Implement a Hit Test Cache.

Source/core/layout/HitTestResult.cpp

Index: Source/core/layout/HitTestResult.cpp
diff --git a/Source/core/layout/HitTestResult.cpp b/Source/core/layout/HitTestResult.cpp
index 691aa80fac24882799319fcb571b455ce7d17792..e7edf0c828ec458bbe621bbd4a53039b082718b5 100644
--- a/Source/core/layout/HitTestResult.cpp
+++ b/Source/core/layout/HitTestResult.cpp
@@ -108,6 +108,7 @@ HitTestResult& HitTestResult::operator=(const HitTestResult& other)
     m_innerURLElement = other.URLElement();
     m_scrollbar = other.scrollbar();
     m_isOverWidget = other.isOverWidget();
+    m_validityRect = other.m_validityRect;
 
     // Only copy the NodeSet in case of list hit test.
     m_listBasedTestResult = adoptPtrWillBeNoop(other.m_listBasedTestResult ? new NodeSet(*other.m_listBasedTestResult) : 0);
@@ -115,9 +116,35 @@ HitTestResult& HitTestResult::operator=(const HitTestResult& other)
     return *this;
 }
 
+bool HitTestResult::equalForCacheability(const HitTestResult& other) const
+{
+    bool res = 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();
+    // && m_listBasedTestResult == other.m_listBasedTestResult;
+
+    if (!res) {
+        WTF_LOG_ERROR("%d %d %d %d %d %d %d %d", m_hitTestRequest.equalForCacheability(other.m_hitTestRequest),
+            m_innerNode == other.m_innerNode,
+            m_innerPossiblyPseudoNode == other.m_innerPossiblyPseudoNode,
+            m_pointInInnerNodeFrame == other.m_pointInInnerNodeFrame,
+            m_localPoint == other.m_localPoint,
+            m_innerURLElement == other.m_innerURLElement,
+            m_scrollbar == other.m_scrollbar,
+            m_isOverWidget == other.m_isOverWidget);
+    }
+    return res;
+}
+
 DEFINE_TRACE(HitTestResult)
 {
     visitor->trace(m_innerNode);
+
     visitor->trace(m_innerPossiblyPseudoNode);
     visitor->trace(m_innerURLElement);
     visitor->trace(m_scrollbar);
@@ -219,6 +246,55 @@ bool HitTestResult::isSelected() const
     return false;
 }
 
+void HitTestResult::setValidityRect(const LayoutRect& rect)
+{
+    ASSERT(!rect.isEmpty());
+    if (!rect.isEmpty())
+        m_validityRect = rect;
+}
+
+void HitTestResult::shrinkValidityRect(const LayoutRect& rect)
+{
+    LayoutRect tempValidityRect = m_validityRect;
+    if (rect.maxY() <= m_hitTestLocation.point().y() && rect.maxY() > tempValidityRect.y()) {
+        tempValidityRect.shiftYEdgeTo(rect.maxY());
+    }
+    if (rect.y() > m_hitTestLocation.point().y() && rect.y() < tempValidityRect.maxY()) {
+        tempValidityRect.shiftMaxYEdgeTo(rect.y());
+    }
+    if (rect.maxX() <= m_hitTestLocation.point().x() && rect.maxX() > tempValidityRect.x()) {
+        tempValidityRect.shiftXEdgeTo(rect.maxX());
+    }
+    if (rect.x() > m_hitTestLocation.point().x() && rect.x() < tempValidityRect.maxX()) {
+        tempValidityRect.shiftMaxXEdgeTo(rect.x());
+    }
+
+    if (!tempValidityRect.contains(m_hitTestLocation.point())) {
+        tempValidityRect.show(false);
+        rect.show(false);
+        WTF_LOG_ERROR("Layout point %lf %lf", m_hitTestLocation.point().x().toDouble(), m_hitTestLocation.point().y().toDouble());
+
+        //    ASSERT(false);
+        return;
+    }
+    m_validityRect = tempValidityRect;
+}
+
+void HitTestResult::intersectValidityRect(const LayoutRect& rect)
+{
+    LayoutRect tempValidityRect = m_validityRect;
+    tempValidityRect.intersect(rect);
+    if (!tempValidityRect.contains(m_hitTestLocation.point())) {
+        tempValidityRect.show(false);
+        m_validityRect.show(false);
+        WTF_LOG_ERROR("Layout point %lf %lf", m_hitTestLocation.point().x().toDouble(), m_hitTestLocation.point().y().toDouble());
+
+        //    ASSERT(false);
+        return;
+    }
+    m_validityRect = tempValidityRect;
+}
+
 String HitTestResult::spellingToolTip(TextDirection& dir) const
 {
     dir = LTR;
@@ -484,7 +560,7 @@ void HitTestResult::resolveRectBasedTest(Node* resolvedInnerNode, const LayoutPo
     // Update the HitTestResult as if the supplied node had been hit in normal point-based hit-test.
     // Note that we don't know the local point after a rect-based hit-test, but we never use
     // it so shouldn't bother with the cost of computing it.
-    resolvedInnerNode->layoutObject()->updateHitTestResult(*this, LayoutPoint());
+    resolvedInnerNode->layoutObject()->updateHitTestResult(*this, LayoutPoint(), m_validityRect);
     ASSERT(!isRectBasedTest());
 }