Improve performance of GeometryMapper cache.

third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h

Index: third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h b/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
index 05514071738a79c7bf089d3533fdddf7725f2f62..dfa25c6db71ee7a697e5d86a15064531be6e2bbc 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
@@ -156,7 +156,7 @@ class PLATFORM_EXPORT GeometryMapper {
       const TransformPaintPropertyNode* ancestorTransformNode,
       bool& success);
 
-  FloatClipRect localToAncestorClipRectInternal(
+  const FloatClipRect& localToAncestorClipRectInternal(
       const ClipPaintPropertyNode* descendant,
       const ClipPaintPropertyNode* ancestorClip,
       const TransformPaintPropertyNode* ancestorTransform,
@@ -173,45 +173,72 @@ class PLATFORM_EXPORT GeometryMapper {
       const PropertyTreeState& ancestorState,
       bool& success);
 
-  // Maps from a transform node that is a descendant of the implied ancestor
-  // transform node to the combined transform between the descendant's and the
-  // ancestor's coordinate space.
-  // The "implied ancestor" is the key of the m_transformCache object for which
-  // this TransformCache is a value.
-  using TransformCache =
-      HashMap<const TransformPaintPropertyNode*, TransformationMatrix>;
-
-  // Returns the transform cache for the given ancestor transform node.
-  TransformCache& getTransformCache(const TransformPaintPropertyNode* ancestor);
-
-  // Maps from a descendant clip node to its equivalent "clip visual rect" in
-  // the local transform space of the implied ancestor clip node. The clip
-  // visual rect is defined as the intersection of all clips between the
-  // descendant and the ancestor (*not* including the ancestor) in the clip
-  // tree, individually transformed from their localTransformSpace into the
-  // ancestor's localTransformSpace. If one of the clips that contributes to it
-  // has a border radius, the hasRadius() field is set to true.
-  // The "implied ancestor" is the key of the TransformToClip cachefor which
-  // this ClipCache is a value.
-  using ClipCache = HashMap<const ClipPaintPropertyNode*, FloatClipRect>;
-
-  using TransformToClip =
-      HashMap<const TransformPaintPropertyNode*, std::unique_ptr<ClipCache>>;
-
-  // Returns the clip cache for the given transform space relative to the
-  // given ancestor clip node.
-  ClipCache& getClipCache(const ClipPaintPropertyNode* ancestorClip,
-                          const TransformPaintPropertyNode* ancestorTransform);
+  struct ClipAndTransform {
+    const ClipPaintPropertyNode* ancestorClip;
+    const TransformPaintPropertyNode* ancestorTransform;
+    bool operator==(const ClipAndTransform& other) const {
+      return ancestorClip == other.ancestorClip &&
+             ancestorTransform == other.ancestorTransform;
+    }
+    ClipAndTransform(const ClipPaintPropertyNode* ancestorClipArg,
+                     const TransformPaintPropertyNode* ancestorTransformArg)
+        : ancestorClip(ancestorClipArg),
+          ancestorTransform(ancestorTransformArg) {}
+  };
+
+  struct ClipCacheEntry {
+    const ClipAndTransform clipAndTransform;
+    const FloatClipRect clipRect;
+    ClipCacheEntry(const ClipAndTransform& clipAndTransformArg,
+                   const FloatClipRect& clipRectArg)
+        : clipAndTransform(clipAndTransformArg), clipRect(clipRectArg) {}
+  };
+
+  Vector<ClipCacheEntry>* getClipCacheEntries(
+      const ClipPaintPropertyNode* descendantClip);
+
+  const FloatClipRect* getClip(const ClipPaintPropertyNode* descendantClip,
+                               const ClipAndTransform& ancestors);
+
+  void setClip(const ClipPaintPropertyNode* descendantClip,
+               const ClipAndTransform&,
+               const FloatClipRect&);
+
+  struct TransformCacheEntry {
+    const TransformPaintPropertyNode* ancestorNode;
+    TransformationMatrix toAncestor;
+    TransformCacheEntry(const TransformPaintPropertyNode* ancestorNodeArg,
+                        const TransformationMatrix& toAncestorArg)
+        : ancestorNode(ancestorNodeArg), toAncestor(toAncestorArg) {}
+  };
+
+  Vector<TransformCacheEntry>* getTransformCacheEntries(
+      const TransformPaintPropertyNode* descendantTransform);
+
+  const TransformationMatrix* getTransform(
+      const TransformPaintPropertyNode* descendantTransform,
+      const TransformPaintPropertyNode* ancestorTransform);
+
+  void setTransform(const TransformPaintPropertyNode* descendantTransform,
+                    const TransformPaintPropertyNode* ancestorTransform,
+                    const TransformationMatrix& toAncestor);
 
   friend class GeometryMapperTest;
   friend class PaintLayerClipperTest;
 
-  HashMap<const TransformPaintPropertyNode*, std::unique_ptr<TransformCache>>
+  // Maps from a descendant transform node to a list of all ancestor transform
+  // nodes for which there is a cached transform from the descendant.
+  HashMap<const TransformPaintPropertyNode*,
+          std::unique_ptr<Vector<TransformCacheEntry>>>
       m_transformCache;
-  HashMap<const ClipPaintPropertyNode*, std::unique_ptr<TransformToClip>>
+
+  // Maps from a descendant clip node to a list of all <transform, clip>
+  // ancestor pairs for which there is a cached clip rect from the descendant.
+  HashMap<const ClipPaintPropertyNode*, std::unique_ptr<Vector<ClipCacheEntry>>>
       m_clipCache;
 
   const TransformationMatrix m_identity;
+  const FloatClipRect m_infiniteClip;
 
   DISALLOW_COPY_AND_ASSIGN(GeometryMapper);
 };