Getting android device orientation relatively to north

OrientationTracker.scala

package android

import android.app.Activity
import android.content.Context
import android.hardware._

/** Listen to device Orientation changes.
  *
  * Note: if you use libgdx your the work is already done in Gdx.input.getRotationMatrix() and Gdx.input.getPitch()
  */
class OrientationTracker(activity: Activity) extends SensorEventListener {
  private val manager = activity.getSystemService(Context.SENSOR_SERVICE).asInstanceOf[SensorManager]
  private val magneticSensor = manager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD)
  private var magneticReady = false
  private val magneticValues = new Array[Float](3)
  private val accelerometerSensor = manager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER)
  private var accelerometerReady = false
  private val accelerometerValues = new Array[Float](3)
  private val rotationMatrix = new Array[Float](16)
  private val inclinationMatrix = new Array[Float](16)
  private val orientationVector = new Array[Float](3)
  var orientation: Option[Double] = None

  def onDestroy() = {
    manager.unregisterListener(this)
  }

  def onResume() = {
    magneticReady = false
    accelerometerReady = false
    manager.registerListener(this, magneticSensor, SensorManager.SENSOR_DELAY_GAME)
    manager.registerListener(this, accelerometerSensor, SensorManager.SENSOR_DELAY_GAME)
    ()
  }

  def onPause() = {
    manager.unregisterListener(this)
  }

  override def onAccuracyChanged(sensor: Sensor, value: Int) = {
  }

  override def onSensorChanged(event: SensorEvent) = {
    event.sensor.getType match {
      case Sensor.TYPE_ACCELEROMETER =>
        accelerometerReady = true
        System.arraycopy(event.values, 0, accelerometerValues, 0, 3)

      case Sensor.TYPE_MAGNETIC_FIELD =>
        magneticReady = true
        System.arraycopy(event.values, 0, magneticValues, 0, 3)
    }
    if (accelerometerReady && magneticReady){
      val success = SensorManager.getRotationMatrix(rotationMatrix, inclinationMatrix, accelerometerValues, magneticValues)
      if (success){
        SensorManager.getOrientation(rotationMatrix, orientationVector)
        orientation = Some(orientationVector(0).toDouble)
      }
      accelerometerReady = false
      magneticReady = false
    }
  }
}