init method

void init()

Initialization of the listen and update of the controller and variables

Implementation

void init() {
  _streamSubscriptions.add(magnetometerEvents.listen(
    (MagnetometerEvent event) {
      az = 90 - atan2(event.y, event.x) * 180 / pi;
      _azController.sink.add(az);
      az = az;
    },
  ));
}