Implement the algorithm to test merging and overlap in PaintArtifactCompositor.

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h

 // Copyright 2015 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 PaintArtifactCompositor_h
 #define PaintArtifactCompositor_h
 
 #include "base/memory/ref_counted.h"
 #include "platform/PlatformExport.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsLayerClient.h"
 #include "platform/graphics/paint/PaintController.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PtrUtil.h"
 #include "wtf/Vector.h"
 #include <memory>
 
 namespace cc {
 class Layer;
 }
 
 namespace gfx {
 class Vector2dF;
 }
 
 namespace blink {
 
 class JSONObject;
+class LayoutView;
 class PaintArtifact;
 class WebLayer;
 struct PaintChunk;
 
+struct PendingLayer {
+  PendingLayer(const PaintChunk& firstPaintChunk) : knownToBeOpaque(false) {
+    add(firstPaintChunk);
+  }
+
+  void add(const PaintChunk& paintChunk) {
+    paintChunks.append(paintChunk);
+    bounds.unite(paintChunk.bounds);
+    knownToBeOpaque = knownToBeOpaque && paintChunk.knownToBeOpaque;
+  }
+
+  FloatRect bounds;
+  Vector<PaintChunk> paintChunks;
+  bool knownToBeOpaque;
+};
+
 // Responsible for managing compositing in terms of a PaintArtifact.
 //
 // Owns a subtree of the compositor layer tree, and updates it in response to
 // changes in the paint artifact.
 //
 // PaintArtifactCompositor is the successor to PaintLayerCompositor, reflecting
 // the new home of compositing decisions after paint in Slimming Paint v2.
 class PLATFORM_EXPORT PaintArtifactCompositor {
   WTF_MAKE_NONCOPYABLE(PaintArtifactCompositor);
 
@@ skipping 32 matching lines @@
   void resetTrackedRasterInvalidations();
   bool hasTrackedRasterInvalidations() const;
 
   std::unique_ptr<JSONObject> layersAsJSON(LayerTreeFlags) const;
 
  private:
   PaintArtifactCompositor();
 
   class ContentLayerClientImpl;
 
+  void collectPendingLayers(const Vector<PaintChunk>& paintChunks,
+                            Vector<PendingLayer>& pendingLayers);
+
   // Builds a leaf layer that represents a single paint chunk.
   // Note: cc::Layer API assumes the layer bounds start at (0, 0), but the
   // bounding box of a paint chunk does not necessarily start at (0, 0) (and
   // could even be negative). Internally the generated layer translates the
   // paint chunk to align the bounding box to (0, 0) and return the actual
   // origin of the paint chunk in the |layerOffset| outparam.
-  scoped_refptr<cc::Layer> layerForPaintChunk(
+  scoped_refptr<cc::Layer> compositedLayerForPendingLayer(
       const PaintArtifact&,
-      const PaintChunk&,
+      const PendingLayer&,
       gfx::Vector2dF& layerOffset,
       Vector<std::unique_ptr<ContentLayerClientImpl>>& newContentLayerClients,
-      RasterInvalidationTracking*);
+      RasterInvalidationTrackingMap<const PaintChunk>*);
 
   // Finds a client among the current vector of clients that matches the paint
   // chunk's id, or otherwise allocates a new one.
   std::unique_ptr<ContentLayerClientImpl> clientForPaintChunk(
       const PaintChunk&,
       const PaintArtifact&);
 
   scoped_refptr<cc::Layer> m_rootLayer;
   std::unique_ptr<WebLayer> m_webLayer;
   Vector<std::unique_ptr<ContentLayerClientImpl>> m_contentLayerClients;
 
   bool m_extraDataForTestingEnabled = false;
   std::unique_ptr<ExtraDataForTesting> m_extraDataForTesting;
   friend class StubChromeClientForSPv2;
 
   bool m_isTrackingRasterInvalidations;
 };
 
 }  // namespace blink
 
 #endif  // PaintArtifactCompositor_h