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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.webkit;
     18 
     19 import android.content.Context;
     20 import android.hardware.Sensor;
     21 import android.hardware.SensorEvent;
     22 import android.hardware.SensorEventListener;
     23 import android.hardware.SensorManager;
     24 import android.os.Handler;
     25 import android.webkit.DeviceMotionAndOrientationManager;
     26 import java.lang.Runnable;
     27 import java.util.List;
     28 
     29 
     30 final class DeviceOrientationService implements SensorEventListener {
     31     // The gravity vector expressed in the body frame.
     32     private float[] mGravityVector;
     33     // The geomagnetic vector expressed in the body frame.
     34     private float[] mMagneticFieldVector;
     35 
     36     private DeviceMotionAndOrientationManager mManager;
     37     private boolean mIsRunning;
     38     private Handler mHandler;
     39     private SensorManager mSensorManager;
     40     private Context mContext;
     41     private Double mAlpha;
     42     private Double mBeta;
     43     private Double mGamma;
     44     private boolean mHaveSentErrorEvent;
     45 
     46     private static final double DELTA_DEGRESS = 1.0;
     47 
     48     public DeviceOrientationService(DeviceMotionAndOrientationManager manager, Context context) {
     49         mManager = manager;
     50         assert(mManager != null);
     51         mContext = context;
     52         assert(mContext != null);
     53      }
     54 
     55     public void start() {
     56         mIsRunning = true;
     57         registerForSensors();
     58     }
     59 
     60     public void stop() {
     61         mIsRunning = false;
     62         unregisterFromSensors();
     63     }
     64 
     65     public void suspend() {
     66         if (mIsRunning) {
     67             unregisterFromSensors();
     68         }
     69     }
     70 
     71     public void resume() {
     72         if (mIsRunning) {
     73             registerForSensors();
     74         }
     75     }
     76 
     77     private void sendErrorEvent() {
     78         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
     79         // The spec requires that each listener receives the error event only once.
     80         if (mHaveSentErrorEvent)
     81             return;
     82         mHaveSentErrorEvent = true;
     83         mHandler.post(new Runnable() {
     84             @Override
     85             public void run() {
     86                 assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
     87                 if (mIsRunning) {
     88                     // The special case of all nulls is used to signify a failure to get data.
     89                     mManager.onOrientationChange(null, null, null);
     90                 }
     91             }
     92         });
     93     }
     94 
     95     private void registerForSensors() {
     96         if (mHandler == null) {
     97             mHandler = new Handler();
     98         }
     99         if (!registerForAccelerometerSensor() || !registerForMagneticFieldSensor()) {
    100             unregisterFromSensors();
    101             sendErrorEvent();
    102         }
    103     }
    104 
    105     private void getOrientationUsingGetRotationMatrix() {
    106         if (mGravityVector == null || mMagneticFieldVector == null) {
    107             return;
    108         }
    109 
    110         // Get the rotation matrix.
    111         // The rotation matrix that transforms from the body frame to the earth frame.
    112         float[] deviceRotationMatrix = new float[9];
    113         if (!SensorManager.getRotationMatrix(
    114                 deviceRotationMatrix, null, mGravityVector, mMagneticFieldVector)) {
    115             return;
    116         }
    117 
    118         // Convert rotation matrix to rotation angles.
    119         // Assuming that the rotations are appied in the order listed at
    120         // http://developer.android.com/reference/android/hardware/SensorEvent.html#values
    121         // the rotations are applied about the same axes and in the same order as required by the
    122         // API. The only conversions are sign changes as follows.
