Implement a Hit Test Cache.

Source/core/paint/DeprecatedPaintLayer.cpp

Index: Source/core/paint/DeprecatedPaintLayer.cpp
diff --git a/Source/core/paint/DeprecatedPaintLayer.cpp b/Source/core/paint/DeprecatedPaintLayer.cpp
index df5e4e0e0d7c89755b6f7f0906f0d214079927ea..3d84c773a84a364792774ee73d57ea6154c28c33 100644
--- a/Source/core/paint/DeprecatedPaintLayer.cpp
+++ b/Source/core/paint/DeprecatedPaintLayer.cpp
@@ -1660,23 +1660,22 @@ static inline LayoutRect frameVisibleRect(LayoutObject* layoutObject)
 
 bool DeprecatedPaintLayer::hitTest(HitTestResult& result)
 {
-    return hitTest(result.hitTestRequest(), result.hitTestLocation(), result);
-}
-
-bool DeprecatedPaintLayer::hitTest(const HitTestRequest& request, const HitTestLocation& hitTestLocation, HitTestResult& result)
-{
     ASSERT(isSelfPaintingLayer() || hasSelfPaintingLayerDescendant());
 
     // LayoutView should make sure to update layout before entering hit testing
     ASSERT(!layoutObject()->frame()->view()->layoutPending());
     ASSERT(!layoutObject()->document().layoutView()->needsLayout());
 
+    const HitTestRequest& request = result.hitTestRequest();
+    const HitTestLocation& hitTestLocation = result.hitTestLocation();
+
     // Start with frameVisibleRect to ensure we include the scrollbars.
     LayoutRect hitTestArea = frameVisibleRect(layoutObject());
     if (request.ignoreClipping())
         hitTestArea.unite(LayoutRect(layoutObject()->view()->documentRect()));
+    result.setValidityRect(hitTestArea);
 
-    DeprecatedPaintLayer* insideLayer = hitTestLayer(this, 0, result, hitTestArea, hitTestLocation, false);
+    DeprecatedPaintLayer* insideLayer = hitTestLayer(this, 0, result, hitTestArea, result.hitTestLocation(), false);
     if (!insideLayer) {
         // We didn't hit any layer. If we are the root layer and the mouse is -- or just was -- down,
         // return ourselves. We do this so mouse events continue getting delivered after a drag has
@@ -1685,7 +1684,7 @@ bool DeprecatedPaintLayer::hitTest(const HitTestRequest& request, const HitTestL
         // At that time, the events of the mouse should be fired.
         LayoutPoint hitPoint = hitTestLocation.point();
         if (!request.isChildFrameHitTest() && ((request.active() || request.release()) || (request.move() && hitTestArea.contains(hitPoint.x(), hitPoint.y()))) && isRootLayer()) {
-            layoutObject()->updateHitTestResult(result, toLayoutView(layoutObject())->flipForWritingMode(hitTestLocation.point()));
+            layoutObject()->updateHitTestResult(result, toLayoutView(layoutObject())->flipForWritingMode(hitTestLocation.point()), LayoutRect(hitTestLocation.point(), LayoutSize(IntSize(1, 1))));
             insideLayer = this;
         }
     }
@@ -1901,7 +1900,7 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestLayer(DeprecatedPaintLayer* r
         collectFragments(layerFragments, rootLayer, hitTestRect, RootRelativeClipRects, IncludeOverlayScrollbarSize);
 
     if (m_scrollableArea && m_scrollableArea->hitTestResizerInFragments(layerFragments, hitTestLocation)) {
-        layoutObject()->updateHitTestResult(result, hitTestLocation.point());
+        layoutObject()->updateHitTestResult(result, hitTestLocation.point(), boundingRect(hitTestLocation.point()));
         return this;
     }
 
@@ -1910,6 +1909,7 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestLayer(DeprecatedPaintLayer* r
     if (isSelfPaintingLayer()) {
         // Hit test with a temporary HitTestResult, because we only want to commit to 'result' if we know we're frontmost.
         HitTestResult tempResult(result.hitTestRequest(), result.hitTestLocation());
+        tempResult.setValidityRect(result.validityRect());
         bool insideFragmentForegroundRect = false;
         if (hitTestContentsForFragments(layerFragments, tempResult, hitTestLocation, HitTestDescendants, insideFragmentForegroundRect)
             && isHitCandidate(this, false, zOffsetForContentsPtr, unflattenedTransformState.get())) {
@@ -1923,6 +1923,8 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestLayer(DeprecatedPaintLayer* r
             candidateLayer = this;
         } else if (insideFragmentForegroundRect && result.hitTestRequest().listBased()) {
             result.append(tempResult);
+        } else {
+            result.setValidityRect(result.validityRect());
         }
     }
 
@@ -1941,6 +1943,7 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestLayer(DeprecatedPaintLayer* r
 
     if (isSelfPaintingLayer()) {
         HitTestResult tempResult(result.hitTestRequest(), result.hitTestLocation());
+        tempResult.setValidityRect(result.validityRect());
         bool insideFragmentBackgroundRect = false;
         if (hitTestContentsForFragments(layerFragments, tempResult, hitTestLocation, HitTestSelf, insideFragmentBackgroundRect)
             && isHitCandidate(this, false, zOffsetForContentsPtr, unflattenedTransformState.get())) {
@@ -1949,9 +1952,11 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestLayer(DeprecatedPaintLayer* r
             else
                 result = tempResult;
             return this;
-        }
-        if (insideFragmentBackgroundRect && result.hitTestRequest().listBased())
+        } else if (insideFragmentBackgroundRect && result.hitTestRequest().listBased()) {
             result.append(tempResult);
+        } else {
+            result.setValidityRect(tempResult.validityRect());
+        }
     }
 
     return 0;
@@ -2095,6 +2100,7 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestChildren(ChildrenIteration ch
         DeprecatedPaintLayer* childLayer = child->layer();
         DeprecatedPaintLayer* hitLayer = 0;
         HitTestResult tempResult(result.hitTestRequest(), result.hitTestLocation());
+        tempResult.setValidityRect(result.validityRect());
         if (childLayer->isPaginated())
             hitLayer = hitTestPaginatedChildLayer(childLayer, rootLayer, tempResult, hitTestRect, hitTestLocation, transformState, zOffsetForDescendants);
         else
@@ -2112,6 +2118,8 @@ DeprecatedPaintLayer* DeprecatedPaintLayer::hitTestChildren(ChildrenIteration ch
                 result = tempResult;
             if (!depthSortDescendants)
                 break;
+        } else if (!hitLayer) {
+            result.setValidityRect(tempResult.validityRect());
         }
     }