content/browser/device_sensors/sensor_manager_chromeos.cc

   1 // Copyright 2015 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 #include "content/browser/device_sensors/sensor_manager_chromeos.h"
   6
   7 #include <math.h>
   8
   9 #include "base/logging.h"
  10 #include "chromeos/accelerometer/accelerometer_reader.h"
  11 #include "chromeos/accelerometer/accelerometer_types.h"
  12 #include "ui/gfx/geometry/vector3d_f.h"
  13
  14 namespace {
  15 // Conversion ratio from radians to degrees.
  16 const double kRad2deg = 180.0 / M_PI;
  17 }
  18
  19 namespace content {
  20
  21 SensorManagerChromeOS::SensorManagerChromeOS() : orientation_buffer_(nullptr) {
  22 }
  23
  24 SensorManagerChromeOS::~SensorManagerChromeOS() {
  25 }
  26
  27 bool SensorManagerChromeOS::StartFetchingDeviceOrientationData(
  28     DeviceOrientationHardwareBuffer* buffer) {
  29   DCHECK(buffer);
  30   {
  31     base::AutoLock autolock(orientation_buffer_lock_);
  32     if (orientation_buffer_)
  33       return false;
  34     orientation_buffer_ = buffer;
  35
  36     // No compass information, so we cannot provide absolute orientation.
  37     orientation_buffer_->seqlock.WriteBegin();
  38     orientation_buffer_->data.absolute = false;
  39     orientation_buffer_->data.hasAbsolute = true;
  40     orientation_buffer_->seqlock.WriteEnd();
  41   }
  42
  43   StartObservingAccelerometer();
  44   return true;
  45 }
  46
  47 bool SensorManagerChromeOS::StopFetchingDeviceOrientationData() {
  48   {
  49     base::AutoLock autolock(orientation_buffer_lock_);
  50     if (!orientation_buffer_)
  51       return false;
  52     // Make sure to indicate that the sensor data is no longer available.
  53     orientation_buffer_->seqlock.WriteBegin();
  54     orientation_buffer_->data.allAvailableSensorsAreActive = false;
  55     orientation_buffer_->seqlock.WriteEnd();
  56     orientation_buffer_ = nullptr;
  57   }
  58
  59   StopObservingAccelerometer();
  60   return true;
  61 }
  62
  63 void SensorManagerChromeOS::OnAccelerometerUpdated(
  64     const chromeos::AccelerometerUpdate& update) {
  65   base::AutoLock autolock(orientation_buffer_lock_);
  66   if (!orientation_buffer_)
  67     return;
  68
  69   chromeos::AccelerometerSource source;
  70   if (update.has(chromeos::ACCELEROMETER_SOURCE_SCREEN)) {
  71     source = chromeos::ACCELEROMETER_SOURCE_SCREEN;
  72   } else if (update.has(chromeos::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD)) {
  73     source = chromeos::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD;
  74   } else {
  75     return;
  76   }
  77
  78   double x = update.get(source).x;
  79   double y = update.get(source).y;
  80   double z = update.get(source).z;
  81
  82   // Create a unit vector for trigonometry
  83   // TODO(jonross): Stop reversing signs for vector components once
  84   // accelerometer values have been fixed. crbug.com/431391
  85   // Ternaries are to remove -0.0f which gives incorrect trigonometrical
  86   // results.
  87   gfx::Vector3dF data(x, y ? -y : 0.0f, z ? -z : 0.0f);
  88   data.Scale(1.0f / data.Length());
  89
  90   // Transform accelerometer to W3C angles, using the Z-X-Y Eulerangles matrix.
  91   // x = sin(gamma)
  92   // y = -cos(gamma) * sin(beta)
  93   // z = cos(beta) * cos(gamma)
  94   // With only accelerometer alpha cannot be provided.
  95   double beta = kRad2deg * atan2(data.y(), data.z());
  96   double gamma = kRad2deg * asin(data.x());
  97
  98   // Convert beta and gamma to fit the intervals in the specification. Beta is
  99   // [-180, 180) and gamma is [-90, 90).
 100   if (beta >= 180.0f)
 101     beta = -180.0f;
 102   if (gamma >= 90.0f)
 103     gamma = -90.0f;
 104   orientation_buffer_->seqlock.WriteBegin();
 105   orientation_buffer_->data.beta = beta;
 106   orientation_buffer_->data.hasBeta = true;
 107   orientation_buffer_->data.gamma = gamma;
 108   orientation_buffer_->data.hasGamma = true;
 109   orientation_buffer_->data.allAvailableSensorsAreActive = true;
 110   orientation_buffer_->seqlock.WriteEnd();
 111 }
 112
 113 void SensorManagerChromeOS::StartObservingAccelerometer() {
 114   chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
 115 }
 116
 117 void SensorManagerChromeOS::StopObservingAccelerometer() {
 118   chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
 119 }
 120
 121 }  // namespace content