TrainHoppingAnimation constructor

TrainHoppingAnimation(Animation<double> _currentTrain, Animation<double> _nextTrain, { VoidCallback onSwitchedTrain })

Creates a train-hopping animation.

The current train argument must not be null but the next train argument can be null. If the next train is null, then this object will just proxy the first animation and never hop.

Implementation 

TrainHoppingAnimation(this._currentTrain, this._nextTrain, { this.onSwitchedTrain })
  : assert(_currentTrain != null) {
  if (_nextTrain != null) {
    if (_currentTrain.value == _nextTrain.value) {
      _currentTrain = _nextTrain;
      _nextTrain = null;
    } else if (_currentTrain.value > _nextTrain.value) {
      _mode = _TrainHoppingMode.maximize;
    } else {
      assert(_currentTrain.value < _nextTrain.value);
      _mode = _TrainHoppingMode.minimize;
    }
  }
  _currentTrain.addStatusListener(_statusChangeHandler);
  _currentTrain.addListener(_valueChangeHandler);
  _nextTrain?.addListener(_valueChangeHandler);
  assert(_mode != null || _nextTrain == null);
}