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) {
+void SensorManagerChromeOS::StartFetchingDeviceMotionData(
+    DeviceMotionHardwareBuffer* buffer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(buffer);

[flackr, 2015/03/10 17:21:11]

nit: This is probably an unnecessary check, since the buffer is used immediately
within this method the browser will crash on line 35 if buffer is NULL anyways.

[jonross, 2015/03/10 18:16:10]

Looking into the call path it isn't needed. There is an earlier check that I
didn't noticed:

https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/de...

-  {
-    base::AutoLock autolock(orientation_buffer_lock_);
-    if (orientation_buffer_)
-      return false;
-    orientation_buffer_ = buffer;
+  CHECK(!motion_buffer_);

[timvolodine, 2015/03/10 17:31:33]

I wouldn't use CHECK here, seems a bit drastic to crash the whole browser
because of this. Think DCHECK is probably sufficient. Also not sure if
motion_buffer_ can actually be not null in very special cases, like crash of a
renderer..

[jonross, 2015/03/10 18:16:10]

Changed to DCHECK. That would be a rare case if renderer crashed and no stop
message was sent. However the shared memory buffers are created and tracked from
within content: 

https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/de...

So it could be safe to continue to use a non-null 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(buffer);

[flackr, 2015/03/10 17:21:11]

ditto

[jonross, 2015/03/10 18:16:09]

Done.

+  CHECK(!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);
+}
+
+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