Implement a Hit Test Cache.

Source/core/layout/LayoutView.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #ifndef LayoutView_h
 #define LayoutView_h
 
 #include "core/CoreExport.h"
 #include "core/dom/Position.h"
 #include "core/frame/FrameView.h"
+#include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutBlockFlow.h"
 #include "core/layout/LayoutState.h"
 #include "core/layout/PaintInvalidationState.h"
 #include "core/layout/PendingSelection.h"
 #include "platform/PODFreeListArena.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollableArea.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 class DeprecatedPaintLayerCompositor;
 class LayoutQuote;
 
 // The root of the layout tree, corresponding to the CSS initial containing block.
 // It's dimensions match that of the logical viewport (which may be different from
 // the visible viewport in fixed-layout mode), and it is always at position (0,0)
 // relative to the document (and so isn't necessarily in view).
 class CORE_EXPORT LayoutView final : public LayoutBlockFlow {
 public:
     explicit LayoutView(Document*);
     virtual ~LayoutView();
     void willBeDestroyed() override;
 
     bool hitTest(HitTestResult&);
-    bool hitTest(const HitTestRequest&, const HitTestLocation&, HitTestResult&);
 
     // Returns the total count of calls to HitTest, for testing.
     unsigned hitTestCount() const { return m_hitTestCount; }
 
+    void clearHitTestCache();
+
     virtual const char* name() const override { return "LayoutView"; }
 
     virtual bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutView || LayoutBlockFlow::isOfType(type); }
 
     virtual DeprecatedPaintLayerType layerTypeRequired() const override { return NormalDeprecatedPaintLayer; }
 
     virtual bool isChildAllowed(LayoutObject*, const ComputedStyle&) const override;
 
     virtual void layout() override;
     virtual void updateLogicalWidth() override;
@@ skipping 47 matching lines @@
     virtual void absoluteRects(Vector<IntRect>&, const LayoutPoint& accumulatedOffset) const override;
     virtual void absoluteQuads(Vector<FloatQuad>&, bool* wasFixed) const override;
 
     virtual LayoutRect viewRect() const override;
 
     bool shouldDoFullPaintInvalidationForNextLayout() const;
     bool doingFullPaintInvalidation() const { return m_frameView->needsFullPaintInvalidation(); }
 
     LayoutState* layoutState() const { return m_layoutState; }
 
-    virtual void updateHitTestResult(HitTestResult&, const LayoutPoint&) override;
+    virtual void updateHitTestResult(HitTestResult&, const LayoutPoint&, const LayoutRect&) override;
 
     LayoutUnit pageLogicalHeight() const { return m_pageLogicalHeight; }
     void setPageLogicalHeight(LayoutUnit height)
     {
         if (m_pageLogicalHeight != height) {
             m_pageLogicalHeight = height;
             m_pageLogicalHeightChanged = true;
         }
     }
     bool pageLogicalHeightChanged() const { return m_pageLogicalHeightChanged; }
@@ skipping 62 matching lines @@
     LayoutUnit m_pageLogicalHeight;
     bool m_pageLogicalHeightChanged;
     LayoutState* m_layoutState;
     OwnPtr<DeprecatedPaintLayerCompositor> m_compositor;
     RefPtr<IntervalArena> m_intervalArena;
 
     LayoutQuote* m_layoutQuoteHead;
     unsigned m_layoutCounterCount;
 
     unsigned m_hitTestCount;
+    unsigned m_hitTestCacheHits;
+    HitTestResult m_hitTestCacheResult;
+    int m_hitTestCacheLayoutCount;
 
     OwnPtrWillBePersistent<PendingSelection> m_pendingSelection;
 };
 
 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutView, isLayoutView());
 
 // Suspends the LayoutState cached offset and clipRect optimization. Used under transforms
 // that cannot be represented by LayoutState (common in SVG) and when manipulating the layout
 // tree during layout in ways that can trigger paint invalidation of a non-child (e.g. when a list item
 // moves its list marker around). Note that even when disabled, LayoutState is still used to
@@ skipping 15 matching lines @@
             m_paintInvalidationState->m_cachedOffsetsEnabled = true;
     }
 private:
     const PaintInvalidationState* m_paintInvalidationState;
     bool m_didDisable;
 };
 
 } // namespace blink
 
 #endif // LayoutView_h