Rotate screen in response to accelerator or device orientation sensors.

athena/system/orientation_controller.h

+// Copyright 2014 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 ATHENA_SYSTEM_ORIENTATION_CONTROLLER_H_
+#define ATHENA_SYSTEM_ORIENTATION_CONTROLLER_H_
+
+#include "athena/system/device_socket_listener.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "ui/gfx/display.h"
+
+namespace base {
+class FilePath;
+class FilePathWatcher;
+class TaskRunner;
+}
+
+namespace athena {
+
+// Monitors accelerometers, detecting orientation changes. When a change is
+// detected rotates the root window to match.
+class OrientationController
+    : public DeviceSocketListener,
+      public base::RefCountedThreadSafe<OrientationController> {
+ public:
+  OrientationController(scoped_refptr<base::TaskRunner> io_task_runner);
+
+ private:
+  friend class base::RefCountedThreadSafe<OrientationController>;
+
+  virtual ~OrientationController();
+
+  // Watch for the socket path to be created, called on the IO thread.
+  void WatchForSocketPathOnIO();
+  void OnFilePathChangedOnIO(const base::FilePath& path, bool error);
+
+  // Overridden from device::DeviceSocketListener:
+  virtual void OnDataAvailableOnIO(const void* data) OVERRIDE;
+
+  // Rotates the display to |rotation|, called on the UI thread.
+  void RotateOnUI(gfx::Display::Rotation rotation);
+
+  // The last configured rotation.
+  gfx::Display::Rotation current_rotation_;
+
+  // The timestamp of the last applied orientation change.
+  int64_t last_orientation_change_time_;
+
+  // A task runner for the UI thread.
+  scoped_refptr<base::TaskRunner> ui_task_runner_;
+
+  // File path watcher used to detect when sensors are present.
+  scoped_ptr<base::FilePathWatcher> watcher_;
+
+  base::WeakPtrFactory<OrientationController> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(OrientationController);
+};
+
+}  // namespace athena
+
+#endif  // ATHENA_SYSTEM_ORIENTATION_CONTROLLER_H_