content/browser/device_sensors/data_fetcher_shared_memory_mac.cc

   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 #include "data_fetcher_shared_memory.h"
   6
   7 #include "base/logging.h"
   8 #include "base/metrics/histogram.h"
   9 #include "third_party/sudden_motion_sensor/sudden_motion_sensor_mac.h"
  10
  11 namespace {
  12
  13 const double kMeanGravity = 9.80665;
  14
  15 void FetchMotion(SuddenMotionSensor* sensor,
  16     content::DeviceMotionHardwareBuffer* buffer) {
  17   DCHECK(buffer);
  18
  19   float axis_value[3];
  20   if (!sensor->ReadSensorValues(axis_value))
  21     return;
  22
  23   buffer->seqlock.WriteBegin();
  24   buffer->data.accelerationIncludingGravityX = axis_value[0] * kMeanGravity;
  25   buffer->data.hasAccelerationIncludingGravityX = true;
  26   buffer->data.accelerationIncludingGravityY = axis_value[1] * kMeanGravity;
  27   buffer->data.hasAccelerationIncludingGravityY = true;
  28   buffer->data.accelerationIncludingGravityZ = axis_value[2] * kMeanGravity;
  29   buffer->data.hasAccelerationIncludingGravityZ = true;
  30   buffer->data.allAvailableSensorsAreActive = true;
  31   buffer->seqlock.WriteEnd();
  32 }
  33
  34 void FetchOrientation(SuddenMotionSensor* sensor,
  35     content::DeviceOrientationHardwareBuffer* buffer) {
  36   DCHECK(buffer);
  37
  38   // Retrieve per-axis calibrated values.
  39   float axis_value[3];
  40   if (!sensor->ReadSensorValues(axis_value))
  41     return;
  42
  43   // Transform the accelerometer values to W3C draft angles.
  44   //
  45   // Accelerometer values are just dot products of the sensor axes
  46   // by the gravity vector 'g' with the result for the z axis inverted.
  47   //
  48   // To understand this transformation calculate the 3rd row of the z-x-y
  49   // Euler angles rotation matrix (because of the 'g' vector, only 3rd row
  50   // affects to the result). Note that z-x-y matrix means R = Ry * Rx * Rz.
  51   // Then, assume alpha = 0 and you get this:
  52   //
  53   // x_acc = sin(gamma)
  54   // y_acc = - cos(gamma) * sin(beta)
  55   // z_acc = cos(beta) * cos(gamma)
  56   //
  57   // After that the rest is just a bit of trigonometry.
  58   //
  59   // Also note that alpha can't be provided but it's assumed to be always zero.
  60   // This is necessary in order to provide enough information to solve
  61   // the equations.
  62   //
  63   const double kRad2deg = 180.0 / M_PI;
  64   double beta = kRad2deg * atan2(-axis_value[1], axis_value[2]);
  65   double gamma = kRad2deg * asin(axis_value[0]);
  66
  67   // Make sure that the interval boundaries comply with the specification. At
  68   // this point, beta is [-180, 180] and gamma is [-90, 90], but the spec has
  69   // the upper bound open on both.
  70   if (beta == 180.0)
  71     beta = -180;  // -180 == 180 (upside-down)
  72   if (gamma == 90.0)
  73     gamma = nextafter(90, 0);
  74
  75   // At this point, DCHECKing is paranoia. Never hurts.
