WIP: Prune the prepaint tree walk

third_party/WebKit/Source/core/paint/ObjectPaintProperties.h

 // Copyright 2015 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.
 
 #ifndef ObjectPaintProperties_h
 #define ObjectPaintProperties_h
 
 #include "core/CoreExport.h"
+#include "core/paint/PaintPropertyTreeBuilder.h"
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/EffectPaintPropertyNode.h"
 #include "platform/graphics/paint/PaintChunkProperties.h"
 #include "platform/graphics/paint/PropertyTreeState.h"
 #include "platform/graphics/paint/ScrollPaintPropertyNode.h"
 #include "platform/graphics/paint/TransformPaintPropertyNode.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/RefPtr.h"
@@ skipping 98 matching lines @@
   // because some properties inherit from the containing block chain instead of
   // the painting parent and cannot be derived in O(1) during the paint walk.
   // For example, <div style='opacity: 0.3; position: relative; margin: 11px;'/>
   // would have a paint offset of (11px, 11px) and propertyTreeState.effect()
   // would be an effect node with opacity of 0.3 which was created by the div
   // itself. Note that propertyTreeState.transform() would not be null but would
   // instead point to the transform space setup by div's ancestors.
   const PropertyTreeStateWithOffset* localBorderBoxProperties() const {
     return m_localBorderBoxProperties.get();
   }
-  void setLocalBorderBoxProperties(
+  TreeStructureChange setLocalBorderBoxProperties(
       std::unique_ptr<PropertyTreeStateWithOffset> properties) {
+    DCHECK(properties);
+    bool existingNode = !!m_localBorderBoxProperties;
     m_localBorderBoxProperties = std::move(properties);
+    return existingNode ? StructureNotChanged : StructureChanged;
+  }
+  TreeStructureChange clearLocalBorderBoxProperties() {
+    if (m_localBorderBoxProperties) {
+      m_localBorderBoxProperties = nullptr;
+      return StructureChanged;
+    }
+    return StructureNotChanged;
   }
 
   // This is the complete set of property nodes and paint offset that can be
   // used to paint the contents of this object. It is similar to
   // localBorderBoxProperties but includes properties (e.g., overflow clip,
   // scroll translation) that apply to contents. This is suitable for paint
   // invalidation.
   ObjectPaintProperties::PropertyTreeStateWithOffset contentsProperties() const;
 
-  void clearPaintOffsetTranslation() { m_paintOffsetTranslation = nullptr; }
-  void clearTransform() { m_transform = nullptr; }
-  void clearEffect() { m_effect = nullptr; }
-  void clearCssClip() { m_cssClip = nullptr; }
-  void clearCssClipFixedPosition() { m_cssClipFixedPosition = nullptr; }
-  void clearInnerBorderRadiusClip() { m_innerBorderRadiusClip = nullptr; }
-  void clearOverflowClip() { m_overflowClip = nullptr; }
-  void clearLocalBorderBoxProperties() { m_localBorderBoxProperties = nullptr; }
-  void clearPerspective() { m_perspective = nullptr; }
-  void clearSvgLocalToBorderBoxTransform() {
-    m_svgLocalToBorderBoxTransform = nullptr;
+  TreeStructureChange clearPaintOffsetTranslation() {
+    return clear(m_paintOffsetTranslation);
   }
-  void clearScrollTranslation() { m_scrollTranslation = nullptr; }
-  void clearScrollbarPaintOffset() { m_scrollbarPaintOffset = nullptr; }
-  void clearScroll() { m_scroll = nullptr; }
+  TreeStructureChange clearTransform() { return clear(m_transform); }
+  TreeStructureChange clearEffect() { return clear(m_effect); }
+  TreeStructureChange clearCssClip() { return clear(m_cssClip); }
+  TreeStructureChange clearCssClipFixedPosition() {
+    return clear(m_cssClipFixedPosition);
+  }
+  TreeStructureChange clearInnerBorderRadiusClip() {
+    return clear(m_innerBorderRadiusClip);
+  }
+  TreeStructureChange clearOverflowClip() { return clear(m_overflowClip); }
+  TreeStructureChange clearPerspective() { return clear(m_perspective); }
+  TreeStructureChange clearSvgLocalToBorderBoxTransform() {
+    return clear(m_svgLocalToBorderBoxTransform);
+  }
+  TreeStructureChange clearScrollTranslation() {
+    return clear(m_scrollTranslation);
+  }
+  TreeStructureChange clearScrollbarPaintOffset() {
+    return clear(m_scrollbarPaintOffset);
+  }
+  TreeStructureChange clearScroll() { return clear(m_scroll); }
 
