erisu commented on code in PR #78:
URL: 
https://github.com/apache/cordova-plugin-device-orientation/pull/78#discussion_r957390600


##########
src/android/CompassListener.java:
##########
@@ -38,259 +40,306 @@ Licensed to the Apache Software Foundation (ASF) under one
 import android.os.Handler;
 import android.os.Looper;
 
+import android.util.Log; // MG
+
 /**
  * This class listens to the compass sensor and stores the latest heading 
value.
  */
 public class CompassListener extends CordovaPlugin implements 
SensorEventListener {
 
-    public static int STOPPED = 0;
-    public static int STARTING = 1;
-    public static int RUNNING = 2;
-    public static int ERROR_FAILED_TO_START = 3;
-
-    public long TIMEOUT = 30000;        // Timeout in msec to shut off listener
-
-    int status;                         // status of listener
-    float heading;                      // most recent heading value
-    long timeStamp;                     // time of most recent value
-    long lastAccessTime;                // time the value was last retrieved
-    int accuracy;                       // accuracy of the sensor
-
-    private SensorManager sensorManager;// Sensor manager
-    Sensor mSensor;                     // Compass sensor returned by sensor 
manager
-
-    private CallbackContext callbackContext;
-
-    /**
-     * Constructor.
-     */
-    public CompassListener() {
-        this.heading = 0;
-        this.timeStamp = 0;
-        this.setStatus(CompassListener.STOPPED);
-    }
-
-    /**
-     * Sets the context of the Command. This can then be used to do things like
-     * get file paths associated with the Activity.
-     *
-     * @param cordova The context of the main Activity.
-     * @param webView The CordovaWebView Cordova is running in.
-     */
-    public void initialize(CordovaInterface cordova, CordovaWebView webView) {
-        super.initialize(cordova, webView);
-        this.sensorManager = (SensorManager) 
cordova.getActivity().getSystemService(Context.SENSOR_SERVICE);
-    }
-
-    /**
-     * Executes the request and returns PluginResult.
-     *
-     * @param action                The action to execute.
-     * @param args                 JSONArry of arguments for the plugin.
-     * @param callbackS=Context     The callback id used when calling back 
into JavaScript.
-     * @return                     True if the action was valid.
-     * @throws JSONException 
-     */
-    public boolean execute(String action, JSONArray args, CallbackContext 
callbackContext) throws JSONException {
-        if (action.equals("start")) {
-            this.start();
-        }
-        else if (action.equals("stop")) {
-            this.stop();
+  public static int STOPPED = 0;
+  public static int STARTING = 1;
+  public static int RUNNING = 2;
+  public static int ERROR_FAILED_TO_START = 3;
+
+  public long TIMEOUT = 30000; // Timeout in msec to shut off listener
+
+  int status; // status of listener
+  float heading; // most recent heading value
+  long timeStamp; // time of most recent value
+  long lastAccessTime; // time the value was last retrieved
+  int accuracy; // accuracy of the sensor
+
+  private SensorManager sensorManager;// Sensor manager
+  Sensor mSensor; // Compass sensor returned by sensor manager
+
+  Sensor accelerometer;
+  Sensor magnetometer;
+
+  private CallbackContext callbackContext;
+
+  /**
+   * Constructor.
+   */
+  public CompassListener() {
+    this.heading = 0;
+    this.timeStamp = 0;
+    this.setStatus(CompassListener.STOPPED);
+  }
+
+  /**
+   * Sets the context of the Command. This can then be used to do things like
+   * get file paths associated with the Activity.
+   *
+   * @param cordova The context of the main Activity.
+   * @param webView The CordovaWebView Cordova is running in.
+   */
+  public void initialize(CordovaInterface cordova, CordovaWebView webView) {
+    super.initialize(cordova, webView);
+    this.sensorManager = (SensorManager) 
cordova.getActivity().getSystemService(Context.SENSOR_SERVICE);
+  }
+
+  /**
+   * Executes the request and returns PluginResult.
+   *
+   * @param action            The action to execute.
+   * @param args              JSONArry of arguments for the plugin.
+   * @param callbackS=Context The callback id used when calling back into
+   *                          JavaScript.
+   * @return True if the action was valid.
+   * @throws JSONException
+   */
+  public boolean execute(String action, JSONArray args, CallbackContext 
callbackContext) throws JSONException {
+    if (action.equals("start")) {
+      this.start();
+    } else if (action.equals("stop")) {
+      this.stop();
+    } else if (action.equals("getStatus")) {
+      int i = this.getStatus();
+      callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, i));
+    } else if (action.equals("getHeading")) {
+      // If not running, then this is an async call, so don't worry about 