  76   DCHECK_GE(beta, -180.0);
  77   DCHECK_LT(beta,  180.0);
  78   DCHECK_GE(gamma, -90.0);
  79   DCHECK_LT(gamma,  90.0);
  80
  81   buffer->seqlock.WriteBegin();
  82   buffer->data.beta = beta;
  83   buffer->data.hasBeta = true;
  84   buffer->data.gamma = gamma;
  85   buffer->data.hasGamma = true;
  86   buffer->data.allAvailableSensorsAreActive = true;
  87   buffer->seqlock.WriteEnd();
  88 }
  89
  90 }  // namespace
  91
  92 namespace content {
  93
  94 DataFetcherSharedMemory::DataFetcherSharedMemory() {
  95 }
  96
  97 DataFetcherSharedMemory::~DataFetcherSharedMemory() {
  98 }
  99
 100 void DataFetcherSharedMemory::Fetch(unsigned consumer_bitmask) {
 101   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 102   DCHECK(sudden_motion_sensor_);
 103   DCHECK(consumer_bitmask & CONSUMER_TYPE_ORIENTATION ||
 104          consumer_bitmask & CONSUMER_TYPE_MOTION);
 105
 106   if (consumer_bitmask & CONSUMER_TYPE_ORIENTATION)
 107     FetchOrientation(sudden_motion_sensor_.get(), orientation_buffer_);
 108   if (consumer_bitmask & CONSUMER_TYPE_MOTION)
 109     FetchMotion(sudden_motion_sensor_.get(), motion_buffer_);
 110 }
 111
 112 DataFetcherSharedMemory::FetcherType DataFetcherSharedMemory::GetType() const {
 113   return FETCHER_TYPE_POLLING_CALLBACK;
 114 }
 115
 116 bool DataFetcherSharedMemory::Start(ConsumerType consumer_type, void* buffer) {
 117   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 118   DCHECK(buffer);
 119
 120   if (!sudden_motion_sensor_)
 121     sudden_motion_sensor_.reset(SuddenMotionSensor::Create());
 122   bool sudden_motion_sensor_available = sudden_motion_sensor_.get() != NULL;
 123
 124   switch (consumer_type) {
 125     case CONSUMER_TYPE_MOTION:
 126       motion_buffer_ = static_cast<DeviceMotionHardwareBuffer*>(buffer);
 127       UMA_HISTOGRAM_BOOLEAN("InertialSensor.MotionMacAvailable",
 128           sudden_motion_sensor_available);
 129       if (!sudden_motion_sensor_available) {
 130         // No motion sensor available, fire an all-null event.
 131         motion_buffer_->seqlock.WriteBegin();
 132         motion_buffer_->data.allAvailableSensorsAreActive = true;
 133         motion_buffer_->seqlock.WriteEnd();
 134       }
 135       return sudden_motion_sensor_available;
 136     case CONSUMER_TYPE_ORIENTATION:
 137       orientation_buffer_ =
 138           static_cast<DeviceOrientationHardwareBuffer*>(buffer);
 139       UMA_HISTOGRAM_BOOLEAN("InertialSensor.OrientationMacAvailable",
 140           sudden_motion_sensor_available);
 141       if (sudden_motion_sensor_available) {
 142         // On Mac we cannot provide absolute orientation.
 143         orientation_buffer_->seqlock.WriteBegin();
 144         orientation_buffer_->data.absolute = false;
 145         orientation_buffer_->data.hasAbsolute = true;
 146         orientation_buffer_->seqlock.WriteEnd();
 147       } else {
 148         // No motion sensor available, fire an all-null event.
 149         orientation_buffer_->seqlock.WriteBegin();
 150         orientation_buffer_->data.allAvailableSensorsAreActive = true;
 151         orientation_buffer_->seqlock.WriteEnd();
 152       }
 153       return sudden_motion_sensor_available;
 154     default:
 155       NOTREACHED();
 156   }
 157   return false;
 158 }
 159
 160 bool DataFetcherSharedMemory::Stop(ConsumerType consumer_type) {
 161   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 162
 163   switch (consumer_type) {
 164     case CONSUMER_TYPE_MOTION:
 165       if (motion_buffer_) {
 166         motion_buffer_->seqlock.WriteBegin();
 167         motion_buffer_->data.allAvailableSensorsAreActive = false;
 168         motion_buffer_->seqlock.WriteEnd();
 169         motion_buffer_ = NULL;
 170       }
 171       return true;
 172     case CONSUMER_TYPE_ORIENTATION:
 173       if (orientation_buffer_) {
 174         orientation_buffer_->seqlock.WriteBegin();
 175         orientation_buffer_->data.allAvailableSensorsAreActive = false;
 176         orientation_buffer_->seqlock.WriteEnd();
 177         orientation_buffer_ = NULL;
 178       }
 179       return true;
 180     default:
 181       NOTREACHED();
 182   }
 183   return false;
 184 }
 185
 186 }  // namespace content