onInit method
Called immediately after the widget is allocated in memory. You might use this to initialize something for the controller.
Implementation
@override
void onInit() {
  WidgetsBinding.instance.addObserver(this);
  if (cameras.isNotEmpty) {
    isCameraSupported.value = true;
    onNewCameraSelected(cameras[0]);
  } else {
    isCameraSupported.value = false;
  }
  sensorStream = accelerometerEventStream()
      .map<DeviceOrientation>(Utils.getOrientation)
      .distinct();
  sensorStream.listen((event) {
    currentOrientation = event;
  });
  super.onInit();
}