cast: support cursor rendering for tab capture

content/browser/media/capture/cursor_renderer_aura.h

+// Copyright (c) 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 CONTENT_BROWSER_MEDIA_CAPTURE_CURSOR_RENDERER_AURA_H_
+#define CONTENT_BROWSER_MEDIA_CAPTURE_CURSOR_RENDERER_AURA_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "content/browser/media/capture/cursor_renderer.h"
+#include "content/common/content_export.h"
+#include "media/base/video_frame.h"
+#include "skia/ext/image_operations.h"
+#include "ui/aura/window.h"
+#include "ui/base/cursor/cursor.h"
+#include "ui/events/event_handler.h"
+#include "ui/gfx/geometry/point.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+#include "ui/gfx/native_widget_types.h"
+
+namespace content {
+
+// Tracks state for making decisions on cursor display on a captured video
+// frame
+class CONTENT_EXPORT CursorRendererAura :
+    public CursorRenderer,
+    public ui::EventHandler,
+    public aura::WindowObserver {
+ public:
+  explicit CursorRendererAura(gfx::NativeWindow window);
+  ~CursorRendererAura() override;

[miu, 2015/10/23 01:55:12]

For all these methods, try to use 'final' instead of 'override' to help the
compiler/linked optimize virtual method calls in release builds.

[Irfan, 2015/10/26 23:10:31]

Done.

+  void Clear() override;

[miu, 2015/10/23 01:55:12]

style: These three methods should be headed by a comment like so:

  // CursorRenderer implementation.
  void Clear() final;
  bool Update(...) final;
  void RenderOnVideoFrame(...) final;

...and ditto for OnMouseEvent() and OnWindowDestroying() below.

[Irfan, 2015/10/26 23:10:31]

Done.

+  bool Update(const gfx::Rect& region_in_frame) override;
+  void RenderOnVideoFrame(
+      const scoped_refptr<media::VideoFrame>& target) const override;
+
+  // Overridden from ui::EventHandler to make decision on when

[miu, 2015/10/23 01:55:12]

style: No need to document overridden interface methods.  Instead, just:

  // ui::EventHandler overrides.
  void OnMouseEvent(...) final;

...and:

  // aura::WindowObserver overrides.
  void OnWindowDestroying(...) final;

[Irfan, 2015/10/26 23:10:31]

Done.

+  // cursor gets rendered on a captured video frame
+  void OnMouseEvent(ui::MouseEvent* event) override;
+
+  // Overridden from aura::WindowObserver to clean up before window is destroyed
+  void OnWindowDestroying(aura::Window* window) override;
+
+  base::WeakPtr<CursorRenderer> GetWeakPtr() override;

[miu, 2015/10/23 01:55:12]

This should be next to the other three methods being overridden for the
CursorRenderer interface.

[Irfan, 2015/10/26 23:10:31]

Done.

+ private:
+  ui::Cursor last_cursor_;

[miu, 2015/10/23 01:55:12]

Please add a comment for these four members.  Like:

  // Snapshot of cursor, source size, position, and cursor bitmap; as of the
last call to Update().

[Irfan, 2015/10/26 23:10:31]

Done.

+  gfx::Size window_size_when_cursor_last_updated_;
+  gfx::Point cursor_position_in_frame_;
+  SkBitmap scaled_cursor_bitmap_;
+  gfx::NativeView window_;

[miu, 2015/10/23 01:55:12]

nit: |window_| should go first since it's injected via the ctor.

[Irfan, 2015/10/26 23:10:31]

Done.

+
+  enum {

[miu, 2015/10/23 01:55:12]

Consider moving these values to the CursorRenderer class, since they will also
be needed for the Mac implementation.

[Irfan, 2015/10/26 23:10:31]

Done.

+    // Minium movement before cursor is rendered on frame

[miu, 2015/10/23 01:55:12]

style nit: In Chromium code, all comments must be complete sentences (and end
with a period).  Please fix here, and in all other files.

[Irfan, 2015/10/26 23:10:31]

Done.

+    MIN_MOVEMENT_PIXELS = 15,
+    // Maximum idle time allowed before we stop rendering the cursor
+    // on frame
+    MAX_IDLE_TIME_SECONDS = 2
+  };
+
+  base::TimeDelta last_mouse_movement_timestamp_;

[miu, 2015/10/23 01:55:12]

Short comment needed here too about when these are updated and how they are
used.

[Irfan, 2015/10/26 23:10:31]

Done.

+  float last_mouse_position_x_;
+  float last_mouse_position_y_;
+  bool cursor_displayed_;
+
+  base::WeakPtrFactory<CursorRendererAura> weak_factory_;
+  DISALLOW_COPY_AND_ASSIGN(CursorRendererAura);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEDIA_CAPTURE_CURSOR_RENDERER_AURA_H_