[SPInvalidation] Handle pixel-snapping of paint invalidation rects

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

 // 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.
 
 #ifndef PaintInvalidator_h
 #define PaintInvalidator_h
 
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/paint/GeometryMapper.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class FrameView;
 class LayoutBoxModelObject;
 class LayoutObject;
 class PaintLayer;
 struct PaintPropertyTreeBuilderContext;
 
+struct PaintInvalidationRectInBacking {
+  LayoutRect rect;
+  // True if the rect have been expanded to whole pixels or be rotated, skewed,
+  // etc., so covers more pixels than the object covers.
+  bool coversExtraPixels = false;
+};
+
 struct PaintInvalidatorContext {
   PaintInvalidatorContext(
       const PaintPropertyTreeBuilderContext& treeBuilderContext)
       : treeBuilderContext(treeBuilderContext) {}
 
   PaintInvalidatorContext(
       const PaintPropertyTreeBuilderContext& treeBuilderContext,
       const PaintInvalidatorContext& parentContext)
       : treeBuilderContext(treeBuilderContext),
         forcedSubtreeInvalidationFlags(
@@ skipping 31 matching lines @@
   // The current paint invalidation container for stacked contents (stacking
   // contexts or positioned objects).  It is the nearest ancestor composited
   // object which establishes a stacking context.  See
   // Source/core/paint/README.md ### PaintInvalidationState for details on how
   // stacked contents' paint invalidation containers differ.
   const LayoutBoxModelObject* paintInvalidationContainerForStackedContents =
       nullptr;
 
   PaintLayer* paintingLayer = nullptr;
 
-  LayoutRect oldBounds;
-  LayoutRect newBounds;
+  PaintInvalidationRectInBacking oldBounds;
+  PaintInvalidationRectInBacking newBounds;
   LayoutPoint oldLocation;
   LayoutPoint newLocation;
 };
 
 class PaintInvalidator {
  public:
   void invalidatePaintIfNeeded(FrameView&, PaintInvalidatorContext&);
   void invalidatePaintIfNeeded(const LayoutObject&, PaintInvalidatorContext&);
 
   // Process objects needing paint invalidation on the next frame.
   // See the definition of PaintInvalidationDelayedFull for more details.
   void processPendingDelayedPaintInvalidations();
 
  private:
-  LayoutRect mapLocalRectToPaintInvalidationBacking(
+  PaintInvalidationRectInBacking mapLocalRectToPaintInvalidationBacking(
       const LayoutObject&,
       const FloatRect&,
       const PaintInvalidatorContext&);
-  LayoutRect computePaintInvalidationRectInBacking(
+  PaintInvalidationRectInBacking computePaintInvalidationRectInBacking(
       const LayoutObject&,
       const PaintInvalidatorContext&);
   LayoutPoint computeLocationFromPaintInvalidationBacking(
       const LayoutObject&,
       const PaintInvalidatorContext&);
   void updatePaintingLayer(const LayoutObject&, PaintInvalidatorContext&);
   void updateContext(const LayoutObject&, PaintInvalidatorContext&);
 
   Vector<const LayoutObject*> m_pendingDelayedPaintInvalidations;
   GeometryMapper m_geometryMapper;
 };
 
 }  // namespace blink
 
 #endif  // PaintInvalidator_h