transitionsBuilder property
Override this method to wrap the child with one or more transition widgets that define how the route arrives on and leaves the screen.
By default, the child (which contains the widget returned by buildPage) is not wrapped in any transition widgets.
The transitionsBuilder method, is called each time the Route's state changes while it is visible (e.g. if the value of canPop changes on the active route).
The transitionsBuilder method is typically used to define transitions that animate the new topmost route's comings and goings. When the Navigator pushes a route on the top of its stack, the new route's primary animation runs from 0.0 to 1.0. When the Navigator pops the topmost route, e.g. because the use pressed the back button, the primary animation runs from 1.0 to 0.0.
Implementation
final Widget Function(BuildContext context, Animation<double> animation,
Animation<double> secondaryAnimation, Widget child) transitionsBuilder;