Popup route.

popup_route.dart

PopupRoute
I read flutter framework code and found out showDialog is actually using PopupRoute. Basically, this will create a new route and make the previous routepage inactive.

The simplest code is as follows:

class MyPopupRoute extends PopupRoute<void> {
  @override
  Color get barrierColor => Colors.black54;

  @override
  bool get barrierDismissible => true;
  @override
  String get barrierLabel => "Close";

  @override
  Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) => MyPopupPage();

  @override
  Duration get transitionDuration => const Duration(milliseconds: 300);
}
where MyPopupPage is the new popup widget.

If you want animations, you can override the method buildTransitions method.