waiting
+      if (this.status != CompassListener.RUNNING) {
+        int r = this.start();
+        if (r == CompassListener.ERROR_FAILED_TO_START) {
+          callbackContext.sendPluginResult(
+              new PluginResult(PluginResult.Status.IO_EXCEPTION, 
CompassListener.ERROR_FAILED_TO_START));
+          return true;
         }
-        else if (action.equals("getStatus")) {
-            int i = this.getStatus();
-            callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, i));
-        }
-        else if (action.equals("getHeading")) {
-            // If not running, then this is an async call, so don't worry 
about waiting
-            if (this.status != CompassListener.RUNNING) {
-                int r = this.start();
-                if (r == CompassListener.ERROR_FAILED_TO_START) {
-                    callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.IO_EXCEPTION, 
CompassListener.ERROR_FAILED_TO_START));
-                    return true;
-                }
-                // Set a timeout callback on the main thread.
-                Handler handler = new Handler(Looper.getMainLooper());
-                handler.postDelayed(new Runnable() {
-                    public void run() {
-                        CompassListener.this.timeout();
-                    }
-                }, 2000);
-            }
-            callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, getCompassHeading()));
-        }
-        else if (action.equals("setTimeout")) {
-            this.setTimeout(args.getLong(0));
-        }
-        else if (action.equals("getTimeout")) {
-            long l = this.getTimeout();
-            callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, l));
-        } else {
-            // Unsupported action
-            return false;
-        }
-        return true;
-    }
-
-    /**
-     * Called when listener is to be shut down and object is being destroyed.
-     */
-    public void onDestroy() {
-        this.stop();
+        // Set a timeout callback on the main thread.
+        Handler handler = new Handler(Looper.getMainLooper());
+        handler.postDelayed(new Runnable() {
+          public void run() {
+            CompassListener.this.timeout();
+          }
+        }, 2000);
+      }
+      callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, getCompassHeading()));
+    } else if (action.equals("setTimeout")) {
+      this.setTimeout(args.getLong(0));
+    } else if (action.equals("getTimeout")) {
+      long l = this.getTimeout();
+      callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, l));
+    } else {
+      // Unsupported action
+      return false;
     }
-
-    /**
-     * Called when app has navigated and JS listeners have been destroyed.
-     */
-    public void onReset() {
-        this.stop();
-    }
-
-    
//--------------------------------------------------------------------------
-    // LOCAL METHODS
-    
//--------------------------------------------------------------------------
-
-    /**
-     * Start listening for compass sensor.
-     *
-     * @return          status of listener
-     */
-    public int start() {
-
-        // If already starting or running, then just return
-        if ((this.status == CompassListener.RUNNING) || (this.status == 
CompassListener.STARTING)) {
-            return this.status;
-        }
-
-        // Get compass sensor from sensor manager
-        @SuppressWarnings("deprecation")
-        List<Sensor> list = 
this.sensorManager.getSensorList(Sensor.TYPE_ORIENTATION);
-
-        // If found, then register as listener
-        if (list != null && list.size() > 0) {
-            this.mSensor = list.get(0);
-            this.sensorManager.registerListener(this, this.mSensor, 
SensorManager.SENSOR_DELAY_NORMAL);
-            this.lastAccessTime = System.currentTimeMillis();
-            this.setStatus(CompassListener.STARTING);
-        }
-
-        // If error, then set status to error
-        else {
-            this.setStatus(CompassListener.ERROR_FAILED_TO_START);
-        }
-
-        return this.status;
+    return true;
+  }
+
+  /**
+   * Called when listener is to be shut down and object is being destroyed.
+   */
+  public void onDestroy() {
+    this.stop();
+  }
+
+  /**
+   * Called when app has navigated and JS listeners have been destroyed.
+   */
+  public void onReset() {
+    this.stop();
+  }
+
+  // --------------------------------------------------------------------------
+  // LOCAL METHODS
+  // --------------------------------------------------------------------------
+
+  /**
+   * Start listening for compass sensor.
+   *
+   * @return status of listener
+   */
+  public int start() {
+
+    // If already starting or running, then just return
+    if ((this.status == CompassListener.RUNNING) || (this.status == 
CompassListener.STARTING)) {
+      return this.status;
     }
 
