_animationController = AnimationController.unbounded(vsync: this)
      ..addListener(() {
        _updateScale(_animationController.value);
      });
   
    //could have just set `vsync` to `this` if using `TickerProviderStateMixin`
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _verticalAnimationController =
          AnimationController.unbounded(vsync: _verticalController.position.context.vsync)
            ..addListener(() {
              _verticalController.jumpTo(_verticalAnimationController.value);
            });

      _horizontalAnimationController =
          AnimationController.unbounded(vsync: _horizontalController.position.context.vsync)
            ..addListener(() {
              _horizontalController.jumpTo(_horizontalAnimationController.value);
            });
    });

    _animationController = AnimationController.unbounded(vsync: this)
      ..addListener(() {
        _updateScale(_animationController.value);
      });

    _verticalAnimationController = AnimationController.unbounded(vsync: this)
      ..addListener(() {
        _verticalController.jumpTo(_verticalAnimationController.value);
      });

    _horizontalAnimationController = AnimationController.unbounded(vsync: this)
      ..addListener(() {
        _horizontalController.jumpTo(_horizontalAnimationController.value);
      });