Implement java-side browser sensor polling for device motion and device orientation DOM events.

content/public/android/java/src/org/chromium/content/browser/DeviceMotionAndOrientation.java

-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright (c) 2013 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.
 
 package org.chromium.content.browser;
 
 import android.content.Context;
 import android.hardware.Sensor;
 import android.hardware.SensorEvent;
 import android.hardware.SensorEventListener;
 import android.hardware.SensorManager;
 import android.os.Handler;
 import android.os.Looper;
+import android.util.Log;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
 import org.chromium.base.WeakContext;
 
 import java.util.List;
+import java.util.Set;
 
 /**
- * Android implementation of the DeviceOrientation API.
+ * Android implementation of the device motion and orientation APIs.
  */
 @JNINamespace("content")
-class DeviceOrientation implements SensorEventListener {
+class DeviceMotionAndOrientation implements SensorEventListener {
+
+    private static final String LOGTAG = "DeviceMotionAndOrientation";
 
     // These fields are lazily initialized by getHandler().
     private Thread mThread;
     private Handler mHandler;
 
     // The lock to access the mHandler.
     private Object mHandlerLock = new Object();
 
     // Non-zero if and only if we're listening for events.
     // To avoid race conditions on the C++ side, access must be synchronized.
     private int mNativePtr;
 
     // The lock to access the mNativePtr.
     private Object mNativePtrLock = new Object();
 
     // The gravity vector expressed in the body frame.

[Peter Beverloo, 2013/03/13 16:18:57]

This should read "The acceleration vector including gravity expressed in the
body frame.".

[timvolodine, 2013/03/13 17:53:02]

Done.

-    private float[] mGravityVector;
+    private float[] mAccelerationVector;
 
     // The geomagnetic vector expressed in the body frame.
     private float[] mMagneticFieldVector;
 
     // Lazily initialized when registering for notifications.
     private SensorManager mSensorManager;
 
     // The only instance of that class and its associated lock.
-    private static DeviceOrientation sSingleton;
+    private static DeviceMotionAndOrientation sSingleton;
     private static Object sSingletonLock = new Object();
 
-    private DeviceOrientation() {
+    /**
+     * constants for using in JNI calls, also see
+     * content/browser/device_orientation/data_fetcher_impl_android.cc
+     */
+    private static final int DEVICE_ORIENTATION = 0;
+    private static final int DEVICE_MOTION = 1;
+
+    private static ImmutableSet<Integer> DEVICE_ORIENTATION_SENSORS = ImmutableSet.of(
+            Sensor.TYPE_ACCELEROMETER,
+            Sensor.TYPE_MAGNETIC_FIELD);
+
+    private static ImmutableSet<Integer> DEVICE_MOTION_SENSORS = ImmutableSet.of(
+            Sensor.TYPE_ACCELEROMETER,
+            Sensor.TYPE_LINEAR_ACCELERATION,
+            Sensor.TYPE_GYROSCOPE);
+
+    private Set<Integer> mActiveSensors = Sets.newHashSet();
+    private boolean mDeviceMotionIsActive = false;
+    private boolean mDeviceOrientationIsActive = false;
+
+    private DeviceMotionAndOrientation() {
     }
 
     /**
      * Start listening for sensor events. If this object is already listening
      * for events, the old callback is unregistered first.
      *
      * @param nativePtr Value to pass to nativeGotOrientation() for each event.
      * @param rateInMilliseconds Requested callback rate in milliseconds. The
      *            actual rate may be higher. Unwanted events should be ignored.
+     * @param eventType Type of event to listen to, can be either DEVICE_ORIENTATION or
+     *            DEVICE_MOTION.

[Peter Beverloo, 2013/03/13 16:18:57]

nit: 11-space ident?  What should this be aligned with?  Line 90 seems to do
this wrong as well.

[timvolodine, 2013/03/13 17:53:02]

aligned with last row for readability.

On 2013/03/13 16:18:57, Peter Beverloo wrote:

      * @return True on success.
      */
     @CalledByNative
-    public boolean start(int nativePtr, int rateInMilliseconds) {
+    public boolean start(int nativePtr, int eventType, int rateInMilliseconds) {
+        boolean success = false;
         synchronized (mNativePtrLock) {
-            stop();
-            if (registerForSensors(rateInMilliseconds)) {
+            switch (eventType) {
+                case DEVICE_ORIENTATION:
+                    success = registerSensors(DEVICE_ORIENTATION_SENSORS, rateInMilliseconds,
+                                                 true);

[Peter Beverloo, 2013/03/13 16:18:57]

nit: indent with eight spaces, so equal to the "=" character in line 101.

