Switch DPLStackingNode to use LayoutBoxModelObject

Source/core/paint/DeprecatedPaintLayerStackingNode.cpp

Index: Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
diff --git a/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp b/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
index 83f947c472a1c49fb2c74f4950aa5bf393ba1a70..7ed23a94c0f0ebcaddfe5a9a42870bdae498f21d 100644
--- a/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
+++ b/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
@@ -44,6 +44,7 @@
 #include "config.h"
 #include "core/paint/DeprecatedPaintLayerStackingNode.h"
 
+#include "core/dom/Node.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/DeprecatedPaintLayerCompositor.h"
 #include "core/paint/DeprecatedPaintLayer.h"
@@ -54,8 +55,8 @@ namespace blink {
 // FIXME: This should not require DeprecatedPaintLayer. There is currently a cycle where
 // in order to determine if we shoulBeTreatedAsStackingContextForPainting() we have to ask the paint
 // layer about some of its state.
-DeprecatedPaintLayerStackingNode::DeprecatedPaintLayerStackingNode(DeprecatedPaintLayer* layer)
-    : m_layer(layer)
+DeprecatedPaintLayerStackingNode::DeprecatedPaintLayerStackingNode(LayoutBoxModelObject& layoutObject)
+    : m_layoutObject(layoutObject)
     , m_normalFlowListDirty(true)
 #if ENABLE(ASSERT)
     , m_layerListMutationAllowed(true)
@@ -72,7 +73,7 @@ DeprecatedPaintLayerStackingNode::DeprecatedPaintLayerStackingNode(DeprecatedPai
 DeprecatedPaintLayerStackingNode::~DeprecatedPaintLayerStackingNode()
 {
 #if ENABLE(ASSERT)
-    if (!layoutObject()->documentBeingDestroyed()) {
+    if (!layoutObject().documentBeingDestroyed()) {
         ASSERT(!isInStackingParentZOrderLists());
         ASSERT(!isInStackingParentNormalFlowList());
 
@@ -90,8 +91,8 @@ static inline bool compareZIndex(DeprecatedPaintLayerStackingNode* first, Deprec
 
 DeprecatedPaintLayerCompositor* DeprecatedPaintLayerStackingNode::compositor() const
 {
-    ASSERT(layoutObject()->view());
-    return layoutObject()->view()->compositor();
+    ASSERT(layoutObject().view());
+    return layoutObject().view()->compositor();
 }
 
 void DeprecatedPaintLayerStackingNode::dirtyZOrderLists()
@@ -109,7 +110,7 @@ void DeprecatedPaintLayerStackingNode::dirtyZOrderLists()
         m_negZOrderList->clear();
     m_zOrderListsDirty = true;
 
-    if (!layoutObject()->documentBeingDestroyed())
+    if (!layoutObject().documentBeingDestroyed())
         compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
 }
 
@@ -131,18 +132,45 @@ void DeprecatedPaintLayerStackingNode::dirtyNormalFlowList()
         m_normalFlowList->clear();
     m_normalFlowListDirty = true;
 
-    if (!layoutObject()->documentBeingDestroyed())
+    if (!layoutObject().documentBeingDestroyed())
         compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
 }
 
+static bool isInTopLayer(const LayoutObject& layoutObject)
+{
+    const Node* node = layoutObject.node();
+    return node && node->isElementNode() && toElement(node)->isInTopLayer();
+}
+
 void DeprecatedPaintLayerStackingNode::rebuildZOrderLists()
 {
     ASSERT(m_layerListMutationAllowed);
     ASSERT(isDirtyStackingContext());
 
