Restore sanity to RenderLayerStackingNode::shouldBeNormalFlowOnly

Source/core/rendering/RenderLayerStackingNode.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 38 matching lines @@
 #include "core/rendering/compositing/RenderLayerCompositor.h"
 #include "public/platform/Platform.h"
 
 namespace WebCore {
 
 // FIXME: This should not require RenderLayer. There is currently a cycle where
 // in order to determine if we shoulBeNormalFlowOnly() we have to ask the render
 // layer about some of its state.
 RenderLayerStackingNode::RenderLayerStackingNode(RenderLayer* layer)
     : m_layer(layer)
-    , m_descendantsAreContiguousInStackingOrder(false)
-    , m_descendantsAreContiguousInStackingOrderDirty(true)
     , m_normalFlowListDirty(true)
 #if !ASSERT_DISABLED
     , m_layerListMutationAllowed(true)
     , m_stackingParent(0)
 #endif
 {
     m_isNormalFlowOnly = shouldBeNormalFlowOnly();
 
     // Non-stacking contexts should have empty z-order lists. As this is already the case,
     // there is no need to dirty / recompute these lists.
@@ skipping 14 matching lines @@
 }
 
 // Helper for the sorting of layers by z-index.
 static inline bool compareZIndex(RenderLayerStackingNode* first, RenderLayerStackingNode* second)
 {
     return first->zIndex() < second->zIndex();
 }
 
 RenderLayerCompositor* RenderLayerStackingNode::compositor() const
 {
-    if (!renderer()->view())
-        return 0;
+    ASSERT(renderer()->view());
     return renderer()->view()->compositor();
 }
 
 void RenderLayerStackingNode::dirtyZOrderLists()
 {
     ASSERT(m_layerListMutationAllowed);
     ASSERT(isStackingContext());
 
 #if !ASSERT_DISABLED
     updateStackingParentForZOrderLists(0);
 #endif
 
     if (m_posZOrderList)
         m_posZOrderList->clear();
     if (m_negZOrderList)
         m_negZOrderList->clear();
     m_zOrderListsDirty = true;
 
-    m_descendantsAreContiguousInStackingOrderDirty = true;
-
     if (!renderer()->documentBeingDestroyed())
         compositor()->setCompositingLayersNeedRebuild();
 }
 
 void RenderLayerStackingNode::dirtyStackingContextZOrderLists()
 {
-    RenderLayerStackingNode* stackingContextNode = ancestorStackingContextNode();
-    if (stackingContextNode)
-        stackingContextNode->dirtyZOrderLists();
-
-    RenderLayerStackingNode* stackingNode = ancestorStackingNode();
-    if (stackingNode && stackingNode != stackingContextNode)
+    if (RenderLayerStackingNode* stackingNode = ancestorStackingContextNode())
         stackingNode->dirtyZOrderLists();
 }
 
 void RenderLayerStackingNode::dirtyNormalFlowList()
 {
     ASSERT(m_layerListMutationAllowed);
 
 #if !ASSERT_DISABLED
     updateStackingParentForNormalFlowList(0);
 #endif
 
     if (m_normalFlowList)
         m_normalFlowList->clear();
     m_normalFlowListDirty = true;
 
-    if (!renderer()->documentBeingDestroyed()) {
+    if (!renderer()->documentBeingDestroyed())
         compositor()->setCompositingLayersNeedRebuild();
-    }
 }
 
 void RenderLayerStackingNode::rebuildZOrderLists()
 {
     ASSERT(m_layerListMutationAllowed);
     ASSERT(isDirtyStackingContext());
 
     for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
         if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
             child->stackingNode()->collectLayers(m_posZOrderList, m_negZOrderList);
@@ skipping 139 matching lines @@
     reflectionLayer->stackingNode()->updateZOrderLists();
     reflectionLayer->stackingNode()->updateNormalFlowList();
 }
 
 void RenderLayerStackingNode::updateStackingNodesAfterStyleChange(const RenderStyle* oldStyle)
 {
     bool wasStackingContext = oldStyle ? !oldStyle->hasAutoZIndex() : false;
     EVisibility oldVisibility = oldStyle ? oldStyle->visibility() : VISIBLE;
     int oldZIndex = oldStyle ? oldStyle->zIndex() : 0;
 
-    // FIXME: RenderLayer already handles visibility changes through our visiblity dirty bits. This logic could
+    // FIXME: RenderLayer already handles visibility changes through our visibility dirty bits. This logic could
     // likely be folded along with the rest.
     bool isStackingContext = this->isStackingContext();
     if (isStackingContext == wasStackingContext && oldVisibility == renderer()->style()->visibility() && oldZIndex == zIndex())
         return;
 
     dirtyStackingContextZOrderLists();
 
     if (isStackingContext)
         dirtyZOrderLists();
     else
         clearZOrderLists();
 }
 
 bool RenderLayerStackingNode::shouldBeNormalFlowOnly() const
 {
-    const bool couldBeNormalFlow = renderer()->hasOverflowClip()
-        || renderer()->hasReflection()
-        || renderer()->hasMask()
-        || renderer()->isCanvas()
-        || renderer()->isVideo()
-        || renderer()->isEmbeddedObject()
-        || renderer()->isRenderIFrame()
-        || (renderer()->style()->specifiesColumns() && !layer()->isRootLayer());
-    const bool preventsElementFromBeingNormalFlow = renderer()->isPositioned()
-        || renderer()->hasTransform()
-        || renderer()->hasClipPath()
-        || renderer()->hasFilter()
-        || renderer()->hasBlendMode()
-        || layer()->isTransparent();
-
-    return couldBeNormalFlow && !preventsElementFromBeingNormalFlow;
+    return !isStackingContext() && !renderer()->isPositioned();
 }
 
 void RenderLayerStackingNode::updateIsNormalFlowOnly()
 {
     bool isNormalFlowOnly = shouldBeNormalFlowOnly();
     if (isNormalFlowOnly == this->isNormalFlowOnly())
         return;
 
     m_isNormalFlowOnly = isNormalFlowOnly;
     if (RenderLayer* p = layer()->parent())
         p->stackingNode()->dirtyNormalFlowList();
     dirtyStackingContextZOrderLists();
 }
 
 RenderLayerStackingNode* RenderLayerStackingNode::ancestorStackingContextNode() const
 {
-    RenderLayer* ancestor = layer()->parent();
-    while (ancestor && !ancestor->stackingNode()->isStackingContext())
-        ancestor = ancestor->parent();
-    if (ancestor)
-        return ancestor->stackingNode();
+    for (RenderLayer* ancestor = layer()->parent(); ancestor; ancestor = ancestor->parent()) {
+        RenderLayerStackingNode* stackingNode = ancestor->stackingNode();
+        if (stackingNode->isStackingContext())
+            return stackingNode;
+    }
     return 0;
 }
 
-RenderLayerStackingNode* RenderLayerStackingNode::ancestorStackingNode() const
-{
-    RenderLayer* ancestor = layer()->parent();
-    while (ancestor && !ancestor->stackingNode()->isStackingContext())
-        ancestor = ancestor->parent();
-    if (ancestor)
-        return ancestor->stackingNode();
-    return 0;
-}
-
 RenderLayerModelObject* RenderLayerStackingNode::renderer() const
 {
     return m_layer->renderer();
 }
 
 } // namespace WebCore