Remove unnecessary checks in PaintLayer::backgroundIsKnownToBeOpaqueInRect

third_party/WebKit/Source/core/paint/PaintLayer.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 2389 matching lines @@
     return m_rareData && m_rareData->compositedLayerMapping && m_rareData->compositedLayerMapping->hasChildClippingMaskLayer();
 }
 
 bool PaintLayer::paintsWithTransform(GlobalPaintFlags globalPaintFlags) const
 {
     return (transform() || layoutObject()->style()->position() == FixedPosition) && ((globalPaintFlags & GlobalPaintFlattenCompositingLayers) || compositingState() != PaintsIntoOwnBacking);
 }
 
 bool PaintLayer::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
 {
-    if (!isSelfPaintingLayer() && !hasSelfPaintingLayerDescendant())
-        return false;
-
     if (paintsWithTransparency(GlobalPaintNormalPhase))
         return false;
 
     // We can't use hasVisibleContent(), because that will be true if our layoutObject is hidden, but some child
     // is visible and that child doesn't cover the entire rect.
     if (layoutObject()->style()->visibility() != EVisibility::Visible)
         return false;
 
     if (paintsWithFilters() && layoutObject()->style()->filter().hasFilterThatAffectsOpacity())
         return false;
 
     // FIXME: Handle simple transforms.
     if (paintsWithTransform(GlobalPaintNormalPhase))
         return false;
 
-    // FIXME: Remove this check.
     // This function should not be called when layer-lists are dirty.
-    // It is somehow getting triggered during style update.
-    if (m_stackingNode->zOrderListsDirty())
-        return false;
+    DCHECK(!m_stackingNode->zOrderListsDirty());
 
     // FIXME: We currently only check the immediate layoutObject,
-    // which will miss many cases.
+    // which will miss many cases where additional layout objects paint
+    // into this layer.
     if (layoutObject()->backgroundIsKnownToBeOpaqueInRect(localRect))
         return true;
 
     // We can't consult child layers if we clip, since they might cover
     // parts of the rect that are clipped out.
     if (layoutObject()->hasClipRelatedProperty())
         return false;
 
+    // TODO(schenney): This could be improved by unioning the opaque regions of all the children.
+    // That would require a refactoring because currently children just check they at least
+    // cover the given rect, but a unioning method would require children to compute and report
+    // their rects.
     return childBackgroundIsKnownToBeOpaqueInRect(localRect);
 }
 
 bool PaintLayer::childBackgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
 {
-    PaintLayerStackingNodeReverseIterator revertseIterator(*m_stackingNode, PositiveZOrderChildren | NormalFlowChildren | NegativeZOrderChildren);
-    while (PaintLayerStackingNode* child = revertseIterator.next()) {
+    PaintLayerStackingNodeReverseIterator reverseIterator(*m_stackingNode, PositiveZOrderChildren | NormalFlowChildren | NegativeZOrderChildren);
+    while (PaintLayerStackingNode* child = reverseIterator.next()) {
         const PaintLayer* childLayer = child->layer();
         // Stop at composited paint boundaries.
         if (childLayer->isPaintInvalidationContainer())
             continue;
 
         if (!childLayer->canUseConvertToLayerCoords())
             continue;
 
         LayoutPoint childOffset;
         LayoutRect childLocalRect(localRect);
@@ skipping 497 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif