[Contextual Search] Add support for crushed sprites and animate the search provider icon

chrome/browser/android/compositor/layer/crushed_sprite_layer.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 CHROME_BROWSER_ANDROID_COMPOSITOR_LAYER_CRUSHED_SPRITE_LAYER_H_
+#define CHROME_BROWSER_ANDROID_COMPOSITOR_LAYER_CRUSHED_SPRITE_LAYER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "cc/layers/content_layer_client.h"
+#include "chrome/browser/android/compositor/layer/layer.h"
+#include "ui/gfx/geometry/rect.h"
+
+namespace cc {
+class ContentLayerClient;
+class Layer;
+class PictureLayer;
+}
+
+namespace chrome {
+namespace android {
+
+// A layer which manages painting source rectangles from a crushed sprite sheet
+// into a PictureLayer. The frames in a crushed sprite sheet are represented by
+// a set of rectangles. Most frames consist of small rectangles representing the
+// change from the previous frame. Typically, the rectangles for the current
+// frame get painted on top of the previous frame.
+class CrushedSpriteLayer : public Layer, cc::ContentLayerClient {
+ public:
+  static scoped_refptr<CrushedSpriteLayer> Create();
+
+  // Sets the source bitmap and source and destination rectangles. Source
+  // rectangles from the source bitmap are painted to the destination
+  // rectangles. |paint_previous_frame| should be true if the current frame's
+  // rectangles should be painted on top of the previous frame.
+  void UpdateCrushedSprite(
+      const SkBitmap& src_bitmap,
+      const std::vector<std::pair<gfx::Rect, gfx::Rect>>& src_dst_rects,
+      bool paint_previous_frame);
+
+  // Layer override.
+  scoped_refptr<cc::Layer> layer() override;
+
+  // ContentLayerClient implementation.
+  void PaintContents(SkCanvas* canvas,
+                     const gfx::Rect& clip,
+                     PaintingControlSetting painting_control) override;
+  scoped_refptr<cc::DisplayItemList> PaintContentsToDisplayList(
+      const gfx::Rect& clip,
+      PaintingControlSetting painting_control) override;
+  bool FillsBoundsCompletely() const override;
+  size_t GetApproximateUnsharedMemoryUsage() const override;
+
+ protected:
+  CrushedSpriteLayer();
+  ~CrushedSpriteLayer() override;
+
+ private:
+  scoped_refptr<cc::PictureLayer> layer_;

[pedro (no code reviews), 2015/09/30 16:02:46]

Sorry I didn't notice this before, but it feels weird that this is a Layer that
returns another (picture) layer. Wouldn't it be possible to extend the
PictureImageLayer instead and use it (which extends PictureLayer and implements
the ContentLayerClient)?

In either case, I not familiar with the implementation of those classes, so it
would be good having someone more familiar with it reviewing this class and its
usage in ContextualSearchLayer.

[Theresa, 2015/10/01 01:57:31]

PictureImageLayer's constructor is private, so extending it would require
changes to that class. For now, I changed CrushedSpriteLayer to extend
PictureLayer and dropped this variable. There is some duplicate code between
PictureImageLayer and this new class, but not a whole lot, so for this first
pass I think it's okay. 

+  bool paint_previous_frame_;
+  skia::RefPtr<SkPicture> previous_frame_;
+  SkBitmap src_bitmap_;
+  std::vector<std::pair<gfx::Rect, gfx::Rect>> src_dst_rects_;
+
+  DISALLOW_COPY_AND_ASSIGN(CrushedSpriteLayer);
+};
+
+} // namespace android
+} // namespace chrome
+
+#endif  // CHROME_BROWSER_ANDROID_COMPOSITOR_LAYER_CRUSHED_SPRITE_LAYER_H_