Implement a Hit Test Cache.

Source/core/layout/HitTestResult.cpp

 /*
  * Copyright (C) 2006, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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,
@@ skipping 32 matching lines @@
 #include "core/page/FrameTree.h"
 #include "core/svg/SVGElement.h"
 #include "platform/scroll/Scrollbar.h"
 
 namespace blink {
 
 using namespace HTMLNames;
 
 HitTestResult::HitTestResult()
     : m_hitTestRequest(HitTestRequest::ReadOnly | HitTestRequest::Active)
+    , m_cacheable(true)
     , m_isOverWidget(false)
 {
 }
 
 HitTestResult::HitTestResult(const HitTestRequest& request, const LayoutPoint& point)
     : m_hitTestLocation(point)
     , m_hitTestRequest(request)
+    , m_cacheable(true)
     , m_pointInInnerNodeFrame(point)
     , m_isOverWidget(false)
 {
 }
 
 HitTestResult::HitTestResult(const HitTestRequest& request, const LayoutPoint& centerPoint, unsigned topPadding, unsigned rightPadding, unsigned bottomPadding, unsigned leftPadding)
     : m_hitTestLocation(centerPoint, topPadding, rightPadding, bottomPadding, leftPadding)
     , m_hitTestRequest(request)
+    , m_cacheable(true)
     , m_pointInInnerNodeFrame(centerPoint)
     , m_isOverWidget(false)
 {
 }
 
 HitTestResult::HitTestResult(const HitTestRequest& otherRequest, const HitTestLocation& other)
     : m_hitTestLocation(other)
     , m_hitTestRequest(otherRequest)
+    , m_cacheable(true)
     , m_pointInInnerNodeFrame(m_hitTestLocation.point())
     , m_isOverWidget(false)
 {
 }
 
 HitTestResult::HitTestResult(const HitTestResult& other)
     : m_hitTestLocation(other.m_hitTestLocation)
     , m_hitTestRequest(other.m_hitTestRequest)
     , m_innerNode(other.innerNode())
     , m_innerPossiblyPseudoNode(other.m_innerPossiblyPseudoNode)
     , m_pointInInnerNodeFrame(other.m_pointInInnerNodeFrame)
     , m_localPoint(other.localPoint())
     , m_innerURLElement(other.URLElement())
     , m_scrollbar(other.scrollbar())
     , m_isOverWidget(other.isOverWidget())
 {
     // Only copy the NodeSet in case of list hit test.
     m_listBasedTestResult = adoptPtrWillBeNoop(other.m_listBasedTestResult ? new NodeSet(*other.m_listBasedTestResult) : 0);
 }
 
 HitTestResult::~HitTestResult()
 {
 }
 
 HitTestResult& HitTestResult::operator=(const HitTestResult& other)
 {
     m_hitTestLocation = other.m_hitTestLocation;
     m_hitTestRequest = other.m_hitTestRequest;
+    populateFromCachedResult(other);
+
+    return *this;
+}
+
+bool HitTestResult::equalForCacheability(const HitTestResult& other) const
+{
+    return m_hitTestRequest.equalForCacheability(other.m_hitTestRequest)
+        && m_innerNode == other.innerNode()
+        && m_innerPossiblyPseudoNode == other.innerPossiblyPseudoNode()
+        && m_pointInInnerNodeFrame == other.m_pointInInnerNodeFrame
+        && m_localPoint == other.localPoint()
+        && m_innerURLElement == other.URLElement()
+        && m_scrollbar == other.scrollbar()
+        && m_isOverWidget == other.isOverWidget();
+}
+
+void HitTestResult::cacheValues(const HitTestResult& other)
+{
+    *this = other;
+    m_hitTestRequest = other.m_hitTestRequest.type() & ~HitTestRequest::AvoidCache;
+}
+
+void HitTestResult::populateFromCachedResult(const HitTestResult& other)
+{
     m_innerNode = other.innerNode();
     m_innerPossiblyPseudoNode = other.innerPossiblyPseudoNode();
     m_pointInInnerNodeFrame = other.m_pointInInnerNodeFrame;
     m_localPoint = other.localPoint();
     m_innerURLElement = other.URLElement();
     m_scrollbar = other.scrollbar();
     m_isOverWidget = other.isOverWidget();
+    m_cacheable = other.m_cacheable;
 
     // Only copy the NodeSet in case of list hit test.
     m_listBasedTestResult = adoptPtrWillBeNoop(other.m_listBasedTestResult ? new NodeSet(*other.m_listBasedTestResult) : 0);
-
-    return *this;
 }
 
 DEFINE_TRACE(HitTestResult)
 {
     visitor->trace(m_innerNode);
     visitor->trace(m_innerPossiblyPseudoNode);
     visitor->trace(m_innerURLElement);
     visitor->trace(m_scrollbar);
 #if ENABLE(OILPAN)
     visitor->trace(m_listBasedTestResult);
@@ skipping 385 matching lines @@
     else if (isHTMLMapElement(m_innerNode))
         imageMapImageElement = toHTMLMapElement(m_innerNode)->imageElement();
 
     if (!imageMapImageElement)
         return m_innerNode.get();
 
     return imageMapImageElement;
 }
 
 } // namespace blink