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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
#define CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list_threadsafe.h"
#include "chromeos/accelerometer/accelerometer_types.h"
#include "chromeos/chromeos_export.h"
template <typename T>
struct DefaultSingletonTraits;
namespace base {
class TaskRunner;
}
namespace chromeos {
// Reads an accelerometer device and reports data back to an
// AccelerometerDelegate.
class CHROMEOS_EXPORT AccelerometerReader {
public:
// The time to wait between reading the accelerometer.
static const int kDelayBetweenReadsMs;
// Configuration structure for accelerometer device.
struct ConfigurationData {
ConfigurationData();
~ConfigurationData();
// Number of accelerometers on device.
size_t count;
// Length of accelerometer updates.
size_t length;
// Which accelerometers are present on device.
bool has[ACCELEROMETER_SOURCE_COUNT];
// Scale of accelerometers (i.e. raw value * scale = m/s^2).
float scale[ACCELEROMETER_SOURCE_COUNT][3];
// Index of each accelerometer axis in data stream.
int index[ACCELEROMETER_SOURCE_COUNT][3];
};
typedef base::RefCountedData<ConfigurationData> Configuration;
typedef base::RefCountedData<char[12]> Reading;
// An interface to receive data from the AccelerometerReader.
class Observer {
public:
virtual void OnAccelerometerUpdated(
scoped_refptr<const AccelerometerUpdate> update) = 0;
protected:
virtual ~Observer() {}
};
static AccelerometerReader* GetInstance();
void Initialize(scoped_refptr<base::TaskRunner> blocking_task_runner);
// Add/Remove observers.
void AddObserver(Observer* observer);
void RemoveObserver(Observer* observer);
protected:
AccelerometerReader();
virtual ~AccelerometerReader();
private:
friend struct DefaultSingletonTraits<AccelerometerReader>;
// Dispatched when initialization is complete. If |success|, |configuration|
// provides the details of the detected accelerometer.
void OnInitialized(scoped_refptr<Configuration> configuration, bool success);
// Triggers an asynchronous read from the accelerometer, signalling
// OnDataRead with the result.
void TriggerRead();
// If |success|, converts the raw reading to an AccelerometerUpdate
// message and notifies the |delegate_| with the new readings.
// Triggers another read from the accelerometer at the current sampling rate.
void OnDataRead(scoped_refptr<Reading> reading, bool success);
// The task runner to use for blocking tasks.
scoped_refptr<base::TaskRunner> task_runner_;
// The last seen accelerometer data.
scoped_refptr<AccelerometerUpdate> update_;
// The accelerometer configuration.
scoped_refptr<Configuration> configuration_;
scoped_refptr<ObserverListThreadSafe<Observer>> observers_;
base::WeakPtrFactory<AccelerometerReader> weak_factory_;
DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
};
} // namespace chromeos
#endif // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
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