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/memory/weak_ptr.h"
  10 #include "base/observer_list.h"
  11 #include "chromeos/accelerometer/accelerometer_types.h"
  12 #include "chromeos/chromeos_export.h"
  13
  14 template <typename T>
  15 struct DefaultSingletonTraits;
  16
  17 namespace base {
  18 class TaskRunner;
  19 }
  20
  21 namespace chromeos {
  22
  23 // Reads an accelerometer device and reports data back to an
  24 // AccelerometerDelegate.
  25 class CHROMEOS_EXPORT AccelerometerReader {
  26  public:
  27   // Configuration structure for accelerometer device.
  28   struct ConfigurationData {
  29     ConfigurationData();
  30     ~ConfigurationData();
  31
  32     // Number of accelerometers on device.
  33     size_t count;
  34
  35     // Length of accelerometer updates.
  36     size_t length;
  37
  38     // Which accelerometers are present on device.
  39     bool has[ACCELEROMETER_SOURCE_COUNT];
  40
  41     // Scale of accelerometers (i.e. raw value * scale = m/s^2).
  42     float scale[ACCELEROMETER_SOURCE_COUNT][3];
  43
  44     // Index of each accelerometer axis in data stream.
  45     int index[ACCELEROMETER_SOURCE_COUNT][3];
  46   };
  47   typedef base::RefCountedData<ConfigurationData> Configuration;
  48   typedef base::RefCountedData<char[12]> Reading;
  49
  50   // An interface to receive data from the AccelerometerReader.
  51   class Observer {
  52    public:
  53     virtual void OnAccelerometerUpdated(const AccelerometerUpdate& update) = 0;
  54
  55    protected:
  56     virtual ~Observer() {}
  57   };
  58
  59   static AccelerometerReader* GetInstance();
  60
  61   void Initialize(scoped_refptr<base::TaskRunner> blocking_task_runner);
  62
  63   // Add/Remove observers.
  64   void AddObserver(Observer* observer);
  65   void RemoveObserver(Observer* observer);
  66
  67  protected:
  68   AccelerometerReader();
  69   virtual ~AccelerometerReader();
  70
  71  private:
  72   friend struct DefaultSingletonTraits<AccelerometerReader>;
  73
  74   // Dispatched when initialization is complete. If |success|, |configuration|
  75   // provides the details of the detected accelerometer.
  76   void OnInitialized(scoped_refptr<Configuration> configuration, bool success);
  77
  78   // Triggers an asynchronous read from the accelerometer, signalling
  79   // OnDataRead with the result.
  80   void TriggerRead();
  81
  82   // If |success|, converts the raw reading to an AccelerometerUpdate
  83   // message and notifies the |delegate_| with the new readings.
  84   // Triggers another read from the accelerometer at the current sampling rate.
  85   void OnDataRead(scoped_refptr<Reading> reading, bool success);
  86
  87   // The task runner to use for blocking tasks.
  88   scoped_refptr<base::TaskRunner> task_runner_;
  89
  90   // The last seen accelerometer data.
  91   AccelerometerUpdate update_;
  92
  93   // The accelerometer configuration.
  94   scoped_refptr<Configuration> configuration_;
  95
  96   ObserverList<Observer, true> observers_;
  97
  98   base::WeakPtrFactory<AccelerometerReader> weak_factory_;
  99
 100   DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
 101 };
 102
 103 }  // namespace chromeos
 104
 105 #endif  // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_