Adapt and reland old position sticky implementation

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

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 246 matching lines @@
     LayoutRect rect() const { return LayoutRect(location(), LayoutSize(size())); }
 
     bool isRootLayer() const { return m_isRootLayer; }
 
     PaintLayerCompositor* compositor() const;
 
     // Notification from the layoutObject that its content changed (e.g. current frame of image changed).
     // Allows updates of layer content without invalidating paint.
     void contentChanged(ContentChangeType);
 
+    void updateLayerPosition();
+
     void updateLayerPositionsAfterLayout();
     void updateLayerPositionsAfterOverflowScroll(const DoubleSize& scrollDelta);
 
     PaintLayer* enclosingPaginationLayer() const { return m_rareData ? m_rareData->enclosingPaginationLayer : nullptr; }
 
     void updateTransformationMatrix();
     PaintLayer* renderingContextRoot();
 
     LayoutSize offsetForInFlowPosition() const { return m_rareData ? m_rareData->offsetForInFlowPosition : LayoutSize(); }
 
@@ skipping 243 matching lines @@
         IntRect clippedAbsoluteBoundingBox;
         const LayoutObject* clippingContainer;
     };
 
     class RareAncestorDependentCompositingInputs {
     public:
         RareAncestorDependentCompositingInputs()
             : opacityAncestor(nullptr)
             , transformAncestor(nullptr)
             , filterAncestor(nullptr)
+            , ancestorOverflowLayer(nullptr)
             , ancestorScrollingLayer(nullptr)
             , nearestFixedPositionLayer(nullptr)
             , scrollParent(nullptr)
             , clipParent(nullptr)
         { }
 
-        bool isDefault() const { return !opacityAncestor && !transformAncestor && !filterAncestor && !ancestorScrollingLayer && !nearestFixedPositionLayer && !scrollParent && !clipParent; }
+        bool isDefault() const { return !opacityAncestor && !transformAncestor && !filterAncestor && !ancestorOverflowLayer && !ancestorScrollingLayer && !nearestFixedPositionLayer && !scrollParent && !clipParent; }
 
         const PaintLayer* opacityAncestor;
         const PaintLayer* transformAncestor;
         const PaintLayer* filterAncestor;
+
+        // The first ancestor having a non visible overflow.
+        const PaintLayer* ancestorOverflowLayer;
+
+        // The fist ancestor which can scroll. This is a subset of the
+        // ancestorOverflowLayer chain where the scrolling layer is visible and
+        // has a larger scroll content than its bounds.
         const PaintLayer* ancestorScrollingLayer;
         const PaintLayer* nearestFixedPositionLayer;
 
         // A scroll parent is a compositor concept. It's only needed in blink
         // because we need to use it as a promotion trigger. A layer has a
         // scroll parent if neither its compositor scrolling ancestor, nor any
         // other layer scrolled by this ancestor, is a stacking ancestor of this
         // layer. Layers with scroll parents must be scrolled with the main
         // scrolling layer by the compositor.
         const PaintLayer* scrollParent;
@@ skipping 18 matching lines @@
 
     void updateAncestorDependentCompositingInputs(const AncestorDependentCompositingInputs&, const RareAncestorDependentCompositingInputs&, bool hasAncestorWithClipPath);
     void updateDescendantDependentCompositingInputs(bool hasDescendantWithClipPath, bool hasNonIsolatedDescendantWithBlendMode);
     void didUpdateCompositingInputs();
 
     IntRect clippedAbsoluteBoundingBox() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_ancestorDependentCompositingInputs.clippedAbsoluteBoundingBox; }
     const PaintLayer* opacityAncestor() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->opacityAncestor : nullptr; }
     const PaintLayer* transformAncestor() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->transformAncestor : nullptr; }
     const PaintLayer* filterAncestor() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->filterAncestor : nullptr; }
     const LayoutObject* clippingContainer() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_ancestorDependentCompositingInputs.clippingContainer; }
+    const PaintLayer* ancestorOverflowLayer() const { return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->ancestorOverflowLayer : nullptr; }
     const PaintLayer* ancestorScrollingLayer() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->ancestorScrollingLayer : nullptr; }
     const PaintLayer* nearestFixedPositionLayer() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->nearestFixedPositionLayer : nullptr; }
     const PaintLayer* scrollParent() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->scrollParent : nullptr; }
     const PaintLayer* clipParent() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_rareAncestorDependentCompositingInputs ? m_rareAncestorDependentCompositingInputs->clipParent : nullptr; }
     bool hasAncestorWithClipPath() const { ASSERT(!m_needsAncestorDependentCompositingInputsUpdate); return m_hasAncestorWithClipPath; }
     bool hasDescendantWithClipPath() const { ASSERT(!m_needsDescendantDependentCompositingInputsUpdate); return m_hasDescendantWithClipPath; }
     bool hasNonIsolatedDescendantWithBlendMode() const;
 
     bool lostGroupedMapping() const { ASSERT(isAllowedToQueryCompositingState()); return m_lostGroupedMapping; }
     void setLostGroupedMapping(bool b) { m_lostGroupedMapping = b; }
@@ skipping 91 matching lines @@
     void clearClipRectsCache() const { m_clipRectsCache.clear(); }
 
 private:
     // Bounding box in the coordinates of this layer.
     LayoutRect logicalBoundingBox() const;
 
     bool hasOverflowControls() const;
 
     void dirtyAncestorChainHasSelfPaintingLayerDescendantStatus();
 
-    // Returns true if the position changed.
-    bool updateLayerPosition();
-
     void updateLayerPositionRecursive();
     void updateLayerPositionsAfterScrollRecursive(const DoubleSize& scrollDelta, bool paintInvalidationContainerWasScrolled);
 
     void setNextSibling(PaintLayer* next) { m_next = next; }
     void setPreviousSibling(PaintLayer* prev) { m_previous = prev; }
     void setFirstChild(PaintLayer* first) { m_first = first; }
     void setLastChild(PaintLayer* last) { m_last = last; }
 
     void updateHasSelfPaintingLayerDescendant() const;
     PaintLayer* hitTestLayer(PaintLayer* rootLayer, PaintLayer* containerLayer, HitTestResult&,
@@ skipping 159 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::PaintLayer*);
 void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif // Layer_h