chromeos/accelerometer/accelerometer_reader.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
   6 #define CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
   7
   8 #include "base/memory/ref_counted.h"
   9 #include "base/observer_list_threadsafe.h"
  10 #include "chromeos/accelerometer/accelerometer_types.h"
  11 #include "chromeos/chromeos_export.h"
  12
  13 namespace base {
  14 template <typename T>
  15 struct DefaultSingletonTraits;
  16
  17 class SequencedTaskRunner;
  18 }
  19
  20 namespace chromeos {
  21
  22 class AccelerometerFileReader;
  23
  24 // Reads an accelerometer device and reports data back to an
  25 // AccelerometerDelegate.
  26 class CHROMEOS_EXPORT AccelerometerReader {
  27  public:
  28   // The time to wait between reading the accelerometer.
  29   static const int kDelayBetweenReadsMs;
  30
  31   // An interface to receive data from the AccelerometerReader.
  32   class Observer {
  33    public:
  34     virtual void OnAccelerometerUpdated(
  35         scoped_refptr<const AccelerometerUpdate> update) = 0;
  36
  37    protected:
  38     virtual ~Observer() {}
  39   };
  40
  41   static AccelerometerReader* GetInstance();
  42
  43   void Initialize(
  44       scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner);
  45
  46   // Add/Remove observers.
  47   void AddObserver(Observer* observer);
  48   void RemoveObserver(Observer* observer);
  49
  50  protected:
  51   AccelerometerReader();
  52   virtual ~AccelerometerReader();
  53
  54  private:
  55   friend struct base::DefaultSingletonTraits<AccelerometerReader>;
  56
  57   // Worker that will run on the base::SequencedTaskRunner provided to
  58   // Initialize. It will determine accelerometer configuration, read the data,
  59   // and notify observers.
  60   scoped_refptr<AccelerometerFileReader> accelerometer_file_reader_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
  63 };
  64
  65 }  // namespace chromeos
  66
  67 #endif  // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_