Implement DeviceMotionEvent API

content/browser/device_sensors/sensor_manager_chromeos.cc

 // Copyright 2015 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.
 
 #include "content/browser/device_sensors/sensor_manager_chromeos.h"
 
 #include <math.h>
 
-#include "base/logging.h"
 #include "chromeos/accelerometer/accelerometer_reader.h"
 #include "chromeos/accelerometer/accelerometer_types.h"
+#include "content/browser/device_sensors/inertial_sensor_consts.h"
 #include "ui/gfx/geometry/vector3d_f.h"
 
 namespace {
 // Conversion ratio from radians to degrees.
 const double kRad2deg = 180.0 / M_PI;
 }
 
 namespace content {
 
-SensorManagerChromeOS::SensorManagerChromeOS() : orientation_buffer_(nullptr) {
+SensorManagerChromeOS::SensorManagerChromeOS()
+    : motion_buffer_(nullptr), orientation_buffer_(nullptr) {
 }
 
 SensorManagerChromeOS::~SensorManagerChromeOS() {
 }
 
-bool SensorManagerChromeOS::StartFetchingDeviceOrientationData(
-    DeviceOrientationHardwareBuffer* buffer) {
-  DCHECK(buffer);
-  {
-    base::AutoLock autolock(orientation_buffer_lock_);
-    if (orientation_buffer_)
-      return false;
-    orientation_buffer_ = buffer;
+void SensorManagerChromeOS::StartFetchingDeviceMotionData(
+    DeviceMotionHardwareBuffer* buffer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!motion_buffer_);
+  motion_buffer_ = buffer;
 
-    // No compass information, so we cannot provide absolute orientation.
-    orientation_buffer_->seqlock.WriteBegin();
-    orientation_buffer_->data.absolute = false;
-    orientation_buffer_->data.hasAbsolute = true;
-    orientation_buffer_->seqlock.WriteEnd();
-  }
+  motion_buffer_->seqlock.WriteBegin();
+  // The interval between updates is the longer of the rate set on the buffer,
+  // and the rate at which AccelerometerReader polls the sensor.
+  motion_buffer_->data.interval = std::max(
+      kInertialSensorIntervalMicroseconds / 1000,
+      chromeos::AccelerometerReader::kDelayBetweenReadsMs);
+  motion_buffer_->seqlock.WriteEnd();
 
   StartObservingAccelerometer();
+}
+
+bool SensorManagerChromeOS::StopFetchingDeviceMotionData() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!motion_buffer_)
+    return false;
+
+  // Make sure to indicate that the sensor data is no longer available.
+  motion_buffer_->seqlock.WriteBegin();
+  motion_buffer_->data.allAvailableSensorsAreActive = false;
+  motion_buffer_->seqlock.WriteEnd();
+
+  motion_buffer_ = nullptr;
+
+  if (!orientation_buffer_)
+    StopObservingAccelerometer();
   return true;
 }
 
+void SensorManagerChromeOS::StartFetchingDeviceOrientationData(
+    DeviceOrientationHardwareBuffer* buffer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!orientation_buffer_);
+  orientation_buffer_ = buffer;
+
+  // No compass information, so we cannot provide absolute orientation.
+  orientation_buffer_->seqlock.WriteBegin();
+  orientation_buffer_->data.absolute = false;
+  orientation_buffer_->data.hasAbsolute = true;
+  orientation_buffer_->seqlock.WriteEnd();
+
+  StartObservingAccelerometer();
+}
+
 bool SensorManagerChromeOS::StopFetchingDeviceOrientationData() {
-  {
-    base::AutoLock autolock(orientation_buffer_lock_);
-    if (!orientation_buffer_)
-      return false;
-    // Make sure to indicate that the sensor data is no longer available.
-    orientation_buffer_->seqlock.WriteBegin();
-    orientation_buffer_->data.allAvailableSensorsAreActive = false;
-    orientation_buffer_->seqlock.WriteEnd();
-    orientation_buffer_ = nullptr;
-  }
+  DCHECK(thread_checker_.CalledOnValidThread());
+  if (!orientation_buffer_)
+    return false;
+  // Make sure to indicate that the sensor data is no longer available.
+  orientation_buffer_->seqlock.WriteBegin();
+  orientation_buffer_->data.allAvailableSensorsAreActive = false;
+  orientation_buffer_->seqlock.WriteEnd();
+  orientation_buffer_ = nullptr;
 
