RelativePositionedTransition constructor Null safety

const RelativePositionedTransition(
  1. {Key? key,
  2. required Animation<Rect?> rect,
  3. required Size size,
  4. required Widget child}

Create an animated version of Positioned.

Each frame, the Positioned widget will be configured to represent the current value of the rect argument assuming that the stack has the given size. Both rect and size must not be null.


const RelativePositionedTransition({
  required Animation<Rect?> rect,
  required this.size,
  required this.child,
}) : assert(rect != null),
     assert(size != null),
     assert(child != null),
     super(listenable: rect);