[timvolodine, 2013/03/13 17:53:02]

Done.

+                    break;
+                case DEVICE_MOTION:
+                    success = registerSensors(DEVICE_MOTION_SENSORS, rateInMilliseconds, false);
+                    break;
+                default:
+                    Log.e(LOGTAG, "Unknown event type: " + eventType);
+                    return false;
+            }
+            if (success) {
                 mNativePtr = nativePtr;
-                return true;
+                setActiveEventType(eventType, true);
             }
-            return false;
+            return success;
         }
     }
 
     /**
-     * Stop listening for sensor events. Always succeeds.
+     * Stop listening for particular sensor events. Always succeeds.
      *
-     * We strictly guarantee that nativeGotOrientation() will not be called
+     * @param eventType Type of event to listen to, can be either DEVICE_ORIENTATION or
+     *            DEVICE_MOTION.

[Peter Beverloo, 2013/03/13 16:18:57]

nit: 11 space indent?

[timvolodine, 2013/03/13 17:53:02]

aligned to last line
On 2013/03/13 16:18:57, Peter Beverloo wrote:

+     * We strictly guarantee that the corresponding native*() methods will not be called
      * after this method returns.
      */
     @CalledByNative
-    public void stop() {
+    public void stop(int eventType) {
+        Set<Integer> sensorsToRemainActive = Sets.newHashSet();
         synchronized (mNativePtrLock) {
-            if (mNativePtr != 0) {
-                mNativePtr = 0;
-                unregisterForSensors();
+            switch (eventType) {
+                case DEVICE_ORIENTATION:
+                    if (mDeviceMotionIsActive) {
+                        sensorsToRemainActive.addAll(DEVICE_MOTION_SENSORS);
+                    }
+                    break;
+                case DEVICE_MOTION:
+                    if (mDeviceOrientationIsActive) {
+                        sensorsToRemainActive.addAll(DEVICE_ORIENTATION_SENSORS);
+                    }
+                    break;
+                default:
+                    Log.e(LOGTAG, "Unknown event type: " + eventType);
+                    return;
             }
+
+            Set<Integer> sensorsToDeactivate = Sets.newHashSet(mActiveSensors);
+            sensorsToDeactivate.removeAll(sensorsToRemainActive);
+            unregisterSensors(sensorsToDeactivate);
+            mNativePtr = 0;
+            setActiveEventType(eventType, false);
         }
     }
 
     @Override
     public void onAccuracyChanged(Sensor sensor, int accuracy) {
         // Nothing
     }
 
     @Override
     public void onSensorChanged(SensorEvent event) {
         switch (event.sensor.getType()) {
             case Sensor.TYPE_ACCELEROMETER:
-                if (mGravityVector == null) {
-                    mGravityVector = new float[3];
+                if (mAccelerationVector == null) {
+                    mAccelerationVector = new float[3];
                 }
-                System.arraycopy(event.values, 0, mGravityVector, 0, mGravityVector.length);
+                System.arraycopy(event.values, 0, mAccelerationVector, 0,
+                                 mAccelerationVector.length);

[Peter Beverloo, 2013/03/13 16:18:57]

nit: 8 space indent, so with the first "r".

[timvolodine, 2013/03/13 17:53:02]

Done.

+                if (mDeviceMotionIsActive) {
+                    gotAccelerationIncludingGravity(mAccelerationVector[0], mAccelerationVector[1],
+                                                    mAccelerationVector[2]);

[Peter Beverloo, 2013/03/13 16:18:57]

nit: 8 space indent, so with the second "e".

[timvolodine, 2013/03/13 17:53:02]

Done.

+                }
                 break;
-
+            case Sensor.TYPE_LINEAR_ACCELERATION:
+                gotAcceleration(event.values[0], event.values[1], event.values[2]);

[Peter Beverloo, 2013/03/13 16:18:57]

Should we protect this with if(mDeviceMotionIsActive)?  Dito with line 178.  It
shouldn't hurt in either case.

[timvolodine, 2013/03/13 17:53:02]

Done.

