Avoid paintInvalidationContainer parameter of invalidatePaintIfNeeded()

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/geometry/LayoutRect.h"
 #include "platform/transforms/AffineTransform.h"
 #include "wtf/Allocator.h"
@@ skipping 13 matching lines @@
 // 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);
-    PaintInvalidationState(PaintInvalidationState& next, const LayoutSVGModelObject& layoutObject);
+    PaintInvalidationState(const PaintInvalidationState& parentState, const LayoutObject&);
 
+    // TODO(wangxianzhu): This is temporary for positioned object whose paintInvalidationContainer is different from
+    // the one we find during tree walk. Remove this after we fix the issue with tree walk in DOM-order.
+    PaintInvalidationState(const PaintInvalidationState& parentState, const LayoutBoxModelObject&, const LayoutBoxModelObject& paintInvalidationContainer);
+
+    // For root LayoutView.
     PaintInvalidationState(const LayoutView& layoutView, Vector<LayoutObject*>& pendingDelayedPaintInvalidations)
         : PaintInvalidationState(layoutView, pendingDelayedPaintInvalidations, nullptr) { }
-    PaintInvalidationState(const LayoutView& layoutView, PaintInvalidationState& ownerPaintInvalidationState)
+    // For LayoutView in a sub-frame.
+    PaintInvalidationState(const LayoutView& layoutView, const PaintInvalidationState& ownerPaintInvalidationState)
         : PaintInvalidationState(layoutView, ownerPaintInvalidationState.m_pendingDelayedPaintInvalidations, &ownerPaintInvalidationState) { }
 
+    // When a PaintInvalidationState is constructed, it just updates paintInvalidationContainer and
+    // copy cached paintOffset and clip from the parent PaintInvalidationContainer.
+    // This PaintInvalidationContainer can be used to invalidate the current object.
+    //
+    // After invalidation of the current object, before invalidation of the subtrees,
+    // this method must be called to make this PaintInvalidationState suitable for
+    // paint invalidation of children.
+    void updatePaintOffsetAndClipForChildren();
+
     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 canMapToAncestor(const LayoutBoxModelObject* ancestor) const
     {
         return m_cachedOffsetsEnabled && ancestor == &m_paintInvalidationContainer;
     }
     void mapObjectRectToAncestor(const LayoutObject&, const LayoutBoxModelObject* ancestor, LayoutRect&) const;
 
     // 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) const { m_pendingDelayedPaintInvalidations.append(&obj); }
+    Vector<LayoutObject*>& pendingDelayedPaintInvalidationTargets() const { 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);
+    PaintInvalidationState(const LayoutView&, Vector<LayoutObject*>& pendingDelayedPaintInvalidations, const PaintInvalidationState* ownerPaintInvalidationState);
 
     void applyClipIfNeeded(const LayoutObject&);
     void addClipRectRelativeToPaintOffset(const LayoutSize& clipSize);
 
     friend class ForceHorriblySlowRectMapping;
 
+    const LayoutObject& m_layoutObject;

[chrishtr, 2016/03/17 20:44:54]

This name is not so clear. Add a comment or consider a better name.

[Xianzhu, 2016/03/17 21:11:43]

Renamed to m_currentObject.

I'm working on another patch to move all fast-path paint invalidation geometry
mapping code into PaintInvalidationState, and cleanup LayoutObject's geometry
mapping methods with optional PaintInvalidationState parameters. With the patch,
the meaning of m_currentObject will be clearer.

+
     bool m_clipped;
     mutable bool m_cachedOffsetsEnabled;
     bool m_forcedSubtreeInvalidationWithinContainer;
     bool m_forcedSubtreeInvalidationRectUpdateWithinContainer;
     bool m_viewClippingAndScrollOffsetDisabled;
 
     LayoutRect m_clipRect;
 
     // x/y offset from paint invalidation container. Includes relative positioning and scroll offsets.
     LayoutSize m_paintOffset;
 
     // 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;
 
     PaintLayer& m_enclosingSelfPaintingLayer;
+
+#if ENABLE(ASSERT)
+    bool m_didUpdatePaintOffsetAndClipForChildren;
+#endif
+};
+
+// Suspends the PaintInvalidationState cached offset and clipRect optimization. Used under transforms
+// that cannot be represented by PaintInvalidationState (common in SVG) and when paint invalidation
+// containers don't follow the common tree-walk algorithm (e.g. when an absolute positioned descendant
+// is nested under a relatively positioned inline-block child).
+class ForceHorriblySlowRectMapping {
+    STACK_ALLOCATED();
+    WTF_MAKE_NONCOPYABLE(ForceHorriblySlowRectMapping);
+public:
+    ForceHorriblySlowRectMapping(const PaintInvalidationState* paintInvalidationState)
+        : m_paintInvalidationState(paintInvalidationState)
+        , m_didDisable(m_paintInvalidationState && m_paintInvalidationState->cachedOffsetsEnabled())
+    {
+        if (m_paintInvalidationState)
+            m_paintInvalidationState->m_cachedOffsetsEnabled = false;
+    }
+
+    ~ForceHorriblySlowRectMapping()
+    {
+        if (m_didDisable)
+            m_paintInvalidationState->m_cachedOffsetsEnabled = true;
+    }
+private:
+    const PaintInvalidationState* m_paintInvalidationState;
+    bool m_didDisable;
 };
 
 } // namespace blink
 
 #endif // PaintInvalidationState_h