Move PreviousBoxGeometries from BoxPaintInvalidator into LayoutBox::m_rareData

third_party/WebKit/Source/core/layout/LayoutBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 47 matching lines @@
   WTF_MAKE_NONCOPYABLE(LayoutBoxRareData);
   USING_FAST_MALLOC(LayoutBoxRareData);
 
  public:
   LayoutBoxRareData()
       : m_spannerPlaceholder(nullptr),
         m_overrideLogicalContentWidth(-1),
         m_overrideLogicalContentHeight(-1),
         m_hasOverrideContainingBlockContentLogicalWidth(false),
         m_hasOverrideContainingBlockContentLogicalHeight(false),
+        m_hasPreviousOtherBoxGeometries(false),
         m_percentHeightContainer(nullptr),
         m_snapContainer(nullptr),
         m_snapAreas(nullptr) {}
 
   // For spanners, the spanner placeholder that lays us out within the multicol
   // container.
   LayoutMultiColumnSpannerPlaceholder* m_spannerPlaceholder;
 
   LayoutUnit m_overrideLogicalContentWidth;
   LayoutUnit m_overrideLogicalContentHeight;
 
-  bool m_hasOverrideContainingBlockContentLogicalWidth;
-  bool m_hasOverrideContainingBlockContentLogicalHeight;
+  bool m_hasOverrideContainingBlockContentLogicalWidth : 1;
+  bool m_hasOverrideContainingBlockContentLogicalHeight : 1;
+  bool m_hasPreviousOtherBoxGeometries : 1;
+
   LayoutUnit m_overrideContainingBlockContentLogicalWidth;
   LayoutUnit m_overrideContainingBlockContentLogicalHeight;
 
   LayoutUnit m_offsetToNextPage;
 
   LayoutUnit m_paginationStrut;
 
   LayoutBlock* m_percentHeightContainer;
   // For snap area, the owning snap container.
   LayoutBox* m_snapContainer;
   // For snap container, the descendant snap areas that contribute snap
   // points.
   std::unique_ptr<SnapAreaSet> m_snapAreas;
 
   SnapAreaSet& ensureSnapAreas() {
     if (!m_snapAreas)
       m_snapAreas = WTF::wrapUnique(new SnapAreaSet);
 
     return *m_snapAreas;
   }
+
+  // Used by BoxPaintInvalidator. Stores the previous content box size and
+  // layout overflow rect after the last paint invalidation.
+  // These are valid if m_hasPreviousOtherBoxGeometries is true.
+  LayoutSize m_previousContentBoxSize;
+  LayoutRect m_previousLayoutOverflowRect;
 };
 
 // LayoutBox implements the full CSS box model.
 //
 // LayoutBoxModelObject only introduces some abstractions for LayoutInline and
 // LayoutBox. The logic for the model is in LayoutBox, e.g. the storage for the
 // rectangle and offset forming the CSS box (m_frameRect) and the getters for
 // the different boxes.
 //
 // LayoutBox is also the uppermost class to support scrollbars, however the
@@ skipping 200 matching lines @@
       setHeight(size);
     else
       setWidth(size);
   }
 
   LayoutPoint location() const { return m_frameRect.location(); }
   LayoutSize locationOffset() const {
     return LayoutSize(m_frameRect.x(), m_frameRect.y());
   }
   LayoutSize size() const { return m_frameRect.size(); }
-  LayoutSize previousSize() const { return m_previousSize; }
   IntSize pixelSnappedSize() const { return m_frameRect.pixelSnappedSize(); }
 
   void setLocation(const LayoutPoint& location) {
     if (location == m_frameRect.location())
       return;
     m_frameRect.setLocation(location);
     locationChanged();
   }
 
