How can we set device brightness using flutter?

Question

By using the screen brightness or screen package I am able to change the screen brightness of the mobile phone but the changed brightness is not reflected in the device brightness slider and the mobile adjusts to device brightness after coming out of the application.

Is there a way to write the brightness of the mobile phone using flutter?

Answer 1

We will use Screen package dependency and add to pubspec.yaml file

screen: ^2.5.0

Add the wakelock permission in AndroidManifest.xml file

<uses-permission android:name="android.permission.WAKE_LOCK"/>

Now your main.dart file be like:

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(
         home: HomePage(),
    );
  }
}

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

class _HomePageState extends State<HomePage> {

  double screenbrightness = 0.5;
  //brightness must be double value rainding 0.0 - 1.0

// Get the current brightness:
double brightness = await Screen.brightness;

// Set the brightness:
Screen.setBrightness(0.5);

// Check if the screen is kept on:
bool isKeptOn = await Screen.isKeptOn;

// Prevent screen from going into sleep mode:
Screen.keepOn(true);

  @override
  void initState() {

    Future.delayed(Duration.zero,() async { //there is await function, so we use Future.delayed
        double brightness = await Screen.brightness; //get the current screen brightness
        if(brightness > 1){
           brightness = brightness / 10; 
           // sometime it gives value ranging 0.0 - 10.0, so convert it to range 0.0 - 1.0
        }
        print(brightness);
        setState(() {
            screenbrightness = brightness;
            //change the variable value and update screen UI

        });
    });
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        backgroundColor: Colors.blue[100], //background color of scaffold
        appBar: AppBar(
            title:Text("Change Screen Brightness"), //title of app
            backgroundColor: Colors.redAccent, //background color of app bar
        ),
        body: Container(
          child:Column(children: [
               Container( 
                 margin: EdgeInsets.only(top:60),
                 child: Text("Chnage Screen Brightness")
               ),
               Container( 
                 child: Text("Brightness Value: $screenbrightness")
               ),
               Container( 
                 child: Slider( //add the slider to configure brightness
                   min: 0.0,
                   max: 1.0,
                    onChanged: (value){ //this function will be executed when slider value is changed
                      Screen.setBrightness(value); //set screen brightness with slider value
                      setState(() {
                        screenbrightness = value; //update the UI
                      }); 
                    }, 
                    value: screenbrightness, //set default slider value
                 )
               )
          ],)
        )
     );
  }
}