import 'package:qrcode_reader/qrcode_reader.dart';

Future<String> futureString = new QRCodeReader()
               .setAutoFocusIntervalInMs(200) // default 5000
               .setForceAutoFocus(true) // default false
               .setTorchEnabled(true) // default false
               .setHandlePermissions(true) // default true
               .setExecuteAfterPermissionGranted(true) // default true
               .setFrontCamera(false) // default false
               .scan();

Future<String> futureString = new QRCodeReader().scan();