-    /**
-     * Stop listening to compass sensor.
-     */
-    public void stop() {
-        if (this.status != CompassListener.STOPPED) {
-            this.sensorManager.unregisterListener(this);
-        }
-        this.setStatus(CompassListener.STOPPED);
+    // MG, use accelerometer & magnetometer
+    // 
http://web.archive.org/web/20151205103652/http://www.codingforandroid.com/2011/01/using-orientation-sensors-simple.html
+    // 
https://android-developers.googleblog.com/2010/09/one-screen-turn-deserves-another.html
+    // 
https://stackoverflow.com/questions/15537125/inconsistent-orientation-sensor-values-on-android-for-azimuth-yaw-and-roll/16418016#16418016
+    accelerometer = 
this.sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
+    magnetometer = 
this.sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
+    if (accelerometer != null || magnetometer != null) {
+      this.sensorManager.registerListener(this, this.magnetometer, 
SensorManager.SENSOR_DELAY_NORMAL);
+      this.sensorManager.registerListener(this, this.accelerometer, 
SensorManager.SENSOR_DELAY_NORMAL);
+      this.lastAccessTime = System.currentTimeMillis();
+      this.setStatus(CompassListener.STARTING);
+
+    } else {
+      // If error, then set status to error
+      this.setStatus(CompassListener.ERROR_FAILED_TO_START);
     }
-
-    public void onAccuracyChanged(Sensor sensor, int accuracy) {
-        // TODO Auto-generated method stub
+    return this.status;
+  }
+
+  /**
+   * Stop listening to compass sensor.
+   */
+  public void stop() {
+    if (this.status != CompassListener.STOPPED) {
+      this.sensorManager.unregisterListener(this);
     }
-
-    /**
-     * Called after a delay to time out if the listener has not attached fast 
enough.
-     */
-    private void timeout() {
-        if (this.status == CompassListener.STARTING) {
-            this.setStatus(CompassListener.ERROR_FAILED_TO_START);
-            if (this.callbackContext != null) {
-                this.callbackContext.error("Compass listener failed to 
start.");
-            }
-        }
+    this.setStatus(CompassListener.STOPPED);
+  }
+
+  public void onAccuracyChanged(Sensor sensor, int accuracy) {
+    // TODO Auto-generated method stub
+  }
+
+  /**
+   * Called after a delay to time out if the listener has not attached fast
+   * enough.
+   */
+  private void timeout() {
+    if (this.status == CompassListener.STARTING) {
+      this.setStatus(CompassListener.ERROR_FAILED_TO_START);
+      if (this.callbackContext != null) {
+        this.callbackContext.error("Compass listener failed to start.");
+      }
     }
-
-    /**
-     * Sensor listener event.
-     *
-     * @param SensorEvent event
-     */
-    public void onSensorChanged(SensorEvent event) {
-
-        // We only care about the orientation as far as it refers to Magnetic 
North
-        float heading = event.values[0];
-
-        // Save heading
-        this.timeStamp = System.currentTimeMillis();
-        this.heading = heading;
-        this.setStatus(CompassListener.RUNNING);
-
-        // If heading hasn't been read for TIMEOUT time, then turn off compass 
sensor to save power
-        if ((this.timeStamp - this.lastAccessTime) > this.TIMEOUT) {
-            this.stop();
+  }
+
+  private float gravity[] = null;
+  private float magnetic[] = null;
+
+  private float toDeg(float x) {
+    return x * 180 / (float) Math.PI; // Convert to degrees
+  }
+
+  /**
+   * Sensor listener event.
+   *
+   * @param SensorEvent event
+   */
+  @SuppressWarnings("deprecation")
+  public void onSensorChanged(SensorEvent event) {
+    float alpha = (float) 0.5; // low pass filter;
+    float heading = (0f / 0f); // NaN
+    switch (event.sensor.getType()) {
+      case Sensor.TYPE_ACCELEROMETER:
+        // Isolate the force of gravity with the low-pass filter.
+        if (gravity == null) {
+          gravity = new float[3];
         }
+        gravity[0] = alpha * gravity[0] + (1 - alpha) * event.values[0];
+        gravity[1] = alpha * gravity[1] + (1 - alpha) * event.values[1];
+        gravity[2] = alpha * gravity[2] + (1 - alpha) * event.values[2];
+        break;
+      case Sensor.TYPE_MAGNETIC_FIELD:
+        magnetic = event.values;
+        break;
     }
-
-    /**
-     * Get status of compass sensor.
-     *
-     * @return          status
-     */
-    public int getStatus() {
-        return this.status;
-    }
-
-    /**
-     * Get the most recent compass heading.
-     *
-     * @return          heading
-     */
-    public float getHeading() {
-        this.lastAccessTime = System.currentTimeMillis();
-        return this.heading;
+    if (isNaN(heading) && gravity != null && magnetic != null) {
+      float R[] = new float[9];
+      float I[] = new float[9];
+      boolean success = SensorManager.getRotationMatrix(R, I, gravity, 
magnetic);
+      if (success) {
+        // Android recommands using SensorManager.getOrientation() but it has 
a wontFix
+        // bug:
+        // 
https://stackoverflow.com/questions/67824884/pitch-returned-by-getorientation-function-is-wrong
+        // So we use Stochastically's method:
+        // 
https://stackoverflow.com/questions/15537125/inconsistent-orientation-sensor-values-on-android-for-azimuth-yaw-and-roll/16418016#16418016
+        // which works like a charm.
+        // Beware also of screen orientation:
+        // 
https://android-developers.googleblog.com/2010/09/one-screen-turn-deserves-another.html
+
+        heading = (float) Math.atan2((double) (R[1] - R[3]), (double) (R[0] + 
R[4]));
+        heading = toDeg(heading);
+        // Log.v("MGMG", "heading: " + heading);

