WIP: Construct SPV2's scroll paint property tree

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 "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"
 #include <memory>
 
 namespace blink {
 
 // This class stores property tree related information associated with a LayoutObject.
 // Currently there are two groups of information:
@@ skipping 24 matching lines @@
     //                                      This is equivalent to the local border box space above,
     //                                      with pixel snapped paint offset baked in. It is really redundant,
     //                                      but it is a pain to teach scrollbars to paint with an offset.
     const TransformPaintPropertyNode* paintOffsetTranslation() const { return m_paintOffsetTranslation.get(); }
     const TransformPaintPropertyNode* transform() const { return m_transform.get(); }
     const TransformPaintPropertyNode* perspective() const { return m_perspective.get(); }
     const TransformPaintPropertyNode* svgLocalToBorderBoxTransform() const { return m_svgLocalToBorderBoxTransform.get(); }
     const TransformPaintPropertyNode* scrollTranslation() const { return m_scrollTranslation.get(); }
     const TransformPaintPropertyNode* scrollbarPaintOffset() const { return m_scrollbarPaintOffset.get(); }
 
+    // Auxillary scrolling information for compositor-thread scrolling. Includes information such as the
+    // hierarchy of scrollable areas, the extent that can be scrolled, etc.
+    const ScrollPaintPropertyNode* scroll() const { return m_scroll.get(); }
+
     const EffectPaintPropertyNode* effect() const { return m_effect.get(); }
 
     // The hierarchy of the clip subtree created by a LayoutObject is as follows:
     // [ css clip ]
     // [ css clip fixed position]
     // |
     // +--- [ overflow clip ]
     const ClipPaintPropertyNode* cssClip() const { return m_cssClip.get(); }
     const ClipPaintPropertyNode* cssClipFixedPosition() const { return m_cssClipFixedPosition.get(); }
     const ClipPaintPropertyNode* overflowClip() const { return m_overflowClip.get(); }
 
     // This is a complete set of property nodes that should be used as a starting point to paint
     // this layout object. It is needed becauase some property inherits from the containing block,
     // not painting parent, thus can't be derived in O(1) during paint walk.
     // Note: If this layout object has transform or stacking-context effects, those are already
     // baked into in the context here. However for properties that affects only children,
     // for example, perspective and overflow clip, those should be applied by the painter
     // at the right painting step.
     struct LocalBorderBoxProperties {
         LayoutPoint paintOffset;
+        // TODO(pdr): Rename this GeometryPropertyTreeState because it does not contain scroll.
         PropertyTreeState propertyTreeState;
+        const ScrollPaintPropertyNode* scroll;
     };
     const LocalBorderBoxProperties* localBorderBoxProperties() const { return m_localBorderBoxProperties.get(); }
     // ContentsProperties is the PropertyTreeState state that is the same as in localBorderBoxProperties, except that it is inside
     // any clips and scrolls caused by this object. This PropertyTreeState is suitable as the destination for paint invalidation.
     void getContentsProperties(PropertyTreeState&) 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 clearOverflowClip() { m_overflowClip = nullptr; }
     void clearPerspective() { m_perspective = nullptr; }
     void clearSvgLocalToBorderBoxTransform() { m_svgLocalToBorderBoxTransform = nullptr; }
     void clearScrollTranslation() { m_scrollTranslation = nullptr; }
     void clearScrollbarPaintOffset() { m_scrollbarPaintOffset = nullptr; }
+    void clearScroll() { m_scroll = nullptr; }
 
     template <typename... Args> TransformPaintPropertyNode* createOrUpdatePaintOffsetTranslation(Args&&... args) { return createOrUpdateProperty(m_paintOffsetTranslation, std::forward<Args>(args)...); }
     template <typename... Args> TransformPaintPropertyNode* createOrUpdateTransform(Args&&... args) { return createOrUpdateProperty(m_transform, std::forward<Args>(args)...); }
     template <typename... Args> TransformPaintPropertyNode* createOrUpdatePerspective(Args&&... args) { return createOrUpdateProperty(m_perspective, std::forward<Args>(args)...); }
     template <typename... Args> TransformPaintPropertyNode* createOrUpdateSvgLocalToBorderBoxTransform(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.";
         return createOrUpdateProperty(m_svgLocalToBorderBoxTransform, std::forward<Args>(args)...);
     }
     template <typename... Args> TransformPaintPropertyNode* createOrUpdateScrollTranslation(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.";
         return createOrUpdateProperty(m_scrollTranslation, std::forward<Args>(args)...);
     }
     template <typename... Args> TransformPaintPropertyNode* createOrUpdateScrollbarPaintOffset(Args&&... args) { return createOrUpdateProperty(m_scrollbarPaintOffset, std::forward<Args>(args)...); }
+    template <typename... Args> ScrollPaintPropertyNode* createOrUpdateScroll(Args&&... args) { return createOrUpdateProperty(m_scroll, std::forward<Args>(args)...); }
     template <typename... Args> EffectPaintPropertyNode* createOrUpdateEffect(Args&&... args) { return createOrUpdateProperty(m_effect, std::forward<Args>(args)...); }
     template <typename... Args> ClipPaintPropertyNode* createOrUpdateCssClip(Args&&... args) { return createOrUpdateProperty(m_cssClip, std::forward<Args>(args)...); }
     template <typename... Args> ClipPaintPropertyNode* createOrUpdateCssClipFixedPosition(Args&&... args) { return createOrUpdateProperty(m_cssClipFixedPosition, std::forward<Args>(args)...); }
     template <typename... Args> ClipPaintPropertyNode* createOrUpdateOverflowClip(Args&&... args) { return createOrUpdateProperty(m_overflowClip, std::forward<Args>(args)...); }
 
     void setLocalBorderBoxProperties(std::unique_ptr<LocalBorderBoxProperties> properties) { m_localBorderBoxProperties = std::move(properties); }
 
 private:
     ObjectPaintProperties() { }
 
@@ skipping 11 matching lines @@
     RefPtr<TransformPaintPropertyNode> m_transform;
     RefPtr<EffectPaintPropertyNode> m_effect;
     RefPtr<ClipPaintPropertyNode> m_cssClip;
     RefPtr<ClipPaintPropertyNode> m_cssClipFixedPosition;
     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<LocalBorderBoxProperties> m_localBorderBoxProperties;
 };
 
 } // namespace blink
 
 #endif // ObjectPaintProperties_h