start method

Implementation

start() {
  if (value <= 0) return;
  _dispose();
  Duration duration = _getDuration();
  if (duration == stepDuration) {
    _diffTimer = Timer.periodic(stepDuration, (Timer timer) {
      _diffTime(stepDuration);
    });
  } else {
    Future.delayed(duration, () {
      _diffTime(duration);
      _diffTimer = Timer.periodic(stepDuration, (Timer timer) {
        _diffTime(stepDuration);
      });
    });
  }
}