+                break;
+            case Sensor.TYPE_GYROSCOPE:
+                gotRotationRate(event.values[0], event.values[1], event.values[2]);
+                break;
             case Sensor.TYPE_MAGNETIC_FIELD:
                 if (mMagneticFieldVector == null) {
                     mMagneticFieldVector = new float[3];
                 }
                 System.arraycopy(event.values, 0, mMagneticFieldVector, 0,
                                  mMagneticFieldVector.length);
                 break;
-
             default:
                 // Unexpected
                 return;
         }
 
-        getOrientationUsingGetRotationMatrix();
+        if (mDeviceOrientationIsActive) {
+            getOrientationUsingGetRotationMatrix();
+        }
     }
 
-    void getOrientationUsingGetRotationMatrix() {
-        if (mGravityVector == null || mMagneticFieldVector == null) {
+    private void getOrientationUsingGetRotationMatrix() {
+        if (mAccelerationVector == null || mMagneticFieldVector == null) {
             return;
         }
 
         // Get the rotation matrix.
         // The rotation matrix that transforms from the body frame to the earth
         // frame.
         float[] deviceRotationMatrix = new float[9];
-        if (!SensorManager.getRotationMatrix(deviceRotationMatrix, null, mGravityVector,
+        if (!SensorManager.getRotationMatrix(deviceRotationMatrix, null, mAccelerationVector,
                 mMagneticFieldVector)) {
             return;
         }
 
         // Convert rotation matrix to rotation angles.
         // Assuming that the rotations are appied in the order listed at
         // http://developer.android.com/reference/android/hardware/SensorEvent.html#values
         // the rotations are applied about the same axes and in the same order as required by the
         // API. The only conversions are sign changes as follows.  The angles are in radians
 
@@ skipping 11 matching lines @@
         }
 
         double gamma = Math.toDegrees(rotationAngles[2]);
         while (gamma < -90.0) {
             gamma += 360.0; // [-90, 90)
         }
 
         gotOrientation(alpha, beta, gamma);
     }
 
-    boolean registerForSensors(int rateInMilliseconds) {
-        if (registerForSensorType(Sensor.TYPE_ACCELEROMETER, rateInMilliseconds)
-                && registerForSensorType(Sensor.TYPE_MAGNETIC_FIELD, rateInMilliseconds)) {
-            return true;
-        }
-        unregisterForSensors();
-        return false;
-    }
-
     private SensorManager getSensorManager() {
         if (mSensorManager != null) {
             return mSensorManager;
         }
         mSensorManager = (SensorManager)WeakContext.getSystemService(Context.SENSOR_SERVICE);
         return mSensorManager;
     }
 
-    void unregisterForSensors() {
-        SensorManager sensorManager = getSensorManager();
-        if (sensorManager == null) {
-            return;
+    private void setActiveEventType(int eventType, boolean value) {
+        switch (eventType) {
+            case DEVICE_ORIENTATION:
+                mDeviceOrientationIsActive = value;
+                return;
+            case DEVICE_MOTION:
+                mDeviceMotionIsActive = value;
+                return;
         }
-        sensorManager.unregisterListener(this);
+    }
+
+    /**
+     * @param sensorTypes List of sensors to activate.
+     * @param rateInMilliseconds Intented delay (in milliseconds) between sensor readings.
+     * @param failOnMissingSensor If true the method returns true only if all sensors could be
+     *                            activated. When false the method return true if at least one
+     *                            sensor in sensorTypes could be activated.
+     */
+    private boolean registerSensors(Iterable<Integer> sensorTypes, int rateInMilliseconds,
+                                       boolean failOnMissingSensor) {
+        Set<Integer> sensorsToActivate = Sets.newHashSet(sensorTypes);
+        sensorsToActivate.removeAll(mActiveSensors);
+        boolean success = false;
+
+        for (Integer sensorType : sensorsToActivate) {
+            boolean result = registerForSensorType(sensorType, rateInMilliseconds);
+            if (!result && failOnMissingSensor) {
+                // restore the previous state upon failure
+                unregisterSensors(sensorsToActivate);
+                return false;
+            }
+            if (result) {
+                mActiveSensors.add(sensorType);
+                success = true;
+            }
+        }
+        return success;
+    }
+
+    private void unregisterSensors(Iterable<Integer> sensorTypes) {
+        for (Integer sensorType : sensorTypes) {
+            if (mActiveSensors.contains(sensorType)) {
+                List<Sensor> sensors = getSensorManager().getSensorList(sensorType);
+                if (!sensors.isEmpty()) {
+                    getSensorManager().unregisterListener(this, sensors.get(0));
+                    mActiveSensors.remove(sensorType);
+                }
+            }
+        }
     }
 
