flutter---->flutter orientation

Get the orientation

1. Media Query

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text("child"), centerTitle: true),
        body: MainWidget(),
      ),
    );
  }
}

class MainWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final Orientation orientation = MediaQuery.of(context).orientation;
    return orientation == Orientation.portrait
        ? Container( 100, height: 100, child: Text("portrait"))
        : Container( 100, height: 100, child: Text("landscape"));
  }
}

2. Orientation Builder

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text("child"), centerTitle: true),
        body: OrientationBuilder(
          builder: (context, orientation) {
            return orientation == Orientation.portrait
                ? Container( 100, height: 100, child: Text("portrait"))
                : Container( 100, height: 100, child: Text("landscape"));
          },
        ),
      ),
    );
  }
}

3. Layout Builder

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text("child"), centerTitle: true),
        body: LayoutBuilder(
          builder: (context, constraints) {
            final bool isPortrait = constraints.maxHeight > constraints.maxWidth;
            return isPortrait
                ? Container( 100, height: 100, child: Text("portrait"))
                : Container( 100, height: 100, child: Text("landscape"));
          },
        ),
      ),
    );
  }
}

Change Orientation

First, you have to import the services package.

import 'package:flutter/services.dart';

Next, you can set orientation by setting the value to setPreferredOrientations method in SystemChrome class. In the Flutter the application entry point is the main method. So you can set orientation before call the runApp method in the main method. But if you need to call a binding before the runApp method, you must call the ensureInitialized method in WidgetsFlutterBinding class

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await SystemChrome.setPreferredOrientations([DeviceOrientation.landscapeLeft]);
  runApp(MyApp());
}

Set landscape orientation only

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

You can set either landscapeLeft or landscapeRight to make it work in one way.

Set portrait orientation only

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

If you set both portraitUp and portraitDown as orientation when you tilt your phone upside down it will rotate the app. If you don’t like to work in upside-down orientation, you can just set only the portraitUp.

Change orientation dynamically

RaisedButton(
  child: Text("Portrait"),
  onPressed: () => SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp]),
);