Review Comment:
   Remove



##########
src/android/CompassListener.java:
##########
@@ -38,259 +40,306 @@ Licensed to the Apache Software Foundation (ASF) under one
 import android.os.Handler;
 import android.os.Looper;
 
+import android.util.Log; // MG
+
 /**
  * This class listens to the compass sensor and stores the latest heading 
value.
  */
 public class CompassListener extends CordovaPlugin implements 
SensorEventListener {
 
-    public static int STOPPED = 0;
-    public static int STARTING = 1;
-    public static int RUNNING = 2;
-    public static int ERROR_FAILED_TO_START = 3;
-
-    public long TIMEOUT = 30000;        // Timeout in msec to shut off listener
-
-    int status;                         // status of listener
-    float heading;                      // most recent heading value
-    long timeStamp;                     // time of most recent value
-    long lastAccessTime;                // time the value was last retrieved
-    int accuracy;                       // accuracy of the sensor
-
-    private SensorManager sensorManager;// Sensor manager
-    Sensor mSensor;                     // Compass sensor returned by sensor 
manager
-
-    private CallbackContext callbackContext;
-
-    /**
-     * Constructor.
-     */
-    public CompassListener() {
-        this.heading = 0;
-        this.timeStamp = 0;
-        this.setStatus(CompassListener.STOPPED);
-    }
-
-    /**
-     * Sets the context of the Command. This can then be used to do things like
-     * get file paths associated with the Activity.
-     *
-     * @param cordova The context of the main Activity.
-     * @param webView The CordovaWebView Cordova is running in.
-     */
-    public void initialize(CordovaInterface cordova, CordovaWebView webView) {
-        super.initialize(cordova, webView);
-        this.sensorManager = (SensorManager) 
cordova.getActivity().getSystemService(Context.SENSOR_SERVICE);
-    }
-
-    /**
-     * Executes the request and returns PluginResult.
-     *
-     * @param action                The action to execute.
-     * @param args                 JSONArry of arguments for the plugin.
-     * @param callbackS=Context     The callback id used when calling back 
into JavaScript.
-     * @return                     True if the action was valid.
-     * @throws JSONException 
-     */
-    public boolean execute(String action, JSONArray args, CallbackContext 
callbackContext) throws JSONException {
-        if (action.equals("start")) {
-            this.start();
-        }
-        else if (action.equals("stop")) {
-            this.stop();
+  public static int STOPPED = 0;
+  public static int STARTING = 1;
+  public static int RUNNING = 2;
+  public static int ERROR_FAILED_TO_START = 3;
+
+  public long TIMEOUT = 30000; // Timeout in msec to shut off listener
+
+  int status; // status of listener
+  float heading; // most recent heading value
+  long timeStamp; // time of most recent value
+  long lastAccessTime; // time the value was last retrieved
+  int accuracy; // accuracy of the sensor
+
+  private SensorManager sensorManager;// Sensor manager
+  Sensor mSensor; // Compass sensor returned by sensor manager
+
+  Sensor accelerometer;
+  Sensor magnetometer;
+
+  private CallbackContext callbackContext;
+
+  /**
+   * Constructor.
+   */
+  public CompassListener() {
+    this.heading = 0;
+    this.timeStamp = 0;
+    this.setStatus(CompassListener.STOPPED);
+  }
+
+  /**
+   * Sets the context of the Command. This can then be used to do things like
+   * get file paths associated with the Activity.
+   *
+   * @param cordova The context of the main Activity.
+   * @param webView The CordovaWebView Cordova is running in.
+   */
+  public void initialize(CordovaInterface cordova, CordovaWebView webView) {
+    super.initialize(cordova, webView);
+    this.sensorManager = (SensorManager) 
cordova.getActivity().getSystemService(Context.SENSOR_SERVICE);
+  }
+
+  /**
+   * Executes the request and returns PluginResult.
+   *
+   * @param action            The action to execute.
+   * @param args              JSONArry of arguments for the plugin.
+   * @param callbackS=Context The callback id used when calling back into
+   *                          JavaScript.
+   * @return True if the action was valid.
+   * @throws JSONException
+   */
+  public boolean execute(String action, JSONArray args, CallbackContext 
callbackContext) throws JSONException {
+    if (action.equals("start")) {
+      this.start();
+    } else if (action.equals("stop")) {
+      this.stop();
+    } else if (action.equals("getStatus")) {
+      int i = this.getStatus();
+      callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, i));
+    } else if (action.equals("getHeading")) {
+      // If not running, then this is an async call, so don't worry about 
waiting
+      if (this.status != CompassListener.RUNNING) {
