Motown: Add examples/media_test, a command line media player app.

examples/media_test/media_test.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 EXAMPLES_MEDIA_TEST_MEDIA_TEST_H_
+#define EXAMPLES_MEDIA_TEST_MEDIA_TEST_H_
+
+#include "base/macros.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "mojo/services/media/common/interfaces/rate_control.mojom.h"
+#include "mojo/services/media/control/interfaces/media_factory.mojom.h"
+#include "mojo/services/media/control/interfaces/media_player.mojom.h"
+
+namespace examples {

[johngro, 2016/03/21 22:10:47]

if you want to save the need to say mojo::media:: all over the place, you could
put this project into ::mojo::media::examples instead of just ::examples.

If you prefer the explicit nature of calling out the media subsystem as you use
it, you could also put this in ::mojo::examples (meaning you should be able to
say media::MyThing instead of mojo::media::MyThing)

[dalesat, 2016/03/21 23:58:35]

Done.

+
+// Model for media test application.
+class MediaTest {
+ public:
+  using UpdateCallback = std::function<void()>;
+
+  static std::unique_ptr<MediaTest> Create(
+      mojo::ApplicationImpl* app,
+      const std::string& input_file_name);
+
+  ~MediaTest();
+
+  // Registers a callback signalling that the app should update its view.
+  void RegisterUpdateCallback(const UpdateCallback& callback);
+
+  // Starts playback.
+  void Play();
+
+  // Pauses playback.
+  void Pause();
+
+  // Seeks to the position indicated in nanoseconds from the start of the media.
+  void Seek(int64_t position_ns);
+
+  // Returns the current state of the player.
+  mojo::media::MediaState state() const;
+
+  // Returns the current presentation time in nanoseconds.
+  int64_t position_ns() const;
+
+  // Returns the current media metadata, if there is any.
+  const mojo::media::MediaMetadataPtr& metadata() const;
+
+ private:
+  MediaTest(mojo::ApplicationImpl* app, const std::string& input_file_name);
+
+  // Handles a status update from the player. When called with the default
+  // argument values, initiates status updates.
+  void HandleStatusUpdates(
+      uint64_t version = 0,

[johngro, 2016/03/21 22:10:46]

sanity check, 0 is a special value for version which will never be reported in a
status update by a mojo::media::MedaiPlayer, correct?

If so, it might be good to define this in the .mojom interface and then use the
constant's symbol instead of using 0.

[dalesat, 2016/03/21 23:58:35]

Excellent point. I've added this to three mojom files.

+      mojo::media::MediaPlayerStatusPtr status = nullptr);
+
+  mojo::media::MediaPlayerPtr media_player_;
+  mojo::media::MediaState state_;
+  mojo::media::TimelineTransformPtr transform_;
+  mojo::media::MediaMetadataPtr metadata_;
+  UpdateCallback update_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaTest);
+};
+
+}  // namespace examples
+
+#endif  // EXAMPLES_MEDIA_TEST_MEDIA_TEST_H_