   template <typename... Args>
-  void updatePaintOffsetTranslation(Args&&... args) {
-    updateProperty(m_paintOffsetTranslation, std::forward<Args>(args)...);
+  TreeStructureChange updatePaintOffsetTranslation(Args&&... args) {
+    return update(m_paintOffsetTranslation, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateTransform(Args&&... args) {
-    updateProperty(m_transform, std::forward<Args>(args)...);
+  TreeStructureChange updateTransform(Args&&... args) {
+    return update(m_transform, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updatePerspective(Args&&... args) {
-    updateProperty(m_perspective, std::forward<Args>(args)...);
+  TreeStructureChange updatePerspective(Args&&... args) {
+    return update(m_perspective, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateSvgLocalToBorderBoxTransform(Args&&... args) {
+  TreeStructureChange updateSvgLocalToBorderBoxTransform(Args&&... args) {
     DCHECK(!scrollTranslation()) << "SVG elements cannot scroll so there "
                                     "should never be both a scroll translation "
                                     "and an SVG local to border box transform.";
-    updateProperty(m_svgLocalToBorderBoxTransform, std::forward<Args>(args)...);
+    return update(m_svgLocalToBorderBoxTransform, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateScrollTranslation(Args&&... args) {
+  TreeStructureChange updateScrollTranslation(Args&&... args) {
     DCHECK(!svgLocalToBorderBoxTransform())
         << "SVG elements cannot scroll so there should never be both a scroll "
            "translation and an SVG local to border box transform.";
-    updateProperty(m_scrollTranslation, std::forward<Args>(args)...);
+    return update(m_scrollTranslation, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateScrollbarPaintOffset(Args&&... args) {
-    updateProperty(m_scrollbarPaintOffset, std::forward<Args>(args)...);
+  TreeStructureChange updateScrollbarPaintOffset(Args&&... args) {
+    return update(m_scrollbarPaintOffset, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateScroll(Args&&... args) {
-    updateProperty(m_scroll, std::forward<Args>(args)...);
+  TreeStructureChange updateScroll(Args&&... args) {
+    return update(m_scroll, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateEffect(Args&&... args) {
-    updateProperty(m_effect, std::forward<Args>(args)...);
+  TreeStructureChange updateEffect(Args&&... args) {
+    return update(m_effect, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateCssClip(Args&&... args) {
-    updateProperty(m_cssClip, std::forward<Args>(args)...);
+  TreeStructureChange updateCssClip(Args&&... args) {
+    return update(m_cssClip, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateCssClipFixedPosition(Args&&... args) {
-    updateProperty(m_cssClipFixedPosition, std::forward<Args>(args)...);
+  TreeStructureChange updateCssClipFixedPosition(Args&&... args) {
+    return update(m_cssClipFixedPosition, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateInnerBorderRadiusClip(Args&&... args) {
-    updateProperty(m_innerBorderRadiusClip, std::forward<Args>(args)...);
+  TreeStructureChange updateInnerBorderRadiusClip(Args&&... args) {
+    return update(m_innerBorderRadiusClip, std::forward<Args>(args)...);
   }
   template <typename... Args>
-  void updateOverflowClip(Args&&... args) {
-    updateProperty(m_overflowClip, std::forward<Args>(args)...);
+  TreeStructureChange updateOverflowClip(Args&&... args) {
+    return update(m_overflowClip, std::forward<Args>(args)...);
   }
 
 #if DCHECK_IS_ON()
   // Used by FindPropertiesNeedingUpdate.h for recording the current properties.
   std::unique_ptr<ObjectPaintProperties> clone() const {
     std::unique_ptr<ObjectPaintProperties> cloned = create();
     if (m_paintOffsetTranslation)
       cloned->m_paintOffsetTranslation = m_paintOffsetTranslation->clone();
     if (m_transform)
       cloned->m_transform = m_transform->clone();
@@ skipping 28 matching lines @@
                                 state.scroll())));
     }
     return cloned;
   }
 #endif
 
  private:
   ObjectPaintProperties() {}
 
   template <typename PaintPropertyNode, typename... Args>
-  void updateProperty(RefPtr<PaintPropertyNode>& field, Args&&... args) {
-    if (field)
+  TreeStructureChange update(RefPtr<PaintPropertyNode>& field, Args&&... args) {
+    if (field) {
       field->update(std::forward<Args>(args)...);
-    else
-      field = PaintPropertyNode::create(std::forward<Args>(args)...);
+      return StructureNotChanged;
+    }
+    field = PaintPropertyNode::create(std::forward<Args>(args)...);
+    return StructureChanged;
+  }
+
+  template <typename PaintPropertyNode>
+  TreeStructureChange clear(RefPtr<PaintPropertyNode>& field) {
+    if (field) {
+      field = nullptr;
+      return StructureChanged;
+    }
+    return StructureNotChanged;
   }
 
   RefPtr<TransformPaintPropertyNode> m_paintOffsetTranslation;
   RefPtr<TransformPaintPropertyNode> m_transform;
   RefPtr<EffectPaintPropertyNode> m_effect;
   RefPtr<ClipPaintPropertyNode> m_cssClip;
   RefPtr<ClipPaintPropertyNode> m_cssClipFixedPosition;
   RefPtr<ClipPaintPropertyNode> m_innerBorderRadiusClip;
   RefPtr<ClipPaintPropertyNode> m_overflowClip;
   RefPtr<TransformPaintPropertyNode> m_perspective;
   // TODO(pdr): Only LayoutSVGRoot needs this and it should be moved there.
   RefPtr<TransformPaintPropertyNode> m_svgLocalToBorderBoxTransform;
   RefPtr<TransformPaintPropertyNode> m_scrollTranslation;
   RefPtr<TransformPaintPropertyNode> m_scrollbarPaintOffset;
   RefPtr<ScrollPaintPropertyNode> m_scroll;
 
   std::unique_ptr<PropertyTreeStateWithOffset> m_localBorderBoxProperties;
 };
 
 }  // namespace blink
 
 #endif  // ObjectPaintProperties_h