+        int r = this.start();
+        if (r == CompassListener.ERROR_FAILED_TO_START) {
+          callbackContext.sendPluginResult(
+              new PluginResult(PluginResult.Status.IO_EXCEPTION, 
CompassListener.ERROR_FAILED_TO_START));
+          return true;
         }
-        else if (action.equals("getStatus")) {
-            int i = this.getStatus();
-            callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, i));
-        }
-        else if (action.equals("getHeading")) {
-            // If not running, then this is an async call, so don't worry 
about waiting
-            if (this.status != CompassListener.RUNNING) {
-                int r = this.start();
-                if (r == CompassListener.ERROR_FAILED_TO_START) {
-                    callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.IO_EXCEPTION, 
CompassListener.ERROR_FAILED_TO_START));
-                    return true;
-                }
-                // Set a timeout callback on the main thread.
-                Handler handler = new Handler(Looper.getMainLooper());
-                handler.postDelayed(new Runnable() {
-                    public void run() {
-                        CompassListener.this.timeout();
-                    }
-                }, 2000);
-            }
-            callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, getCompassHeading()));
-        }
-        else if (action.equals("setTimeout")) {
-            this.setTimeout(args.getLong(0));
-        }
-        else if (action.equals("getTimeout")) {
-            long l = this.getTimeout();
-            callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, l));
-        } else {
-            // Unsupported action
-            return false;
-        }
-        return true;
-    }
-
-    /**
-     * Called when listener is to be shut down and object is being destroyed.
-     */
-    public void onDestroy() {
-        this.stop();
+        // Set a timeout callback on the main thread.
+        Handler handler = new Handler(Looper.getMainLooper());
+        handler.postDelayed(new Runnable() {
+          public void run() {
+            CompassListener.this.timeout();
+          }
+        }, 2000);
+      }
+      callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, getCompassHeading()));
+    } else if (action.equals("setTimeout")) {
+      this.setTimeout(args.getLong(0));
+    } else if (action.equals("getTimeout")) {
+      long l = this.getTimeout();
+      callbackContext.sendPluginResult(new 
PluginResult(PluginResult.Status.OK, l));
+    } else {
+      // Unsupported action
+      return false;
     }
-
-    /**
-     * Called when app has navigated and JS listeners have been destroyed.
-     */
-    public void onReset() {
-        this.stop();
-    }
-
-    
//--------------------------------------------------------------------------
-    // LOCAL METHODS
-    
//--------------------------------------------------------------------------
-
-    /**
-     * Start listening for compass sensor.
-     *
-     * @return          status of listener
-     */
-    public int start() {
-
-        // If already starting or running, then just return
-        if ((this.status == CompassListener.RUNNING) || (this.status == 
CompassListener.STARTING)) {
-            return this.status;
-        }
-
-        // Get compass sensor from sensor manager
-        @SuppressWarnings("deprecation")
-        List<Sensor> list = 
this.sensorManager.getSensorList(Sensor.TYPE_ORIENTATION);
-
-        // If found, then register as listener
-        if (list != null && list.size() > 0) {
-            this.mSensor = list.get(0);
-            this.sensorManager.registerListener(this, this.mSensor, 
SensorManager.SENSOR_DELAY_NORMAL);
-            this.lastAccessTime = System.currentTimeMillis();
-            this.setStatus(CompassListener.STARTING);
-        }
-
-        // If error, then set status to error
-        else {
-            this.setStatus(CompassListener.ERROR_FAILED_TO_START);
-        }
-
-        return this.status;
+    return true;
+  }
+
+  /**
+   * Called when listener is to be shut down and object is being destroyed.
+   */
+  public void onDestroy() {
+    this.stop();
+  }
+
+  /**
+   * Called when app has navigated and JS listeners have been destroyed.
+   */
+  public void onReset() {
+    this.stop();
+  }
+
+  // --------------------------------------------------------------------------
+  // LOCAL METHODS
+  // --------------------------------------------------------------------------
+
+  /**
+   * Start listening for compass sensor.
+   *
+   * @return status of listener
+   */
+  public int start() {
+
+    // If already starting or running, then just return
+    if ((this.status == CompassListener.RUNNING) || (this.status == 
CompassListener.STARTING)) {
+      return this.status;
     }
 
