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      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/gfx/geometry/vector3d_f.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 HandleAccelerometerReading(const gfx::Vector3dF& base,
     45                                             const gfx::Vector3dF& lid) = 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 a pair of Vector3dF
     62   // values 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 accelerometer configuration.
     73   scoped_refptr<Configuration> configuration_;
     74 
     75   base::WeakPtrFactory<AccelerometerReader> weak_factory_;
     76 
     77   DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
     78 };
     79 
     80 }  // namespace chromeos
     81 
     82 #endif  // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
     83