     boolean registerForSensorType(int type, int rateInMilliseconds) {
         SensorManager sensorManager = getSensorManager();
         if (sensorManager == null) {
             return false;
         }
         List<Sensor> sensors = sensorManager.getSensorList(type);
         if (sensors.isEmpty()) {
             return false;
         }
 
         final int rateInMicroseconds = 1000 * rateInMilliseconds;
-        // We want to err on the side of getting more events than we need.
-        final int requestedRate = rateInMicroseconds / 2;
-
-        // TODO(steveblock): Consider handling multiple sensors.
-        return sensorManager.registerListener(this, sensors.get(0), requestedRate, getHandler());
+        return sensorManager.registerListener(this, sensors.get(0), rateInMicroseconds,
+                                              getHandler());

[Peter Beverloo, 2013/03/13 16:18:57]

nit: 8 space indent.

[timvolodine, 2013/03/13 17:53:02]

Done.

     }
 
-    void gotOrientation(double alpha, double beta, double gamma) {
+    private void gotOrientation(double alpha, double beta, double gamma) {
         synchronized (mNativePtrLock) {
             if (mNativePtr != 0) {
               nativeGotOrientation(mNativePtr, alpha, beta, gamma);
             }
         }
     }
 
+    private void gotAcceleration(double x, double y, double z) {
+        synchronized (mNativePtrLock) {
+            if (mNativePtr != 0) {
+              nativeGotAcceleration(mNativePtr, x, y, z);
+            }
+        }
+    }
+
+    private void gotAccelerationIncludingGravity(double x, double y, double z) {
+        synchronized (mNativePtrLock) {
+            if (mNativePtr != 0) {
+              nativeGotAccelerationIncludingGravity(mNativePtr, x, y, z);
+            }
+        }
+    }
+
+    private void gotRotationRate(double alpha, double beta, double gamma) {
+        synchronized (mNativePtrLock) {
+            if (mNativePtr != 0) {
+              nativeGotRotationRate(mNativePtr, alpha, beta, gamma);
+            }
+        }
+    }
+
     private Handler getHandler() {
         synchronized (mHandlerLock) {
             // If we don't have a background thread, start it now.
             if (mThread == null) {
                 mThread = new Thread(new Runnable() {
                     @Override
                     public void run() {
                         Looper.prepare();
                         // Our Handler doesn't actually have to do anything, because
                         // SensorManager posts directly to the underlying Looper.
@@ skipping 17 matching lines @@
     }
 
     private void setHandler(Handler handler) {
         synchronized (mHandlerLock) {
             mHandler = handler;
             mHandlerLock.notify();
         }
     }
 
     @CalledByNative
-    private static DeviceOrientation getInstance() {
+    private static DeviceMotionAndOrientation getInstance() {
         synchronized (sSingletonLock) {
             if (sSingleton == null) {
-                sSingleton = new DeviceOrientation();
+                sSingleton = new DeviceMotionAndOrientation();
             }
             return sSingleton;
         }
     }
 
     /**
-     * See chrome/browser/device_orientation/data_fetcher_impl_android.cc
+     * Native JNI calls,
+     * see content/browser/device_orientation/data_fetcher_impl_android.cc
+     */
+
+    /**
+     * Orientation of the device with respect to its reference frame.
      */
     private native void nativeGotOrientation(
             int nativeDataFetcherImplAndroid,
             double alpha, double beta, double gamma);
-}
+
+    /**
+     * Linear acceleration without gravity of the device with respect to its body frame.
+     */
+    private native void nativeGotAcceleration(
+            int nativeDataFetcherImplAndroid,
+            double x, double y, double z);
+
+    /**
+     * Acceleration including gravity of the device with respect to its body frame.
+     */
+    private native void nativeGotAccelerationIncludingGravity(
+            int nativeDataFetcherImplAndroid,
+            double x, double y, double z);
+
+    /**
+     * Rotation rate of the device with respect to its body frame.
+     */
+    private native void nativeGotRotationRate(
+            int nativeDataFetcherImplAndroid,
+            double alpha, double beta, double gamma);
+
+}