How to take a screenshot of the current widget - Flutter

I tried and found the solution,

import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:ui' as ui;
import 'package:flutter/rendering.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:io';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});
  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static GlobalKey previewContainer = GlobalKey();
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {

    return RepaintBoundary(
        key: previewContainer,
      child: Scaffold(
      appBar: AppBar(

        title: Text(widget.title),
      ),
      body: Center(
        child: Column(

          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
            ElevatedButton(
                onPressed: takeScreenShot,
              child: const Text('Take a Screenshot'),
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    )
    );
  }
  Future<void> takeScreenShot() async{
    final boundary = previewContainer.currentContext!.findRenderObject() as RenderRepaintBoundary;
    final image = await boundary.toImage();
    final directory = (await getApplicationDocumentsDirectory()).path;
    final byteData = await image.toByteData(format: ui.ImageByteFormat.png);
    final pngBytes = byteData?.buffer.asUint8List();
    final imgFile =File('$directory/screenshot.png');
    imgFile.writeAsBytes(pngBytes!);
  }
}

Finally check your application directory You will find screenshot.png !!

let's say you want to take a screenshot of the FlutterLogo widget . wrap it in a RepaintBoundary with will creates a separate display list for its child . and provide with a key

var scr= new GlobalKey();
RepaintBoundary(
         key: scr,
         child: new FlutterLogo(size: 50.0,))

and then you can get the pngBytes by converting the boundary to an image

takescrshot() async {
  RenderRepaintBoundary boundary = scr.currentContext.findRenderObject();
  var image = await boundary.toImage();
  var byteData = await image.toByteData(format: ImageByteFormat.png);
  var pngBytes = byteData.buffer.asUint8List();
  print(pngBytes);
  }

here's the solution for flutter 2.0+ method for screenshot and share it on social media

 import 'package:flutter/rendering.dart';
        import 'package:flutter/services.dart';
        import 'dart:ui' as ui;
        import 'package:path_provider/path_provider.dart';
        import 'package:share/share.dart';
        
        GlobalKey previewContainer = new GlobalKey();
    
     @override
      Widget build(BuildContext context) {
        return Scaffold(
          appBar: AppBar(
            // Here we take the value from the MyHomePage object that was created by
            // the App.build method, and use it to set our appbar title.
            title: Text(widget.title),
          ),
          body: RepaintBoundary(
            key: previewContainer,
            child: Center(
              // Center is a layout widget. It takes a single child and positions it
              // in the middle of the parent.
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  Text(
                    'Take Screen Shot',
                  ),
                ],
              ),
            ),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: _captureSocialPng,
            tooltip: 'Increment',
            child: Icon(Icons.camera),
          ), // This trailing comma makes auto-formatting nicer for build methods.
        );
      }
    
        
          Future<void> _captureSocialPng() {
            List<String> imagePaths = [];
            final RenderBox box = context.findRenderObject() as RenderBox;
            return new Future.delayed(const Duration(milliseconds: 20), () async {
              RenderRepaintBoundary? boundary = previewContainer.currentContext!
                  .findRenderObject() as RenderRepaintBoundary?;
              ui.Image image = await boundary!.toImage();
              final directory = (await getApplicationDocumentsDirectory()).path;
              ByteData? byteData =
                  await image.toByteData(format: ui.ImageByteFormat.png);
              Uint8List pngBytes = byteData!.buffer.asUint8List();
              File imgFile = new File('$directory/screenshot.png');
              imagePaths.add(imgFile.path);
              imgFile.writeAsBytes(pngBytes).then((value) async {
                await Share.shareFiles(imagePaths,
                    subject: 'Share',
                    text: 'Check this Out!',
                    sharePositionOrigin: box.localToGlobal(Offset.zero) & box.size);
              }).catchError((onError) {
                print(onError);
              });
            });
          }

Run

flutter screenshot

It will take the screenshot from your connected device and save that to your folder in which you are doing development it will save flutter_01.jpg like that in your folder