Improve performance of GeometryMapper cache.

third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/paint/PropertyTreeState.h"
 
 namespace blink {
 
+// All clip caches invalidate themselves by tracking a local cache generation,
+// and invalidating their cache if their cache generation disagrees with
+// s_clipCacheGeneration.
+static unsigned s_clipCacheGeneration = 0;
+
+ClipPaintPropertyNode::ClipPaintPropertyNode(
+    PassRefPtr<const ClipPaintPropertyNode> parent,
+    PassRefPtr<const TransformPaintPropertyNode> localTransformSpace,
+    const FloatRoundedRect& clipRect,
+    CompositingReasons directCompositingReasons)
+    : m_parent(parent),
+      m_localTransformSpace(localTransformSpace),
+      m_clipRect(clipRect),
+      m_directCompositingReasons(directCompositingReasons),
+      m_cacheGeneration(s_clipCacheGeneration) {}
+
 ClipPaintPropertyNode* ClipPaintPropertyNode::root() {
   DEFINE_STATIC_REF(ClipPaintPropertyNode, root,
                     (ClipPaintPropertyNode::create(
                         nullptr, TransformPaintPropertyNode::root(),
                         FloatRoundedRect(LayoutRect::infiniteIntRect()))));
   return root;
 }
 
 String ClipPaintPropertyNode::toString() const {
   return String::format(
       "parent=%p localTransformSpace=%p rect=%s directCompositingReasons=%s",
       m_parent.get(), m_localTransformSpace.get(),
       m_clipRect.toString().ascii().data(),
       compositingReasonsAsString(m_directCompositingReasons).ascii().data());
 }
 
 #if DCHECK_IS_ON()
 
 String ClipPaintPropertyNode::toTreeString() const {
   return blink::PropertyTreeStatePrinter<blink::ClipPaintPropertyNode>()
       .pathAsString(this);
 }
 
 #endif
 
+void ClipPaintPropertyNode::clearCache() {
+  s_clipCacheGeneration++;
+}
+
+Vector<ClipPaintPropertyNode::ClipCacheEntry>*
+ClipPaintPropertyNode::getClipCacheEntries() {
+  if (m_cacheGeneration != s_clipCacheGeneration || !m_clipCache) {
+    m_clipCache.reset(new Vector<ClipCacheEntry>);
+    m_cacheGeneration = s_clipCacheGeneration;
+  }
+
+  return m_clipCache.get();
+}
+
+const FloatClipRect* ClipPaintPropertyNode::getCachedClip(
+    const ClipAndTransform& clipAndTransform) const {
+  auto* clipCacheEntries =
+      const_cast<ClipPaintPropertyNode*>(this)->getClipCacheEntries();
+  for (const auto& entry : *clipCacheEntries) {
+    if (entry.clipAndTransform == clipAndTransform) {
+      return &entry.clipRect;
+    }
+  }
+  return nullptr;
+}
+
+void ClipPaintPropertyNode::setCachedClip(
+    const ClipAndTransform& clipAndTransform,
+    const FloatClipRect& clip) const {
+  auto* clipCacheEntries =
+      const_cast<ClipPaintPropertyNode*>(this)->getClipCacheEntries();
+#if DCHECK_IS_ON
+  for (const auto& entry : clipCachEntries) {
+    if (entry.clipAndTransform == clipAndTransform)
+      DCHECK(false);  // There should be no existing entry.
+  }
+#endif
+  clipCacheEntries->push_back(ClipCacheEntry(clipAndTransform, clip));
+}
+
 }  // namespace blink