flutter Custom PageRouteBuilder

Question

Custom Route like this：

class FadeRouteBuilder extends PageRouteBuilder {
  final Widget page;
  final int duration;


  FadeRouteBuilder({this.page, this.duration = 1000})
      : super(
          transitionDuration: Duration(milliseconds: duration),
          //Page builder doesn't do anything special, just return the ui.page we were passed in.
          pageBuilder: (context, animation, secondaryAnimation) => page,
          //transitionsBuilder builds 2 nested transitions, one for transitionIn (animation), and one for transitionOut (secondaryAnimation)
          transitionsBuilder: (context, animation, secondaryAnimation, child) {
            return FadeTransition(
                //Transition from 0 - 1 when coming on the screen
                opacity: Tween<double>(begin: 0, end: 1).animate(animation),
                child: FadeTransition(
                  //Transition from 1 to 0 when leaving the screen
                  opacity: Tween<double>(begin: 1, end: 0)
                      .animate(secondaryAnimation),
                  child: child,
                ));
          },
        );
}

A page containing CustomScrollView is PageA，to navgitor PageB by FadeRouteBuilder，

when I pop pageB，I drag PageA list and hold，when PageB closed，CustomScrollView can't tap，is invalid.

Answer 1

I use a variable to determine if Page B is closed。

Although it solves the problem, it is not elegant enough, If there is a better solution, please answer me. thanks