+            if (layer->renderer()->isOutOfFlowPositioned() && info.ancestorScrollingLayer && !layer->subtreeIsInvisible()) {
+                const RenderObject* container = layer->renderer()->containingBlock();
+                const RenderObject* scroller = info.ancestorScrollingLayer->renderer();
+                properties.isUnclippedDescendant = scroller != container && scroller->isDescendantOf(container);
+            }
         }
 
         layer->updateAncestorDependentProperties(properties);
     }
 
+    if (layer->scrollsOverflow())
+        info.ancestorScrollingLayer = layer;
+
     for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
-        updateAncestorDependentProperties(child, updateType, enclosingCompositedLayer);
+        updateAncestorDependentProperties(child, updateType, info);
 
     m_geometryMap.popMappingsToAncestor(layer->parent());
 
     layer->clearChildNeedsToUpdateAncestorDependantProperties();
 }
 
 #if !ASSERT_DISABLED
 
 void CompositingPropertyUpdater::assertNeedsToUpdateAncestorDependantPropertiesBitsCleared(RenderLayer* layer)
 {
     ASSERT(!layer->childNeedsToUpdateAncestorDependantProperties());
     ASSERT(!layer->needsToUpdateAncestorDependentProperties());
 
     for (RenderLayer* child = layer->firstChild(); child; child = child->nextSibling())
         assertNeedsToUpdateAncestorDependantPropertiesBitsCleared(child);
 }
 
 #endif
 
 } // namespace WebCore