-    /**
-     * Stop listening to compass sensor.
-     */
-    public void stop() {
-        if (this.status != CompassListener.STOPPED) {
-            this.sensorManager.unregisterListener(this);
-        }
-        this.setStatus(CompassListener.STOPPED);
+    // MG, use accelerometer & magnetometer
+    // 
http://web.archive.org/web/20151205103652/http://www.codingforandroid.com/2011/01/using-orientation-sensors-simple.html
+    // 
https://android-developers.googleblog.com/2010/09/one-screen-turn-deserves-another.html
+    // 
https://stackoverflow.com/questions/15537125/inconsistent-orientation-sensor-values-on-android-for-azimuth-yaw-and-roll/16418016#16418016
+    accelerometer = 
this.sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
+    magnetometer = 
this.sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
+    if (accelerometer != null || magnetometer != null) {
+      this.sensorManager.registerListener(this, this.magnetometer, 
SensorManager.SENSOR_DELAY_NORMAL);
+      this.sensorManager.registerListener(this, this.accelerometer, 
SensorManager.SENSOR_DELAY_NORMAL);
+      this.lastAccessTime = System.currentTimeMillis();
+      this.setStatus(CompassListener.STARTING);
+
+    } else {
+      // If error, then set status to error
+      this.setStatus(CompassListener.ERROR_FAILED_TO_START);
     }
-
-    public void onAccuracyChanged(Sensor sensor, int accuracy) {
-        // TODO Auto-generated method stub
+    return this.status;
+  }
+
+  /**
+   * Stop listening to compass sensor.
+   */
+  public void stop() {
+    if (this.status != CompassListener.STOPPED) {
+      this.sensorManager.unregisterListener(this);
     }
-
-    /**
-     * Called after a delay to time out if the listener has not attached fast 
enough.
-     */
-    private void timeout() {
-        if (this.status == CompassListener.STARTING) {
-            this.setStatus(CompassListener.ERROR_FAILED_TO_START);
-            if (this.callbackContext != null) {
-                this.callbackContext.error("Compass listener failed to 
start.");
-            }
-        }
+    this.setStatus(CompassListener.STOPPED);
+  }
+
+  public void onAccuracyChanged(Sensor sensor, int accuracy) {
+    // TODO Auto-generated method stub
+  }
+
+  /**
+   * Called after a delay to time out if the listener has not attached fast
+   * enough.
+   */
+  private void timeout() {
+    if (this.status == CompassListener.STARTING) {
+      this.setStatus(CompassListener.ERROR_FAILED_TO_START);
+      if (this.callbackContext != null) {
+        this.callbackContext.error("Compass listener failed to start.");
+      }
     }
-
-    /**
-     * Sensor listener event.
-     *
-     * @param SensorEvent event
-     */
-    public void onSensorChanged(SensorEvent event) {
-
-        // We only care about the orientation as far as it refers to Magnetic 
North
-        float heading = event.values[0];
-
-        // Save heading
-        this.timeStamp = System.currentTimeMillis();
-        this.heading = heading;
