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      1 /*
      2  * Copyright (C) 2015 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 com.android.camera.hardware;
     18 
     19 import com.android.camera.debug.Log;
     20 
     21 import android.hardware.Sensor;
     22 import android.hardware.SensorEvent;
     23 import android.hardware.SensorEventListener;
     24 import android.hardware.SensorManager;
     25 
     26 /**
     27  * A virtual sensor that reports device heading based on information
     28  * provided by accelerometer sensor or magnetic sensor.
     29  */
     30 public class HeadingSensor implements SensorEventListener {
     31     private static final Log.Tag TAG = new Log.Tag("HeadingSensor");
     32 
     33     /** Invalid heading values. */
     34     public static final int INVALID_HEADING = -1;
     35     /** Current device heading. */
     36     private int mHeading = INVALID_HEADING;
     37 
     38     /** Device sensor manager. */
     39     private final SensorManager mSensorManager;
     40     /** Accelerometer. */
     41     private final Sensor mAccelerometerSensor;
     42     /** Compass. */
     43     private final Sensor mMagneticSensor;
     44 
     45     /** Accelerometer data. */
     46     private final float[] mGData = new float[3];
     47     /** Magnetic sensor data. */
     48     private final float[] mMData = new float[3];
     49     /** Temporary rotation matrix. */
     50     private final float[] mRotationMatrix = new float[16];
     51 
     52     /**
     53      * Constructs a heading sensor.
     54      *
     55      * @param sensorManager A {#link android.hardware.SensorManager} that
     56      *                      provides access to device sensors.
     57      */
     58     public HeadingSensor(SensorManager sensorManager) {
     59         mSensorManager = sensorManager;
     60         mAccelerometerSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
     61         mMagneticSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
     62     }
     63 
     64     /**
     65      * Returns current device heading.
     66      *
     67      * @return current device heading in degrees. INVALID_HEADING if sensors
     68      *         are not available.
     69      */
     70     public int getCurrentHeading() {
     71         return mHeading;
     72     }
     73 
     74     /**
     75      * Activates corresponding device sensors to start calculating device heading.
     76      * This would increase power consumption.
     77      */
     78     public void activate() {
     79         // Get events from the accelerometer and magnetic sensor.
     80         if (mAccelerometerSensor != null) {
     81             mSensorManager.registerListener(this, mAccelerometerSensor,
     82                     SensorManager.SENSOR_DELAY_NORMAL);
     83         }
     84         if (mMagneticSensor != null) {
     85             mSensorManager.registerListener(this, mMagneticSensor,
     86                     SensorManager.SENSOR_DELAY_NORMAL);
     87         }
     88     }
     89 
     90     /**
     91      * Deactivates corresponding device sensors to stop calculating device heading.
     92      */
     93     public void deactivate() {
     94         // Unregister the sensors.
     95         if (mAccelerometerSensor != null) {
     96             mSensorManager.unregisterListener(this, mAccelerometerSensor);
     97         }
     98         if (mMagneticSensor != null) {
     99             mSensorManager.unregisterListener(this, mMagneticSensor);
    100         }
    101     }
    102 
    103     @Override
    104     public void onSensorChanged(SensorEvent event) {
    105         // This is literally the same as the GCamModule implementation.
    106         int type = event.sensor.getType();
    107         float[] data;
    108         if (type == Sensor.TYPE_ACCELEROMETER) {
    109             data = mGData;
    110         } else if (type == Sensor.TYPE_MAGNETIC_FIELD) {
    111             data = mMData;
    112         } else {
    113             Log.w(TAG, String.format("Unexpected sensor type %s", event.sensor.getName()));
    114             return;
    115         }
    116         for (int i = 0; i < 3; i++) {
    117             data[i] = event.values[i];
    118         }
    119         float[] orientation = new float[3];
    120         SensorManager.getRotationMatrix(mRotationMatrix, null, mGData, mMData);
    121         SensorManager.getOrientation(mRotationMatrix, orientation);
    122         mHeading = (int) (orientation[0] * 180f / Math.PI) % 360;
    123 
    124         if (mHeading < 0) {
    125             mHeading += 360;
    126         }
    127     }
    128 
    129     @Override
    130     public void onAccuracyChanged(Sensor sensor, int accuracy) {
    131     }
    132 }
    133