flutter set orientation
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
void main() {
// We need to call it manually,
// because we going to call setPreferredOrientations()
// before the runApp() call
WidgetsFlutterBinding.ensureInitialized();
// Than we setup preferred orientations,
// and only after it finished we run our app
SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp])
.then((value) => runApp(MyApp()));
}