Rename isTreatedAsOrStackingContext to isStacked

third_party/WebKit/Source/core/paint/PaintLayerStackingNode.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 43 matching lines @@
 // FIXME: This should not require PaintLayer. There is currently a cycle where
 // in order to determine if we shoulBeTreatedAsStackingContext() we have to ask the paint
 // layer about some of its state.
 PaintLayerStackingNode::PaintLayerStackingNode(PaintLayer* layer)
     : m_layer(layer)
 #if ENABLE(ASSERT)
     , m_layerListMutationAllowed(true)
     , m_stackingParent(0)
 #endif
 {
-    m_isTreatedAsOrStackingContext = shouldBeTreatedAsOrStackingContext();
+    m_isStacked = shouldStackObject(*layoutObject());

[chrishtr, 2016/03/16 16:26:16]

Why is this code caching shouldStackObject(*layoutObject())? Can't it be easily
recomputed?

[Xianzhu, 2016/03/16 18:10:24]

According to the comment for
PaintLayerStackingNode::isTreatedAsOrStackingContext() (now isStacked), we need
to save the current value and in future updateIsStacked() we need to do
something when it changes.

[chrishtr, 2016/03/16 18:15:09]

Ok then I suggest renaming updateIsStacked to styleChanged(), and renaming
isStacked() to shouldStackObject (or shouldStackObjectInParentStackingContext,
but that seems long). shouldStackObject should take no arguments.

[Xianzhu, 2016/03/16 21:28:41]

The static shouldStackObject was also for another call from
LayoutBoxModelObject::createLayer() which previously called
ComputedStyle::isTreatedAsOrStackingContext().

The new patch set adds back ComputedStyle::isStacked() so that
LayoutBoxModelObject::createLayer() can call it. I think though isStacked() is a
painting concept, it's convenient to let ComputedStyle provide such a method.

The new patch set also combines
PaintLayerStackingNode::updateStackingNodesAfterStyleChange() and
PaintLayerStackingNode::updateIsStacked() into
PaintLayerStackingNode::styleDidChange().

Should we choose isStacked() instead of shouldStackObject()? I think the
"stacked" is clearly defined in the comments and markdown.

 
     // Non-stacking contexts should have empty z-order lists. As this is already the case,
     // there is no need to dirty / recompute these lists.
     m_zOrderListsDirty = isStackingContext();
 }
 
 PaintLayerStackingNode::~PaintLayerStackingNode()
 {
 #if ENABLE(ASSERT)
     if (!layoutObject()->documentBeingDestroyed()) {
@@ skipping 79 matching lines @@
 #endif
 
     m_zOrderListsDirty = false;
 }
 
 void PaintLayerStackingNode::collectLayers(OwnPtr<Vector<PaintLayerStackingNode*>>& posBuffer, OwnPtr<Vector<PaintLayerStackingNode*>>& negBuffer)
 {
     if (layer()->isInTopLayer())
         return;
 
-    if (isTreatedAsOrStackingContext()) {
+    if (isStacked()) {
         OwnPtr<Vector<PaintLayerStackingNode*>>& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
         if (!buffer)
             buffer = adoptPtr(new Vector<PaintLayerStackingNode*>);
         buffer->append(this);
     }
 
     if (!isStackingContext()) {
         for (PaintLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
             if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
                 child->stackingNode()->collectLayers(posBuffer, negBuffer);
@@ skipping 52 matching lines @@
         return;
 
     dirtyStackingContextZOrderLists();
 
     if (isStackingContext)
         dirtyZOrderLists();
     else
         clearZOrderLists();
 }
 
-void PaintLayerStackingNode::updateIsTreatedAsStackingContext()
+void PaintLayerStackingNode::updateIsStacked()
 {
-    bool isTreatedAsOrStackingContext = shouldBeTreatedAsOrStackingContext();
-    if (isTreatedAsOrStackingContext == this->isTreatedAsOrStackingContext())
+    bool isStackedContent = shouldStackObject(*layoutObject());
+    if (isStackedContent == m_isStacked)
         return;
 
-    m_isTreatedAsOrStackingContext = isTreatedAsOrStackingContext;
+    m_isStacked = isStackedContent;
     if (!layoutObject()->documentBeingDestroyed() && !layer()->isRootLayer())
         compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
     dirtyStackingContextZOrderLists();
 }
 
 PaintLayerStackingNode* PaintLayerStackingNode::ancestorStackingContextNode() const
 {
     for (PaintLayer* ancestor = layer()->parent(); ancestor; ancestor = ancestor->parent()) {
         PaintLayerStackingNode* stackingNode = ancestor->stackingNode();
         if (stackingNode->isStackingContext())
             return stackingNode;
     }
     return 0;
 }
 
 LayoutBoxModelObject* PaintLayerStackingNode::layoutObject() const
 {
     return m_layer->layoutObject();
 }
 
 } // namespace blink