forward method

void forward()

Implementation

void forward() {
  isAnimating = true;
  final oneStep = (duration.inMicroseconds / 3).round();
  _status = AnimationStatus.forward;
  _timers = [
    Timer(
      Duration(microseconds: oneStep),
      () => setValue(1),
    ),
    Timer(
      Duration(microseconds: oneStep * 2),
      () => setValue(2),
    ),
    Timer(
      Duration(microseconds: oneStep * 3),
      () => setValue(3),
    ),
    Timer(
      Duration(microseconds: oneStep * 4),
      () {
        _status = AnimationStatus.completed;
        isAnimating = false;
        notifyListeners();
      },
    ),
  ];
}