-        this.setStatus(CompassListener.RUNNING);
-
-        // If heading hasn't been read for TIMEOUT time, then turn off compass 
sensor to save power
-        if ((this.timeStamp - this.lastAccessTime) > this.TIMEOUT) {
-            this.stop();
+  }
+
+  private float gravity[] = null;
+  private float magnetic[] = null;
+
+  private float toDeg(float x) {
+    return x * 180 / (float) Math.PI; // Convert to degrees
+  }
+
+  /**
+   * Sensor listener event.
+   *
+   * @param SensorEvent event
+   */
+  @SuppressWarnings("deprecation")
+  public void onSensorChanged(SensorEvent event) {
+    float alpha = (float) 0.5; // low pass filter;
+    float heading = (0f / 0f); // NaN
+    switch (event.sensor.getType()) {
+      case Sensor.TYPE_ACCELEROMETER:
+        // Isolate the force of gravity with the low-pass filter.
+        if (gravity == null) {
+          gravity = new float[3];
         }
+        gravity[0] = alpha * gravity[0] + (1 - alpha) * event.values[0];
+        gravity[1] = alpha * gravity[1] + (1 - alpha) * event.values[1];
+        gravity[2] = alpha * gravity[2] + (1 - alpha) * event.values[2];
+        break;
+      case Sensor.TYPE_MAGNETIC_FIELD:
+        magnetic = event.values;
+        break;
     }
-
-    /**
-     * Get status of compass sensor.
-     *
-     * @return          status
-     */
-    public int getStatus() {
-        return this.status;
-    }
-
-    /**
-     * Get the most recent compass heading.
-     *
-     * @return          heading
-     */
-    public float getHeading() {
-        this.lastAccessTime = System.currentTimeMillis();
-        return this.heading;
+    if (isNaN(heading) && gravity != null && magnetic != null) {
+      float R[] = new float[9];
+      float I[] = new float[9];
+      boolean success = SensorManager.getRotationMatrix(R, I, gravity, 
magnetic);
+      if (success) {
+        // Android recommands using SensorManager.getOrientation() but it has 
a wontFix

Review Comment:
   ```suggestion
           // Android recommends using SensorManager.getOrientation() but it 
has a wontFix
   ```



##########
src/android/CompassListener.java:
##########
@@ -38,259 +40,306 @@ Licensed to the Apache Software Foundation (ASF) under one
 import android.os.Handler;
 import android.os.Looper;
 
+import android.util.Log; // MG

Review Comment:
   This can be replaced with Apache Cordova's Logger.
   
   ```suggestion
   import org.apache.cordova.LOG;
   ```
   
   Also create a log tag for the `CompassListener` class. E.g.:
   
   ```java
   private static final String LOG_TAG = "CompassListener";
   ```
   
   Usage example after making those changes:
   
   ```java
   LOG.d(LOG_TAG, "Some message here");
   ```
   
   Since you also removed/commented out the only log line
   
   ```
   // Log.v("MGMG", "heading: " + heading);
   ```
   
   Technically you can remove the commented out line and import completely 
since your not logging anything at all..



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