How To Create Screen Brightness Using Flutter Android App

dependencies:
  flutter:
    sdk: flutter
  screen: ^0.0.5

flutter pub get

import 'package:screen/screen.dart';

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:screen/screen.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.green,
      ),
      home: MyHomePage(),
      debugShowCheckedModeBanner: false,
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
  @override
  bool _isKeptOn = false;
  double _brightness = 1.0;

  @override
  initState() {
    super.initState();
    initPlatformState();
  }

  initPlatformState() async {
    bool keptOn = await Screen.isKeptOn;
    double brightness = await Screen.brightness;
    setState((){
      _isKeptOn = keptOn;
      _brightness = brightness;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(
          backgroundColor: Colors.lightGreen,
            title: new Text('Screen Brightness'
            )),
        body: new Center(
            child: new Column(
              mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  new Text("Brightness :",style: TextStyle(fontSize:15, fontWeight: FontWeight.bold),),
                  new Slider(value : _brightness,
                      activeColor: Colors.lightGreen,
                      onChanged : (double b){
                    setState((){_brightness = b;});
                    Screen.setBrightness(b);
                  })
                ]
            )
        ),
    );
  }
}