content/browser/device_orientation/data_fetcher_shared_memory_mac.cc

   1 // Copyright 2013 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   // TODO(aousterh): should absolute_ be set to false here?
  68   // See crbug.com/136010.
  69
  70   // Make sure that the interval boundaries comply with the specification. At
  71   // this point, beta is [-180, 180] and gamma is [-90, 90], but the spec has
  72   // the upper bound open on both.
  73   if (beta == 180.0)
  74     beta = -180;  // -180 == 180 (upside-down)
  75   if (gamma == 90.0)
  76     gamma = nextafter(90, 0);
  77
  78   // At this point, DCHECKing is paranoia. Never hurts.
  79   DCHECK_GE(beta, -180.0);
  80   DCHECK_LT(beta,  180.0);
  81   DCHECK_GE(gamma, -90.0);
  82   DCHECK_LT(gamma,  90.0);
  83
  84   buffer->seqlock.WriteBegin();
  85   buffer->data.beta = beta;
  86   buffer->data.hasBeta = true;
  87   buffer->data.gamma = gamma;
  88   buffer->data.hasGamma = true;
  89   buffer->data.allAvailableSensorsAreActive = true;
  90   buffer->seqlock.WriteEnd();
  91 }
  92
  93 }  // namespace
  94
  95 namespace content {
  96
  97 DataFetcherSharedMemory::DataFetcherSharedMemory() {
  98 }
  99
 100 DataFetcherSharedMemory::~DataFetcherSharedMemory() {
 101 }
 102
 103 void DataFetcherSharedMemory::Fetch(unsigned consumer_bitmask) {
 104   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 105   DCHECK(sudden_motion_sensor_);
 106   DCHECK(consumer_bitmask & CONSUMER_TYPE_ORIENTATION ||
 107          consumer_bitmask & CONSUMER_TYPE_MOTION);
 108
 109   if (consumer_bitmask & CONSUMER_TYPE_ORIENTATION)
 110     FetchOrientation(sudden_motion_sensor_.get(), orientation_buffer_);
 111   if (consumer_bitmask & CONSUMER_TYPE_MOTION)
 112     FetchMotion(sudden_motion_sensor_.get(), motion_buffer_);
 113 }
 114
 115 DataFetcherSharedMemory::FetcherType DataFetcherSharedMemory::GetType() const {
 116   return FETCHER_TYPE_POLLING_CALLBACK;
 117 }
 118
 119 bool DataFetcherSharedMemory::Start(ConsumerType consumer_type, void* buffer) {
 120   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 121   DCHECK(buffer);
 122
 123   switch (consumer_type) {
 124     case CONSUMER_TYPE_MOTION:
 125       motion_buffer_ = static_cast<DeviceMotionHardwareBuffer*>(buffer);
 126       if (!sudden_motion_sensor_)
 127         sudden_motion_sensor_.reset(SuddenMotionSensor::Create());
 128       UMA_HISTOGRAM_BOOLEAN("InertialSensor.MotionMacAvailable",
 129           sudden_motion_sensor_.get() != NULL);
 130       return sudden_motion_sensor_.get() != NULL;
 131     case CONSUMER_TYPE_ORIENTATION:
 132       orientation_buffer_ =
 133           static_cast<DeviceOrientationHardwareBuffer*>(buffer);
 134       if (!sudden_motion_sensor_)
 135         sudden_motion_sensor_.reset(SuddenMotionSensor::Create());
 136       UMA_HISTOGRAM_BOOLEAN("InertialSensor.OrientationMacAvailable",
 137           sudden_motion_sensor_.get() != NULL);
 138       return sudden_motion_sensor_.get() != NULL;
 139     default:
 140       NOTREACHED();
 141   }
 142   return false;
 143 }
 144
 145 bool DataFetcherSharedMemory::Stop(ConsumerType consumer_type) {
 146   DCHECK(base::MessageLoop::current() == GetPollingMessageLoop());
 147
 148   switch (consumer_type) {
 149     case CONSUMER_TYPE_MOTION:
 150       if (motion_buffer_) {
 151         motion_buffer_->seqlock.WriteBegin();
 152         motion_buffer_->data.allAvailableSensorsAreActive = false;
 153         motion_buffer_->seqlock.WriteEnd();
 154         motion_buffer_ = NULL;
 155       }
 156       return true;
 157     case CONSUMER_TYPE_ORIENTATION:
 158       if (orientation_buffer_) {
 159         orientation_buffer_->seqlock.WriteBegin();
 160         orientation_buffer_->data.allAvailableSensorsAreActive = false;
 161         orientation_buffer_->seqlock.WriteEnd();
 162         orientation_buffer_ = NULL;
 163       }
 164       return true;
 165     default:
 166       NOTREACHED();
 167   }
 168   return false;
 169 }
 170
 171 }  // namespace content