-  StopObservingAccelerometer();
+  if (!motion_buffer_)
+    StopObservingAccelerometer();
   return true;
 }
 
 void SensorManagerChromeOS::OnAccelerometerUpdated(
-    const chromeos::AccelerometerUpdate& update) {
-  base::AutoLock autolock(orientation_buffer_lock_);
+    scoped_refptr<const chromeos::AccelerometerUpdate> update) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  chromeos::AccelerometerSource source;
+  if (update->has(chromeos::ACCELEROMETER_SOURCE_SCREEN))
+    source = chromeos::ACCELEROMETER_SOURCE_SCREEN;
+  else if (update->has(chromeos::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD))
+    source = chromeos::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD;
+  else
+    return;
+
+  double x = update->get(source).x;
+  double y = update->get(source).y;
+  double z = update->get(source).z;
+
+  GenerateMotionEvent(x, y, z);
+  GenerateOrientationEvent(x, y, z);
+}
+
+void SensorManagerChromeOS::StartObservingAccelerometer() {
+  if (chromeos::AccelerometerReader::GetInstance()->HasObserver(this))
+    return;
+  chromeos::AccelerometerReader::GetInstance()->AddObserver(this);

[Nico, 2015/03/11 14:17:06]

This is the only place I can see where this AddObserver() method is called.
Can't you just keep the "added_observer_" state locally?

[jonross, 2015/03/11 17:52:48]

I've removed the HasObserver methods.

To update here I've added checks at the call sites. Becoming an observer will
only happen when no previous buffer exists. (Instead of an extra flag)

+}
+
+void SensorManagerChromeOS::StopObservingAccelerometer() {
+  DCHECK(chromeos::AccelerometerReader::GetInstance()->HasObserver(this));
+  chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
+}
+
+void SensorManagerChromeOS::GenerateMotionEvent(double x, double y, double z) {
+  if (!motion_buffer_)
+    return;
+
+  motion_buffer_->seqlock.WriteBegin();
+  motion_buffer_->data.accelerationIncludingGravityX = x;
+  motion_buffer_->data.hasAccelerationIncludingGravityX = true;
+  motion_buffer_->data.accelerationIncludingGravityY = y;
+  motion_buffer_->data.hasAccelerationIncludingGravityY = true;
+  motion_buffer_->data.accelerationIncludingGravityZ = z;
+  motion_buffer_->data.hasAccelerationIncludingGravityZ = true;
+  motion_buffer_->data.allAvailableSensorsAreActive = true;
+  motion_buffer_->seqlock.WriteEnd();
+}
+
+void SensorManagerChromeOS::GenerateOrientationEvent(double x,
+                                                     double y,
+                                                     double z) {
   if (!orientation_buffer_)
     return;
 
-  chromeos::AccelerometerSource source;
-  if (update.has(chromeos::ACCELEROMETER_SOURCE_SCREEN)) {
-    source = chromeos::ACCELEROMETER_SOURCE_SCREEN;
-  } else if (update.has(chromeos::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD)) {
-    source = chromeos::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD;
-  } else {
-    return;
-  }
-
-  double x = update.get(source).x;
-  double y = update.get(source).y;
-  double z = update.get(source).z;
-
   // Create a unit vector for trigonometry
   // TODO(jonross): Stop reversing signs for vector components once
   // accelerometer values have been fixed. crbug.com/431391
   // Ternaries are to remove -0.0f which gives incorrect trigonometrical
   // results.
   gfx::Vector3dF data(x, y ? -y : 0.0f, z ? -z : 0.0f);
   data.Scale(1.0f / data.Length());
 
   // Transform accelerometer to W3C angles, using the Z-X-Y Eulerangles matrix.
   // x = sin(gamma)
@@ skipping 11 matching lines @@
     gamma = -90.0f;
   orientation_buffer_->seqlock.WriteBegin();
   orientation_buffer_->data.beta = beta;
   orientation_buffer_->data.hasBeta = true;
   orientation_buffer_->data.gamma = gamma;
   orientation_buffer_->data.hasGamma = true;
   orientation_buffer_->data.allAvailableSensorsAreActive = true;
   orientation_buffer_->seqlock.WriteEnd();
 }
 
-void SensorManagerChromeOS::StartObservingAccelerometer() {
-  chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
-}
-
-void SensorManagerChromeOS::StopObservingAccelerometer() {
-  chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
-}
-
 }  // namespace content