How to make UWP AppWindow enter full screen mode?

Question

I'm using AppWindow to create multiple windows for the app, and I want the user to be able to make the windows full screen, but ApplicationView.TryEnterFullScreenMode doesn't work, it returns false all the time when used in an AppWindow.

Sample code from Microsoft Docs:

private void ToggleFullScreenModeButton_Click(object sender, RoutedEventArgs e)
{
    var view = ApplicationView.GetForCurrentView();
    if (view.IsFullScreenMode)
    {
        view.ExitFullScreenMode();
    }
    else
    {
        view.TryEnterFullScreenMode(); // Returns false in an AppWindow
    }
}

How do you make an AppWindow enter full screen mode?

Answer 1

For AppWindow you should use AppWindowPresenter.RequestPresentation and pass AppWindowPresentationKind.FullScreen as parameter.

The solution I came up with (based on this answer) handles exiting full screen mode using:

• The original button.
• The back to window button in the title bar.
• The escape key.

XAML:

<Button x:Name="ToggleFullScreenButton" Text="Full screen mode" Click="ToggleFullScreenButton_Click" />

Code behind:

public AppWindow AppWindow { get; } // This should be set to the AppWindow instance.

private void ToggleFullScreenButton_Click(object sender, RoutedEventArgs e)
{
    var configuration = AppWindow.Presenter.GetConfiguration();
    if (FullScreenButton.Text == "Exit full screen mode" && _tryExitFullScreen())
    {
        // Nothing, _tryExitFullScreen() worked.
    }
    else if (AppWindow.Presenter.RequestPresentation(AppWindowPresentationKind.FullScreen))
    {
        FullScreenButton.Text = "Exit full screen mode";

        _ = Task.Run(async () =>
        {
            await Task.Delay(500); // Delay a bit as AppWindow.Changed gets fired many times on entering full screen mode.
            await Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
            {
                AppWindow.Changed += AppWindow_Changed;
                this.KeyDown += Page_KeyDown;
            });
        });
    }
}

private bool _tryExitFullScreen()
{
    if (AppWindow.Presenter.RequestPresentation(AppWindowPresentationKind.Default))
    {
        FullScreenButton.Text = "Full screen mode";
        AppWindow.Changed -= AppWindow_Changed;
        this.KeyDown -= Page_KeyDown;
        return true;
    }

    return false;
}

// handles the back-to-window button in the title bar
private void AppWindow_Changed(AppWindow sender, AppWindowChangedEventArgs args)
{
    if (args.DidSizeChange) // DidSizeChange seems good enough for this
    {
        _tryExitFullScreen();
    }
}

// To make the escape key exit full screen mode.
private void Page_KeyDown(object sender, KeyRoutedEventArgs e)
{
    if (e.Key == Windows.System.VirtualKey.Escape)
    {
        _tryExitFullScreen();
    }
}