ScaleTransition({Key key, Animation<double> scale, FractionalOffset alignment: FractionalOffset.center, Widget child })

Creates a scale transition.

The scale argument is required. The alignment argument defaults to FractionalOffset.center.

Source 

ScaleTransition({
  Key key,
  Animation<double> scale,
  this.alignment: FractionalOffset.center,
  this.child
}) : super(key: key, animation: scale);