how to lock screen orientation in flutter code example

Example 1: flutter lock screen to portrait mode

void main() {
// flutter lock screen to portrait mode
  WidgetsFlutterBinding.ensureInitialized();
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown,
  ]);
  runApp(MyBudgetApp());
}

Example 2: flutter lock orientation for page

@override
void initState(){
  super.initState();
  SystemChrome.setPreferredOrientations([
      DeviceOrientation.landscapeRight,
      DeviceOrientation.landscapeLeft,
  ]);
}