Override this method to build the primary content of this route.
contextThe context in which the route is being built.animationThe animation for this route's transition. When entering, the animation runs forward from 0.0 to 1.0. When exiting, this animation runs backwards from 1.0 to 0.0.forwardAnimationThe animation for the route being pushed on top of this route. This animation lets this route coordinate with the entrance and exit transition of routes pushed on top of this route.
Source
Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> forwardAnimation);