Implement DeviceOrientation API on Windows

content/browser/device_orientation/data_fetcher_impl_win.h

+// Copyright (c) 2013 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_DEVICE_ORIENTATION_DATA_FETCHER_IMPL_WIN_H_
+#define CONTENT_BROWSER_DEVICE_ORIENTATION_DATA_FETCHER_IMPL_WIN_H_
+
+#include <SensorsApi.h>
+
+#include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
+#include "base/win/scoped_comptr.h"
+#include "content/browser/device_orientation/data_fetcher.h"
+#include "content/browser/device_orientation/device_data.h"
+
+namespace content {
+
+class Orientation;
+
+// Windows implementation of DeviceOrientation API.
+// The SensorEventSink is installed to Windows sensor thread to listen for
+// sensor's data. Upon each notification, DataFetcherImplWin buffers the data.
+// Then Chrome sensor polling thread pulls the buffered data via GetDeviceData.
+// The Inclinometer 3D sensor (SENSOR_TYPE_INCLINOMETER_3D) is used to get the
+// orientation data.
+
+class DataFetcherImplWin : public DataFetcher {
+ public:
+  virtual ~DataFetcherImplWin();
+
+  // Factory function. It returns NULL on error.
+  // The created object listens for events for the whole lifetime.
+  static DataFetcher* Create();
+
+  // Implement DataFetcher.
+  virtual const DeviceData* GetDeviceData(DeviceData::Type type) OVERRIDE;
+
+ private:
+  class SensorEventSink;
+  friend SensorEventSink;
+
+  DataFetcherImplWin();
+  bool Initialize();
+  void OnOrientationData(Orientation* orientation);
+  const Orientation* GetOrientation();
+
+  base::win::ScopedComPtr<ISensor> sensor_;
+
+  // Value returned by GetDeviceData.
+  scoped_refptr<Orientation> current_orientation_;
+
+  // The 1-element buffer follows DataFetcherImplAndroid implementation.
+  // It is written by OnOrientationData and read by GetDeviceData.
+  base::Lock next_orientation_lock_;
+  scoped_refptr<Orientation> next_orientation_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataFetcherImplWin);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_DEVICE_ORIENTATION_DATA_FETCHER_IMPL_WIN_H_