SimpleDialogBox

import 'package:flutter/material.dart';
import 'dart:ui';
import 'dart:async';
enum Option{A,B,C}
void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  Future dialogBox()async{
    final option=await showDialog(
      context: context,
      builder: (BuildContext context){
        return SimpleDialog(
          title: Text('this is a dialog'),
          children: <Widget>[
            SimpleDialogOption(
              child: Text('option A'),
              onPressed: (){
                Navigator.pop(context,Option.A);
              },
            ),
            SimpleDialogOption(
              child: Text('option B'),
              onPressed: (){
                Navigator.pop(context,Option.B);
              },
            ),
            SimpleDialogOption(
              child: Text('option C'),
              onPressed: (){
                Navigator.pop(context,Option.C);
              },
            ),
          ],
        );
      }
    );
    switch(option){
      case Option.C:
        debugPrint('your choice is C');
        break;
      case Option.A:
        debugPrint('your choice is A');
        break;
      case Option.B:
        debugPrint('your choice is B');
        break;
    }
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        width: window.physicalSize.width,
        height: window.physicalSize.height,
        child: Image.network(
          'http://www.ecobentech.com/img/a.jpg',
          fit: BoxFit.cover,
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed:(){dialogBox();},
        child: Icon(Icons.text_fields),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
    );
  }
}