Refactor PaintLayer location and offset calculation especially for floats

third_party/WebKit/Source/core/paint/PaintInvalidator.cpp

 // Copyright 2016 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 "core/paint/PaintInvalidator.h"
 
 #include "core/editing/FrameSelection.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
@@ skipping 180 matching lines @@
 
   return point;
 }
 
 void PaintInvalidator::updatePaintingLayer(const LayoutObject& object,
                                            PaintInvalidatorContext& context) {
   if (object.hasLayer() &&
       toLayoutBoxModelObject(object).hasSelfPaintingLayer()) {
     context.paintingLayer = toLayoutBoxModelObject(object).layer();
   } else if (object.isColumnSpanAll() ||
-             (object.isFloating() && !object.parent()->isLayoutBlock())) {
+             object.isFloatingWithNonContainingBlockParent()) {
     // See LayoutObject::paintingLayer() for the special-cases of floating under
     // inline and multicolumn.
     context.paintingLayer = object.paintingLayer();
   }
 
   if (object.isLayoutBlockFlow() && toLayoutBlockFlow(object).containsFloats())
     context.paintingLayer->setNeedsPaintPhaseFloat();
 
   if (object == context.paintingLayer->layoutObject())
     return;
@@ skipping 65 matching lines @@
     // paintInvalidationContainerForStackedContents is only for stacked
     // descendants in its own frame, because it doesn't establish stacking
     // context for stacked contents in sub-frames.
     // Contents stacked in the root stacking context in this frame should use
     // this frame's paintInvalidationContainer.
     context.paintInvalidationContainerForStackedContents =
         context.paintInvalidationContainer;
     if (!RuntimeEnabledFeatures::rootLayerScrollingEnabled())
       undoFrameViewContentClipAndScroll.emplace(
           *toLayoutView(object).frameView(), context);
-  } else if (object.isFloating() && !object.parent()->isLayoutBlock()) {
-    // See LayoutObject::paintingLayer() for specialty of floating objects.
+  } else if (object.isFloatingWithNonContainingBlockParent()) {
     context.paintInvalidationContainer =
         &object.containerForPaintInvalidation();
   } else if (object.styleRef().isStacked() &&
              // This is to exclude some objects (e.g. LayoutText) inheriting
              // stacked style from parent but aren't actually stacked.
              object.hasLayer() &&
              context.paintInvalidationContainer !=
                  context.paintInvalidationContainerForStackedContents) {
     // The current object is stacked, so we should use
     // m_paintInvalidationContainerForStackedContents as its paint invalidation
@@ skipping 144 matching lines @@
         PaintInvalidatorContext::ForcedSubtreeInvalidationRectUpdate;
 }
 
 void PaintInvalidator::processPendingDelayedPaintInvalidations() {
   for (auto target : m_pendingDelayedPaintInvalidations)
     target->getMutableForPainting().setShouldDoFullPaintInvalidation(
         PaintInvalidationDelayedFull);
 }
 
 }  // namespace blink