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 <vector>
   9
  10 #include "base/memory/ref_counted.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "base/observer_list.h"
  13 #include "chromeos/chromeos_export.h"
  14 #include "ui/accelerometer/accelerometer_types.h"
  15
  16 namespace base {
  17 class TaskRunner;
  18 }
  19
  20 namespace chromeos {
  21
  22 // Reads an accelerometer device and reports data back to an
  23 // AccelerometerDelegate.
  24 class CHROMEOS_EXPORT AccelerometerReader {
  25  public:
  26   // Configuration structure for accelerometer device.
  27   struct ConfigurationData {
  28     ConfigurationData();
  29     ~ConfigurationData();
  30
  31     // Scale of accelerometers (i.e. raw value * 1.0f / scale = G's).
  32     unsigned int base_scale;
  33     unsigned int lid_scale;
  34
  35     // Index of each accelerometer axis in data stream.
  36     std::vector<unsigned int> index;
  37   };
  38   typedef base::RefCountedData<ConfigurationData> Configuration;
  39   typedef base::RefCountedData<char[12]> Reading;
  40
  41   // An interface to receive data from the AccelerometerReader.
  42   class Delegate {
  43    public:
  44     virtual void HandleAccelerometerUpdate(
  45         const ui::AccelerometerUpdate& update) = 0;
  46   };
  47
  48   AccelerometerReader(base::TaskRunner* blocking_task_runner,
  49                       Delegate* delegate);
  50   ~AccelerometerReader();
  51
  52  private:
  53   // Dispatched when initialization is complete. If |success|, |configuration|
  54   // provides the details of the detected accelerometer.
  55   void OnInitialized(scoped_refptr<Configuration> configuration, bool success);
  56
  57   // Triggers an asynchronous read from the accelerometer, signalling
  58   // OnDataRead with the result.
  59   void TriggerRead();
  60
  61   // If |success|, converts the raw reading to an AccelerometerUpdate
  62   // message and notifies the |delegate_| with the new readings.
  63   // Triggers another read from the accelerometer at the current sampling rate.
  64   void OnDataRead(scoped_refptr<Reading> reading, bool success);
  65
  66   // The task runner to use for blocking tasks.
  67   scoped_refptr<base::TaskRunner> task_runner_;
  68
  69   // A weak pointer to the delegate to send accelerometer readings to.
  70   Delegate* delegate_;
  71
  72   // The last seen accelerometer data.
  73   ui::AccelerometerUpdate update_;
  74
  75   // The accelerometer configuration.
  76   scoped_refptr<Configuration> configuration_;
  77
  78   base::WeakPtrFactory<AccelerometerReader> weak_factory_;
  79
  80   DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
  81 };
  82
  83 }  // namespace chromeos
  84
  85 #endif  // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_