How to set landscape orientation mode for flutter app?

Enable forcefully

Import package: import 'package:flutter/services.dart'; in main.dart file

1. Landscape mode:

// Set landscape orientation
SystemChrome.setPreferredOrientations([
  DeviceOrientation.landscapeLeft,
  DeviceOrientation.landscapeRight,
]);

2. Portrait mode:

// Set portrait orientation
SystemChrome.setPreferredOrientations([
   DeviceOrientation.portraitDown,
   DeviceOrientation.portraitUp,
]);

import 'package:flutter/services.dart';

void main()  {
   WidgetsFlutterBinding.ensureInitialized();
   SystemChrome.setPreferredOrientations([DeviceOrientation.landscapeLeft])
   .then((_) {
    runApp(new MyApp());
  });
}