Read and expose accelerometer values from cros-ec-accel trigger.

chromeos/accelerometer/accelerometer_reader.h

+// 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 <vector>
+
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
+#include "chromeos/chromeos_export.h"
+#include "ui/gfx/geometry/vector3d_f.h"
+
+namespace chromeos {
+
+// Reads an accelerometer device and reports data back to an
+// AccelerometerDelegate.
+class CHROMEOS_EXPORT AccelerometerReader {
+ public:
+  // An interface to receive data from the AccelerometerReader.
+  class Delegate {
+   public:
+    virtual void HandleAccelerometerReading(const gfx::Vector3dF& base,
+                                            const gfx::Vector3dF& lid) = 0;
+  };
+
+  explicit AccelerometerReader(Delegate* delegate);
+  ~AccelerometerReader();
+
+ private:
+  // Detects and reads configuration of the accelerometer device.
+  void Initialize();
+
+  // Dispatched when initialization is complete. |has_accelerometer_| is true if
+  // an accelerometer was detected and all configuration parameters read.
+  void OnInitialized();
+
+  // Triggers an asynchronous read from the accelerometer, signalling
+  // OnDataRead with |read_sucess_| set to true if the read was successful.
+  void TriggerRead();
+
+  // Triggers the accelerometer and reads the sampled values. Sets
+  // |read_success_| to true and |base_reading_| and |lid_reading_| to the
+  // read values if successful.
+  void ReadAccelerometer();
+
+  // If |read_success_|, notifies the |delegate_| with the new readings.
+  // Triggers another read from the accelerometer at the current sampling rate.
+  void OnDataRead();
+
+  // A weak pointer to the delegate to send accelerometer readings to.
+  Delegate* delegate_;
+
+  // True after Initialize has run if an accelerometer sensor exists.
+  bool has_accelerometer_;
+
+  // The index of each axis of each accelerometer.
+  std::vector<unsigned int> accelerometer_index_;
+
+  // The scale of the base and lid accelerometers.
+  unsigned int accelerometer_base_scale_;
+  unsigned int accelerometer_lid_scale_;
+
+  // Set to false before triggering a read. If the read is successful, set to
+  // true by ReadAccelerometer.
+  bool read_success_;
+
+  // The last readings from the base and lid accelerometers. DO NOT directly
+  // read these as they are updated from the blocking thread pool. Instead,
+  // only use the values as passed to the |delegate_|.
+  // TODO(flackr): Pass the values back from the blocking thread pool to avoid
+  // the potential for them to be read while they're being updated.
+  gfx::Vector3dF base_reading_;
+  gfx::Vector3dF lid_reading_;
+
+  base::WeakPtrFactory<AccelerometerReader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccelerometerReader);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_