SizeTransition({Key key, Axis axis: Axis.vertical, Animation<double> sizeFactor, double axisAlignment: 0.5, Widget child })

Creates a size transition.

The sizeFactor argument is required. The axis argument defaults to Axis.vertical. The axisAlignment defaults to 0.5, which centers the child along the main axis during the transition.

Source 

SizeTransition({
  Key key,
  this.axis: Axis.vertical,
  Animation<double> sizeFactor,
  this.axisAlignment: 0.5,
  this.child
}) : super(key: key, animation: sizeFactor) {
  assert(axis != null);
}