Subtree caching implementation in blink-core

Source/core/paint/DeprecatedPaintLayer.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 91 matching lines @@
     String debugName() const;
 
     LayoutBoxModelObject* layoutObject() const { return m_layoutObject; }
     LayoutBox* layoutBox() const { return m_layoutObject && m_layoutObject->isBox() ? toLayoutBox(m_layoutObject) : 0; }
     DeprecatedPaintLayer* parent() const { return m_parent; }
     DeprecatedPaintLayer* previousSibling() const { return m_previous; }
     DeprecatedPaintLayer* nextSibling() const { return m_next; }
     DeprecatedPaintLayer* firstChild() const { return m_first; }
     DeprecatedPaintLayer* lastChild() const { return m_last; }
 
-    const DeprecatedPaintLayer* compositingContainer() const;
+    // TODO(wangxianzhu): Find a better name for it. 'paintContainer' might be good but
+    // we can't use it for now because it conflicts with PaintInfo::paintContainer.

[chrishtr, 2015/08/27 04:29:48]

How about stackingContainerForPaint()? With a comment saying that it's either a
stacking context or acts like one in the context
of the css 2.1 painting algorithm?

[Xianzhu, 2015/08/27 16:38:02]

stackingContainerForPaint seems incomplete, because for a
non-treated-as-stacking-context layer, the function returns the parent layer of
any kind, including non-stacking-context overflow-scroll layer.

A description might be: the ancestor layer whose paintLayer method will directly
call this layer's paintLayer method.

+    DeprecatedPaintLayer* compositingContainer() const;
 
     void addChild(DeprecatedPaintLayer* newChild, DeprecatedPaintLayer* beforeChild = 0);
     DeprecatedPaintLayer* removeChild(DeprecatedPaintLayer*);
 
     void removeOnlyThisLayer();
     void insertOnlyThisLayer();
 
     void styleChanged(StyleDifference, const ComputedStyle* oldStyle);
 
     // FIXME: Many people call this function while it has out-of-date information.
@@ skipping 407 matching lines @@
     };
 
     enum TransparencyClipBoxMode {
         DescendantsOfTransparencyClipBox,
         RootOfTransparencyClipBox
     };
 
     static LayoutRect transparencyClipBox(const DeprecatedPaintLayer*, const DeprecatedPaintLayer* rootLayer, TransparencyClipBoxBehavior transparencyBehavior,
         TransparencyClipBoxMode transparencyMode, GlobalPaintFlags = GlobalPaintNormalPhase);
 
+    bool needsRepaint() const { return m_needsRepaint; }
+    void setNeedsRepaint();
+    void clearNeedsRepaint() { m_needsRepaint = false; }
+
 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();
@@ skipping 52 matching lines @@
     // Both updates the status, and returns true if descendants of this have 3d.
     bool update3DTransformedDescendantStatus();
 
     void updateOrRemoveFilterClients();
 
     void updatePaginationRecursive(bool needsPaginationUpdate = false);
     void clearPaginationRecursive();
 
     void blockSelectionGapsBoundsChanged();
 
+    void markCompositingContainerChainForChildNeedsRepaint();
+
     DeprecatedPaintLayerType m_layerType;
 
     // Self-painting layer is an optimization where we avoid the heavy Layer painting
     // machinery for a Layer allocated only to handle the overflow clip case.
     // FIXME(crbug.com/332791): Self-painting layer should be merged into the overflow-only concept.
     unsigned m_isSelfPaintingLayer : 1;
 
     // If have no self-painting descendants, we don't have to walk our children during painting. This can lead to
     // significant savings, especially if the tree has lots of non-self-painting layers grouped together (e.g. table cells).
     mutable unsigned m_hasSelfPaintingLayerDescendant : 1;
@@ skipping 31 matching lines @@
     // as opposed to the tree formed by the z-order and normal flow lists).
     unsigned m_hasNonCompositedChild : 1;
 
     // Should be for stacking contexts having unisolated blending descendants.
     unsigned m_shouldIsolateCompositedDescendants : 1;
 
     // True if this layout layer just lost its grouped mapping due to the CompositedDeprecatedPaintLayerMapping being destroyed,
     // and we don't yet know to what graphics layer this Layer will be assigned.
     unsigned m_lostGroupedMapping : 1;
 
+    unsigned m_needsRepaint : 1;
+
     LayoutBoxModelObject* m_layoutObject;
 
     DeprecatedPaintLayer* m_parent;
     DeprecatedPaintLayer* m_previous;
     DeprecatedPaintLayer* m_next;
     DeprecatedPaintLayer* m_first;
     DeprecatedPaintLayer* m_last;
 
     // Our current relative position offset.
     LayoutSize m_offsetForInFlowPosition;
@@ skipping 46 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::DeprecatedPaintLayer*);
 void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif // Layer_h