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