Back swipe navigation gesture

back_swipe.dart

class BackSwipe extends StatelessWidget {
  final Widget child;

  BackSwipe({Key key, this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    double start = 0.0;
    return GestureDetector(
      onHorizontalDragStart: (details) => start = details.globalPosition.dx,
      onHorizontalDragUpdate: (details) {
        if (start <= MediaQuery.of(context).size.width * 0.15 && details.globalPosition.dx >= MediaQuery.of(context).size.width * 0.4) {
          Navigator.of(context).pop();
        }
      },
      child: child,
    );
  }
}