Preliminary paint property walk implementation for SPv2

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

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 25 matching lines @@
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/layout/HitTestRequest.h"
 #include "core/layout/LayoutObjectChildList.h"
 #include "core/layout/PaintInvalidationState.h"
 #include "core/layout/ScrollAlignment.h"
 #include "core/layout/SubtreeLayoutScope.h"
 #include "core/layout/api/HitTestAction.h"
 #include "core/layout/api/SelectionState.h"
 #include "core/layout/compositing/CompositingState.h"
 #include "core/layout/compositing/CompositingTriggers.h"
+#include "core/paint/ObjectPaintProperties.h"
 #include "core/style/ComputedStyle.h"
 #include "core/style/StyleInheritedData.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/CompositingReasons.h"
 #include "platform/graphics/PaintInvalidationReason.h"
 #include "platform/graphics/paint/DisplayItemClient.h"
 #include "platform/transforms/TransformationMatrix.h"
 
 namespace blink {
@@ skipping 116 matching lines @@
 // because only boxes implementing the full box model have a need for them.
 // Because LayoutBlockFlow's intrinsic widths rely on the underlying text
 // content, LayoutBlockFlow may call LayoutText::computePreferredLogicalWidths.
 //
 // The 2 widths are computed lazily during layout when the getters are called.
 // The computation is done by calling computePreferredLogicalWidths() behind the
 // scene. The boolean used to control the lazy recomputation is
 // preferredLogicalWidthsDirty.
 //
 // See the individual getters below for more details about what each width is.
-class CORE_EXPORT LayoutObject : public ImageResourceClient {
+class CORE_EXPORT LayoutObject : public ImageResourceClient, public ObjectPaintProperties::Owner {

[chrishtr, 2015/10/14 17:30:28]

We went to great lengths to avoid inheriting from DisplayItemClient, to avoid
making layout objects bigger and have more virtual function calls. Does that
reasoning apply in this case or not?

[trchen, 2015/10/14 22:51:13]

This guy has no virtual functions, it is more like a mix-in class than an
interface.
I checked with C++ spec again, an empty class takes 1 byte when used as a leaf
class, but may take 0 byte when inherited. (LayoutObject size check should catch
this if not 0.)

     friend class LayoutObjectChildList;
     WTF_MAKE_NONCOPYABLE(LayoutObject);
 public:
     // Anonymous objects should pass the document as their node, and they will then automatically be
     // marked as anonymous in the constructor.
     explicit LayoutObject(Node*);
     ~LayoutObject() override;
 
     // Returns the name of the layout object.
     virtual const char* name() const = 0;
@@ skipping 1813 matching lines @@
 void showTree(const blink::LayoutObject*);
 void showLineTree(const blink::LayoutObject*);
 void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 void showLayoutTree(const blink::LayoutObject* object1, const blink::LayoutObject* object2);
 
 #endif
 
 #endif // LayoutObject_h