-    for (DeprecatedPaintLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
-        if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
-            child->stackingNode()->collectLayers(m_posZOrderList, m_negZOrderList);
+    for (LayoutObject* descendant = layoutObject().slowFirstChild(); descendant;) {
+        if (isInTopLayer(*descendant)) {
+            // Top layer objects are handled below.
+            descendant = descendant->nextInPreOrderAfterChildren(&layoutObject());
+            continue;
+        }
+
+        // FIXME: Some non-LayoutBoxModeObject can have position != static and thus would be treated like
+        // stacking context. However we can't store them in the lists unless they have a DeprecatedPaintLayer.
+        if (descendant->styleRef().isTreatedAsStackingContextForPainting() && descendant->hasLayer()) {
+            OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& buffer = (descendant->style()->zIndex() >= 0) ? m_posZOrderList : m_negZOrderList;
+            if (!buffer)
+                buffer = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
+            buffer->append(toLayoutBoxModelObject(descendant)->layer()->stackingNode());
+        }
+
+        if (descendant->styleRef().isStackingContext()) {
+            // We found a stacking context, just continue walking the other subtrees.
+            // They will collect their own descendant stacking contexts.
+            descendant = descendant->nextInPreOrderAfterChildren(&layoutObject());
+        } else {
+            // Not stacking context, continue deeper.
+            descendant = descendant->nextInPreOrder(&layoutObject());
+        }
     }
 
     // Sort the two lists.
@@ -152,19 +180,19 @@ void DeprecatedPaintLayerStackingNode::rebuildZOrderLists()
     if (m_negZOrderList)
         std::stable_sort(m_negZOrderList->begin(), m_negZOrderList->end(), compareZIndex);
 
-    // Append layers for top layer elements after normal layer collection, to ensure they are on top regardless of z-indexes.
+    // Append stacking contexts for top layer elements after normal layer collection, to ensure they are on top regardless of z-indexes.
     // The layoutObjects of top layer elements are children of the view, sorted in top layer stacking order.
-    if (layer()->isRootLayer()) {
-        LayoutView* view = layoutObject()->view();
-        for (LayoutObject* child = view->firstChild(); child; child = child->nextSibling()) {
-            Element* childElement = (child->node() && child->node()->isElementNode()) ? toElement(child->node()) : 0;
-            if (childElement && childElement->isInTopLayer()) {
-                DeprecatedPaintLayer* layer = toLayoutBoxModelObject(child)->layer();
-                // Create the buffer if it doesn't exist yet.
-                if (!m_posZOrderList)
-                    m_posZOrderList = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
-                m_posZOrderList->append(layer->stackingNode());
-            }
+    if (layoutObject().isLayoutView()) {
+        LayoutView& view = toLayoutView(layoutObject());
+        for (LayoutObject* child = view.firstChild(); child; child = child->nextSibling()) {
+            if (!isInTopLayer(*child))
+                continue;
+
+            // Create the buffer if it doesn't exist yet.
+            if (!m_posZOrderList)
+                m_posZOrderList = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
+            ASSERT(child->style()->isStackingContext());
+            m_posZOrderList->append(toLayoutBoxModelObject(child)->layer()->stackingNode());
         }
     }
 
@@ -197,26 +225,6 @@ void DeprecatedPaintLayerStackingNode::updateNormalFlowList()
     m_normalFlowListDirty = false;
 }
 
-void DeprecatedPaintLayerStackingNode::collectLayers(OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& posBuffer, OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& negBuffer)
-{
-    if (layer()->isInTopLayer())
-        return;
-
-    if (isTreatedAsStackingContextForPainting()) {
-        OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
-        if (!buffer)
-            buffer = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
-        buffer->append(this);
-    }
-
-    if (!isStackingContext()) {
-        for (DeprecatedPaintLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
-            if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
-                child->stackingNode()->collectLayers(posBuffer, negBuffer);
-        }
-    }
-}
-
 #if ENABLE(ASSERT)
 bool DeprecatedPaintLayerStackingNode::isInStackingParentZOrderLists() const
 {
@@ -314,9 +322,9 @@ DeprecatedPaintLayerStackingNode* DeprecatedPaintLayerStackingNode::ancestorStac
     return 0;
 }
 
-LayoutBoxModelObject* DeprecatedPaintLayerStackingNode::layoutObject() const
+DeprecatedPaintLayer* DeprecatedPaintLayerStackingNode::layer() const
 {
-    return m_layer->layoutObject();
+    return layoutObject().layer();
 }
 
 } // namespace blink