.NET MAUI TwoPaneView layout

Artikel
08/30/2024

The TwoPaneView class represents a container with two views that size and position content in the available space, either side-by-side or top-to-bottom. TwoPaneView inherits from Grid so the easiest way to think about these properties is as if they are being applied to a grid.

Surface Duo dual-screen emulator showing a basic TwoPaneView test app

The layout control is provided by the Microsoft.Maui.Controls.Foldable NuGet package.

Foldable device support overview

Foldable devices include the Microsoft Surface Duo and Android devices from other manufacturers. They bridge the gap between phones and larger screens like tablets and desktops because apps might need to adjust to a variety of screen sizes and orientations on the same device, including adapting to a hinge or fold in the screen.

Visit the dual-screen developer docs for more information about building apps that target foldable devices, including design patterns and user experiences. There is also a Surface Duo emulator you can download for Windows, Mac, and Linux.

Important

The TwoPaneView control only adapts to Android foldable devices that support the Jetpack Window Manager API provided by Google (such as Microsoft Surface Duo).

On all other platforms and devices (i.e. other Android devices, iOS, macOS, Windows) it acts like a configurable and responsive split view that can dynamically show one or two panes, proportionally sized on the screen.

Add and configure the Foldable support NuGet

Open the NuGet Package Manager dialog for your solution.
Under the Browse tab, search for Microsoft.Maui.Controls.Foldable.
Install the Microsoft.Maui.Controls.Foldable package to your solution.
Add the UseFoldable() initialization method (and namespace) call to the project's MauiApp class, in the CreateMauiApp method:
```
using Microsoft.Maui.Foldable; // ADD THIS NAMESPACE
...
public static MauiApp CreateMauiApp()
{
    var builder = MauiApp.CreateBuilder();
    ...
    builder.UseFoldable(); // ADD THIS LINE TO THE TEMPLATE
    return builder.Build();
}
```
The UseFoldable() initialization is required for the app to be able to detect changes in the app's state, such as being spanned across a fold.
Update the [Activity(...)] attribute on the MainActivity class in Platforms/Android, so that it includes all these ConfigurationChanges options:
```
ConfigurationChanges = ConfigChanges.Orientation | ConfigChanges.ScreenSize
    | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize | ConfigChanges.UiMode
```
These values are required so that configuration changes and span state can be more reliably reported for reliable dual-screen support.

Set up TwoPaneView

To add the TwoPaneView layout to your page:

Add a foldable namespace alias for the Foldable NuGet:

xmlns:foldable="clr-namespace:Microsoft.Maui.Controls.Foldable;assembly=Microsoft.Maui.Controls.Foldable"

Add the TwoPaneView as the root element on the page, and add controls to Pane1 and Pane2:

<foldable:TwoPaneView x:Name="twoPaneView">
    <foldable:TwoPaneView.Pane1
        BackgroundColor="#dddddd">
        <Label
            Text="Hello, .NET MAUI!"
            SemanticProperties.HeadingLevel="Level1"
            FontSize="32"
            HorizontalOptions="Center" />
    </foldable:TwoPaneView.Pane1>
    <foldable:TwoPaneView.Pane2>
        <StackLayout BackgroundColor="{AppThemeBinding Light={StaticResource Secondary}, Dark={StaticResource Primary}}">
            <Label Text="Pane2 StackLayout"/>
        </StackLayout>
    </foldable:TwoPaneView.Pane2>
</foldable:TwoPaneView>

Understand TwoPaneView modes

Only one of these modes can be active:

SinglePane only one pane is currently visible.
Wide the two panes are laid out horizontally. One pane is on the left and the other is on the right. When on two screens this is the mode when the device is portrait.
Tall the two panes are laid out vertically. One pane is on top and the other is on bottom. When on two screens this is the mode when the device is landscape.

Control TwoPaneView when it's only on one screen

The following properties apply when the TwoPaneView is occupying a single screen:

MinTallModeHeight indicates the minimum height the control must be to enter Tall mode.
MinWideModeWidth indicates the minimum width the control must be to enter Wide mode.
Pane1Length sets the width of Pane1 in Wide mode, the height of Pane1 in Tall mode, and has no effect in SinglePane mode.
Pane2Length sets the width of Pane2 in Wide mode, the height of Pane2 in Tall mode, and has no effect in SinglePane mode.

Important

If the TwoPaneView is spanned across a hinge or fold these properties have no effect.

Properties that apply when on one screen or two

The following properties apply when the TwoPaneView is occupying a single screen or two screens:

TallModeConfiguration indicates, when in Tall mode, the Top/Bottom arrangement or if you only want a single pane visible as defined by the TwoPaneViewPriority.
WideModeConfiguration indicates, when in Wide mode, the Left/Right arrangement or if you only want a single pane visible as defined by the TwoPaneViewPriority.
PanePriority determines whether to show Pane1 or Pane2 if in SinglePane mode.

Troubleshooting

If the TwoPaneView layout isn't working as expected, double-check the set-up instructions on this page. Omitting or misconfiguring the UseFoldable() method or the ConfigurationChanges attribute values are common causes of errors.

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