import 'package:flutter/material.dart';

class TutorialOverlay extends ModalRoute<void> {
  @override
  Duration get transitionDuration => Duration(milliseconds: 500);

  @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;

  @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: _buildOverlayContent(context),),);
  }

  Widget _buildOverlayContent(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,children: <Widget>[
          Text(
            'This is a nice overlay',style: TextStyle(color: Colors.white,fontSize: 30.0),RaisedButton(
            onPressed: () => Navigator.pop(context),child: Text('Dismiss'),)
        ],);
  }

  @override
  Widget buildTransitions(
      BuildContext context,Widget child) {
    // You can add your own animations for the overlay content
    return FadeTransition(
      opacity: animation,child: ScaleTransition(
        scale: animation,child: child,);
  }
}


// Example application:
void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Playground',home: TestPage(),);
  }
}

class TestPage extends StatelessWidget {
  void _showOverlay(BuildContext context) {
    Navigator.of(context).push(TutorialOverlay());
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Test')),body: Padding(
        padding: EdgeInsets.all(16.0),child: Center(
          child: RaisedButton(
            onPressed: () => _showOverlay(context),child: Text('Show Overlay'),);
  }
}