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[Flutter] Decide Whether The Screen Maintains A Vertical Or Horizontal

In the process of developing an App, we may need to maintain the vertical or horizontal screen orientation of user’s device to different needs; or, when the App can switch between different functions automatically rotation.

Of course we can implement these operations in Flutter. In below, I will simply record how to manipulate the direction of the screen.

Initial setting & button setting

We can set the fixed screen orientation during the App startup phase, it can also used to set only vertical or horizontal layout.

It’s a simple example as follows:

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

// Main
void main() {
  SystemChrome.setPreferredOrientations([
    // Orientations
    // DeviceOrientation.landscapeLeft,
    // DeviceOrientation.landscapeRight,
    DeviceOrientation.portraitDown,
    DeviceOrientation.portraitUp,
  ]);

  runApp(MyApp());
}

// MyApp
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

// HomePage
class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

// _HomePageState
class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        Container(
          width: 200,
          height: 100,
          color: Colors.red,
        ),
        RaisedButton(
            child: Text("Portrait"),
            onPressed: () {
              setState(() {
                SystemChrome.setPreferredOrientations([
                  DeviceOrientation.landscapeLeft,
                ]);
              });
            })
      ],
    );
  }
}


Output:


Change single page

If you just need to set the single page, you can set the initial orientation or change orientation function in the initState() and dispose() of the page.

@override
void initState() {
  super.initState();

  // Init
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.landscapeRight,
    DeviceOrientation.landscapeLeft,
  ]);
}

@override
void dispose() {

  // Change
  SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown,
  ]);

  super.dispose();
}


References

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