Hibok/lib/utils/TutorialOverlay.dart

import 'package:flutter/material.dart';

class TutorialOverlay extends ModalRoute<void> {
  @override
  Duration get transitionDuration => Duration(milliseconds: 100);

  @override
  bool get opaque => false;

  @override
  bool get barrierDismissible => false;

  @override
  Color get barrierColor => Colors.black.withOpacity(0.5);

  @override
  String get barrierLabel => null;

  @override
  bool get maintainState => true;

  final child;

  TutorialOverlay({this.child});

  @override
  Widget buildPage(
    BuildContext context,
    Animation<double> animation,
    Animation<double> secondaryAnimation,
  ) {
    // This makes sure that text and other content follows the material style
    return Material(
      type: MaterialType.transparency,
      // make sure that the overlay content is not cut off
      child: SafeArea(
        child: child, //_buildOverlayContent(context),
      ),
    );
  }

  @override
  Widget buildTransitions(BuildContext context, Animation<double> animation,
      Animation<double> secondaryAnimation, Widget child) {
    return FadeTransition(
      opacity: animation,
      child: child,
    );
  }
}