   // The ancestor box that this object's location and physicalLocation are
@@ skipping 972 matching lines @@
   bool intersectsVisibleViewport() const;
 
   bool hasNonCompositedScrollbars() const final;
 
   void ensureIsReadyForPaintInvalidation() override;
 
   virtual bool hasControlClip() const { return false; }
 
   class MutableForPainting : public LayoutObject::MutableForPainting {
    public:
-    void setPreviousSize(const LayoutSize& size) {
-      static_cast<LayoutBox&>(m_layoutObject).m_previousSize = size;
+    void savePreviousSize() { layoutBox().m_previousSize = layoutBox().size(); }
+    void savePreviousOtherBoxGeometries() {
+      layoutBox().savePreviousOtherBoxGeometries();
+    }
+    void clearPreviousOtherBoxGeometries() {
+      if (layoutBox().m_rareData)
+        layoutBox().m_rareData->m_hasPreviousOtherBoxGeometries = false;
     }
 
    protected:
     friend class LayoutBox;
     MutableForPainting(const LayoutBox& box)
         : LayoutObject::MutableForPainting(box) {}
+    LayoutBox& layoutBox() { return static_cast<LayoutBox&>(m_layoutObject); }
   };
+
   MutableForPainting getMutableForPainting() const {
     return MutableForPainting(*this);
   }
 
+  LayoutSize previousSize() const { return m_previousSize; }
+  LayoutSize previousContentBoxSize() const {
+    return m_rareData && m_rareData->m_hasPreviousOtherBoxGeometries
+               ? m_rareData->m_previousContentBoxSize
+               : previousSize();
+  }
+  LayoutRect previousLayoutOverflowRect() const {
+    return m_rareData && m_rareData->m_hasPreviousOtherBoxGeometries
+               ? m_rareData->m_previousLayoutOverflowRect
+               : LayoutRect(LayoutPoint(), previousSize());
+  }
+
  protected:
   virtual LayoutRect controlClipRect(const LayoutPoint&) const {
     return LayoutRect();
   }
 
   void willBeDestroyed() override;
 
   void insertedIntoTree() override;
   void willBeRemovedFromTree() override;
 
@@ skipping 192 matching lines @@
       const LayoutObject& container,
       const LayoutBoxModelObject* ancestorToStopAt) const;
 
   LayoutRectOutsets m_marginBoxOutsets;
 
   void addSnapArea(const LayoutBox&);
   void removeSnapArea(const LayoutBox&);
 
   LayoutRect debugRect() const override;
 
+  void savePreviousOtherBoxGeometries();

[mstensho (USE GERRIT), 2017/02/21 20:16:51]

Wouldn't it be better to keep this logic in MutableForPainting (i.e. make
LayoutBox::MutableForPainting::savePreviousOtherBoxGeometries() non-inline and
put the logic there), since all the getters are implemented there?

Alternatively, provide the getters here as well?

Keeping it all in MutableForPainting sounds more reasonable to me, if this is
only going to be used by the paint code. But as long as it's consistent, I'm
fine.

[Xianzhu, 2017/02/21 20:31:35]

The getters are not in MutableForPainting. They are public methods of LayoutBox,
just below MutableForPainting :)

savePreviousOtherBoxGeometries() was private here just for MutableForPainting.
Making MutableForPainting::savePreviousOtherBoxGeometries() non-inline looks
better. Done.

[mstensho (USE GERRIT), 2017/02/21 21:13:09]

Yikes! I really though I had got used to the enforced new hideous coding style
by now, but that's apparently not the case. Sorry about that.
Yeah, this looks better. Thanks.

+
   // The CSS border box rect for this box.
   //
   // The rectangle is in this box's physical coordinates but with a
   // flipped block-flow direction (see the COORDINATE SYSTEMS section
   // in LayoutBoxModelObject). The location is the distance from this
   // object's border edge to the container's border edge (which is not
   // always the parent). Thus it includes any logical top/left along
   // with this box's margins.
   LayoutRect m_frameRect;
 
@@ skipping 104 matching lines @@
          breakValue == EBreakBetween::kLeft ||
          breakValue == EBreakBetween::kPage ||
          breakValue == EBreakBetween::kRecto ||
          breakValue == EBreakBetween::kRight ||
          breakValue == EBreakBetween::kVerso;
 }
 
 }  // namespace blink
 
 #endif  // LayoutBox_h