Update the UI based on orientation
In some situations, you want to update the display of an app when the user rotates the screen from portrait mode to landscape mode. For example, the app might show one item after the next in portrait mode, yet put those same items side-by-side in landscape mode.
In Flutter, you can build different layouts depending on a given Orientation
. In this example, build a list that displays two columns in portrait mode and three columns in landscape mode using the following steps:
- Build a
GridView
with two columns. - Use an
OrientationBuilder
to change the number of columns.
1. Build a GridView
with two columns
#First, create a list of items to work with. Rather than using a normal list, create a list that displays items in a grid. For now, create a grid with two columns.
return GridView.count(
// A list with 2 columns
crossAxisCount: 2,
// ...
);
To learn more about working with GridViews
, see the Creating a grid list recipe.
2. Use an OrientationBuilder
to change the number of columns
#To determine the app's current Orientation
, use the OrientationBuilder
widget. The OrientationBuilder
calculates the current Orientation
by comparing the width and height available to the parent widget, and rebuilds when the size of the parent changes.
Using the Orientation
, build a list that displays two columns in portrait mode, or three columns in landscape mode.
body: OrientationBuilder(
builder: (context, orientation) {
return GridView.count(
// Create a grid with 2 columns in portrait mode,
// or 3 columns in landscape mode.
crossAxisCount: orientation == Orientation.portrait ? 2 : 3,
);
},
),
Interactive example
#import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
const appTitle = 'Orientation Demo';
return const MaterialApp(
title: appTitle,
home: OrientationList(
title: appTitle,
),
);
}
}
class OrientationList extends StatelessWidget {
final String title;
const OrientationList({super.key, required this.title});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text(title)),
body: OrientationBuilder(
builder: (context, orientation) {
return GridView.count(
// Create a grid with 2 columns in portrait mode, or 3 columns in
// landscape mode.
crossAxisCount: orientation == Orientation.portrait ? 2 : 3,
// Generate 100 widgets that display their index in the List.
children: List.generate(100, (index) {
return Center(
child: Text(
'Item $index',
style: Theme.of(context).textTheme.displayLarge,
),
);
}),
);
},
),
);
}
}
Locking device orientation
#In the previous section, you learned how to adapt the app UI to device orientation changes.
Flutter also allows you to specify the orientations your app supports using the values of DeviceOrientation
. You can either:
- Lock the app to a single orientation, like only the
portraitUp
position, or... - Allow multiple orientations, like both
portraitUp
andportraitDown
, but not landscape.
In the application main()
method, call SystemChrome.setPreferredOrientations()
with the list of preferred orientations that your app supports.
To lock the device to a single orientation, you can pass a list with a single item.
For a list of all the possible values, check out DeviceOrientation
.
void main() {
WidgetsFlutterBinding.ensureInitialized();
SystemChrome.setPreferredOrientations([
DeviceOrientation.portraitUp,
]);
runApp(const MyApp());
}
Unless stated otherwise, the documentation on this site reflects the latest stable version of Flutter. Page last updated on 2024-06-26. View source or report an issue.