First step of PaintInvalidator implementation

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

 // Copyright 2016 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 PaintInvalidator_h
 #define PaintInvalidator_h
 
-#include "core/layout/PaintInvalidationState.h"
-#include "wtf/Optional.h"
+#include "platform/geometry/LayoutRect.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class FrameView;
+class LayoutBoxModelObject;
 class LayoutObject;
+class PaintLayer;
 struct PaintPropertyTreeBuilderContext;
 
-// TODO(wangxianzhu): Move applicable PaintInvalidationState code into PaintInvalidator.
-using PaintInvalidatorContext = PaintInvalidationState;
+struct PaintInvalidatorContext {
+    PaintInvalidatorContext(const PaintPropertyTreeBuilderContext& treeBuilderContext)
+        : treeBuilderContext(treeBuilderContext) { }
+
+    PaintInvalidatorContext(const PaintPropertyTreeBuilderContext& treeBuilderContext, const PaintInvalidatorContext& parentContext)
+        : treeBuilderContext(treeBuilderContext)
+        , paintInvalidationContainer(parentContext.paintInvalidationContainer)
+        , paintInvalidationContainerForStackedContents(parentContext.paintInvalidationContainerForStackedContents)
+        , paintingLayer(parentContext.paintingLayer)
+    { }
+
+    // This method is temporary to adapt PaintInvalidatorContext and the legacy PaintInvalidationState
+    // for code shared by old code and new code.
+    virtual void mapLocalRectToPaintInvalidationBacking(const LayoutObject&, LayoutRect&) const;
+
+    const PaintPropertyTreeBuilderContext& treeBuilderContext;
+
+    enum ForcedSubtreeInvalidationFlag {
+        ForcedSubtreeInvalidationChecking = 1 << 0,
+        ForcedSubtreeInvalidationRectUpdate = 1 << 1,
+        ForcedSubtreeFullInvalidation = 1 << 2,
+        ForcedSubtreeFullInvalidationForStackedContents = 1 << 3,
+    };
+    unsigned forcedSubtreeInvalidationFlags = 0;
+
+    // The following fields can be null only before PaintInvalidator::updateContext().
+
+    // The current paint invalidation container for normal flow objects.
+    // It is the enclosing composited object.
+    const LayoutBoxModelObject* paintInvalidationContainer = nullptr;
+
+    // The current paint invalidation container for stacked contents (stacking contexts or positioned objects).
+    // It is the nearest ancestor composited object which establishes a stacking context.
+    // See Source/core/paint/README.md ### PaintInvalidationState for details on how stacked contents'
+    // paint invalidation containers differ.
+    const LayoutBoxModelObject* paintInvalidationContainerForStackedContents = nullptr;
+
+    PaintLayer* paintingLayer = nullptr;
+
+    LayoutRect oldBounds;
+    LayoutRect newBounds;
+    LayoutPoint oldLocation;
+    LayoutPoint newLocation;
+};
 
 class PaintInvalidator {
 public:
-    // TODO(wangxianzhu): Avoid Optional<> by using copy-and-update pattern for PaintInvalidatorContext.
-    void invalidatePaintIfNeeded(FrameView&, const PaintPropertyTreeBuilderContext&, Optional<PaintInvalidatorContext>&);
-    void invalidatePaintIfNeeded(const LayoutObject&, const PaintPropertyTreeBuilderContext&, const PaintInvalidatorContext&, Optional<PaintInvalidatorContext>&);
+    void invalidatePaintIfNeeded(FrameView&, PaintInvalidatorContext&);
+    void invalidatePaintIfNeeded(const LayoutObject&, PaintInvalidatorContext&);
 
     // Process objects needing paint invalidation on the next frame.
     // See the definition of PaintInvalidationDelayedFull for more details.
     void processPendingDelayedPaintInvalidations();
 
 private:
     Vector<const LayoutObject*> m_pendingDelayedPaintInvalidations;
 };
 
 } // namespace blink
 
 #endif // PaintInvalidator_h