New paint invalidation using paint property tree walk

third_party/WebKit/Source/core/layout/PaintInvalidationState.h

 // Copyright 2014 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 PaintInvalidationState_h
 #define PaintInvalidationState_h
 
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/transforms/AffineTransform.h"
 #include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 
 namespace blink {
 
 class LayoutBoxModelObject;
 class LayoutObject;
 class LayoutSVGModelObject;
 class LayoutView;
 class PaintLayer;
 
 // PaintInvalidationState is an optimization used during the paint
 // invalidation phase.
 //
 // This class is extremely close to LayoutState so see the documentation
 // of LayoutState for the class existence and performance benefits.
 //
 // The main difference with LayoutState is that it was customized for the
 // needs of the paint invalidation systems (keeping visual rectangles
 // instead of layout specific information).
 class PaintInvalidationState {
     DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
     WTF_MAKE_NONCOPYABLE(PaintInvalidationState);
 public:
-    PaintInvalidationState(PaintInvalidationState& next, LayoutBoxModelObject& layoutObject, const LayoutBoxModelObject& paintInvalidationContainer);
+    // For RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled.
+    PaintInvalidationState(const PaintInvalidationState* parent, const LayoutObject&, const LayoutBoxModelObject& paintInvalidationContainer, const LayoutPoint& paintOffset);

[chrishtr, 2016/03/11 21:30:00]

Would it be better/possible to just fold the necessary logic into
PrePaintTreeWalkContext rather than reusing this class?

[Xianzhu, 2016/03/11 22:01:47]

I believe it would be better, but it would need a big change on all paint
invalidation code. I plan the first step to reuse
LayoutObject::invalidatePaintIfNeeded() and let PrePaintTreeWalk create
PaintInvalidationStates accepted by invalidatePaintIfNeeded(). Paint
invalidation for spv2 may move all paint invalidation code into
PrePaintTreeWalk.

[chrishtr, 2016/03/11 22:08:18]

Couldn't you do it incrementally by creating PaintInvalidationState objects
every time just before calling invalidatePaintIfNeeded?

+
+    PaintInvalidationState(PaintInvalidationState& next, const LayoutBoxModelObject& layoutObject, const LayoutBoxModelObject& paintInvalidationContainer);
     PaintInvalidationState(PaintInvalidationState& next, const LayoutSVGModelObject& layoutObject);
 
     PaintInvalidationState(const LayoutView& layoutView, Vector<LayoutObject*>& pendingDelayedPaintInvalidations)
         : PaintInvalidationState(layoutView, pendingDelayedPaintInvalidations, nullptr) { }
     PaintInvalidationState(const LayoutView& layoutView, PaintInvalidationState& ownerPaintInvalidationState)
-        : PaintInvalidationState(layoutView, ownerPaintInvalidationState.m_pendingDelayedPaintInvalidations, &ownerPaintInvalidationState) { }
+        : PaintInvalidationState(layoutView, *ownerPaintInvalidationState.m_pendingDelayedPaintInvalidations, &ownerPaintInvalidationState) { }
 
     const LayoutRect& clipRect() const { return m_clipRect; }
     const LayoutSize& paintOffset() const { return m_paintOffset; }
     const AffineTransform& svgTransform() const { return m_svgTransform; }
 
     bool cachedOffsetsEnabled() const { return m_cachedOffsetsEnabled; }
     bool isClipped() const { return m_clipped; }
 
     bool forcedSubtreeInvalidationWithinContainer() const { return m_forcedSubtreeInvalidationWithinContainer; }
     void setForceSubtreeInvalidationWithinContainer() { m_forcedSubtreeInvalidationWithinContainer = true; }
 
     bool forcedSubtreeInvalidationRectUpdateWithinContainer() const { return m_forcedSubtreeInvalidationRectUpdateWithinContainer; }
     void setForceSubtreeInvalidationRectUpdateWithinContainer() { m_forcedSubtreeInvalidationRectUpdateWithinContainer = true; }
 
     const LayoutBoxModelObject& paintInvalidationContainer() const { return m_paintInvalidationContainer; }
 
     bool canMapToContainer(const LayoutBoxModelObject* container) const
     {
         return m_cachedOffsetsEnabled && container == &m_paintInvalidationContainer;
     }
 
     // Records |obj| as needing paint invalidation on the next frame. See the definition of PaintInvalidationDelayedFull for more details.
-    void pushDelayedPaintInvalidationTarget(LayoutObject& obj) { m_pendingDelayedPaintInvalidations.append(&obj); }
-    Vector<LayoutObject*>& pendingDelayedPaintInvalidationTargets() { return m_pendingDelayedPaintInvalidations; }
+    void pushDelayedPaintInvalidationTarget(LayoutObject& obj) { ASSERT(!RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled()); m_pendingDelayedPaintInvalidations->append(&obj); }
+    Vector<LayoutObject*>& pendingDelayedPaintInvalidationTargets() { ASSERT(!RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled()); return *m_pendingDelayedPaintInvalidations; }
 
     // Disable view clipping and scroll offset adjustment for paint invalidation of FrameView scrollbars.
     // TODO(wangxianzhu): Remove this when root-layer-scrolls launches.
     bool viewClippingAndScrollOffsetDisabled() const { return m_viewClippingAndScrollOffsetDisabled; }
     void setViewClippingAndScrollOffsetDisabled(bool b) { m_viewClippingAndScrollOffsetDisabled = b; }
 
     PaintLayer& enclosingSelfPaintingLayer(const LayoutObject&) const;
 
 private:
     PaintInvalidationState(const LayoutView&, Vector<LayoutObject*>& pendingDelayedPaintInvalidations, PaintInvalidationState* ownerPaintInvalidationState);
@@ skipping 17 matching lines @@
     // The current paint invalidation container.
     //
     // It is the enclosing composited object.
     const LayoutBoxModelObject& m_paintInvalidationContainer;
 
     // Transform from the initial viewport coordinate system of an outermost
     // SVG root to the userspace _before_ the relevant element. Combining this
     // with |m_paintOffset| yields the "final" offset.
     AffineTransform m_svgTransform;
 
-    Vector<LayoutObject*>& m_pendingDelayedPaintInvalidations;
+    Vector<LayoutObject*>* m_pendingDelayedPaintInvalidations;
 
     PaintLayer& m_enclosingSelfPaintingLayer;
 };
 
 } // namespace blink
 
 #endif // PaintInvalidationState_h