    123         // The angles are in radians
    124         float[] rotationAngles = new float[3];
    125         SensorManager.getOrientation(deviceRotationMatrix, rotationAngles);
    126         double alpha = Math.toDegrees(-rotationAngles[0]) - 90.0;
    127         while (alpha < 0.0) { alpha += 360.0; } // [0, 360)
    128         double beta = Math.toDegrees(-rotationAngles[1]);
    129         while (beta < -180.0) { beta += 360.0; } // [-180, 180)
    130         double gamma = Math.toDegrees(rotationAngles[2]);
    131         while (gamma < -90.0) { gamma += 360.0; } // [-90, 90)
    132 
    133         maybeSendChange(alpha, beta, gamma);
    134     }
    135 
    136     private SensorManager getSensorManager() {
    137         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
    138         if (mSensorManager == null) {
    139             mSensorManager = (SensorManager) mContext.getSystemService(Context.SENSOR_SERVICE);
    140         }
    141         return mSensorManager;
    142     }
    143 
    144     private boolean registerForAccelerometerSensor() {
    145         List<Sensor> sensors = getSensorManager().getSensorList(Sensor.TYPE_ACCELEROMETER);
    146         if (sensors.isEmpty()) {
    147             return false;
    148         }
    149         // TODO: Consider handling multiple sensors.
    150         return getSensorManager().registerListener(
    151                 this, sensors.get(0), SensorManager.SENSOR_DELAY_FASTEST, mHandler);
    152     }
    153 
    154     private boolean registerForMagneticFieldSensor() {
    155         List<Sensor> sensors = getSensorManager().getSensorList(Sensor.TYPE_MAGNETIC_FIELD);
    156         if (sensors.isEmpty()) {
    157             return false;
    158         }
    159         // TODO: Consider handling multiple sensors.
    160         return getSensorManager().registerListener(
    161                 this, sensors.get(0), SensorManager.SENSOR_DELAY_FASTEST, mHandler);
    162     }
    163 
    164     private void unregisterFromSensors() {
    165         getSensorManager().unregisterListener(this);
    166     }
    167 
    168     private void maybeSendChange(double alpha, double beta, double gamma) {
    169         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
    170         if (mAlpha == null || mBeta == null || mGamma == null
    171                 || Math.abs(alpha - mAlpha) > DELTA_DEGRESS
    172                 || Math.abs(beta - mBeta) > DELTA_DEGRESS
    173                 || Math.abs(gamma - mGamma) > DELTA_DEGRESS) {
    174             mAlpha = alpha;
    175             mBeta = beta;
    176             mGamma = gamma;
    177             mManager.onOrientationChange(mAlpha, mBeta, mGamma);
    178             // Now that we have successfully sent some data, reset whether we've sent an error.
    179             mHaveSentErrorEvent = false;
    180         }
    181     }
    182 
    183     /**
    184      * SensorEventListener implementation.
    185      * Callbacks happen on the thread on which we registered - the WebCore thread.
    186      */
    187     @Override
    188     public void onSensorChanged(SensorEvent event) {
    189         assert(event.values.length == 3);
    190         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
    191 
    192         // We may get callbacks after the call to getSensorManager().unregisterListener() returns.
    193         if (!mIsRunning) {
    194             return;
    195         }
    196 
    197         switch (event.sensor.getType()) {
    198           case Sensor.TYPE_ACCELEROMETER:
    199             if (mGravityVector == null) {
    200                 mGravityVector = new float[3];
    201             }
    202             mGravityVector[0] = event.values[0];
    203             mGravityVector[1] = event.values[1];
    204             mGravityVector[2] = event.values[2];
    205             getOrientationUsingGetRotationMatrix();
    206             break;
    207           case Sensor.TYPE_MAGNETIC_FIELD:
    208             if (mMagneticFieldVector == null) {
    209                 mMagneticFieldVector = new float[3];
    210             }
    211             mMagneticFieldVector[0] = event.values[0];
    212             mMagneticFieldVector[1] = event.values[1];
    213             mMagneticFieldVector[2] = event.values[2];
    214             getOrientationUsingGetRotationMatrix();
    215             break;
    216           default:
    217             assert(false);
    218         }
    219     }
    220 
    221     @Override
    222     public void onAccuracyChanged(Sensor sensor, int accuracy) {
    223         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
    224     }
    225 }
    226