Window doesn't maximize in WinUI3

Question

I am using the following code to start a WinUI3 App maximized:

    public MainWindow()
    {
        this.InitializeComponent();
        var windowHandle = WinRT.Interop.WindowNative.GetWindowHandle(this);
        var windowId = Win32Interop.GetWindowIdFromWindow(windowHandle);
        AppWindow appWindow = AppWindow.GetFromWindowId(windowId);
        OverlappedPresenter presenter = (OverlappedPresenter)appWindow.Presenter;
        presenter.Maximize();
        Debug.WriteLine(presenter.State);
    }

There are no errors, debug output reports the OverlappedPresenter state as Maximized, but the window stays in the restored state.

Any suggestions are welcome, thanks in advance.

Hireling

Answer 1

Try putting Maximize() in App's OnLaunched method:

    protected override void OnLaunched(LaunchActivatedEventArgs args)
    {
        ...
        presenter.Maximize();
    }

Or the Window's OnActivated event:

    private void OnActivated(object sender, WindowActivatedEventArgs args)
    {
        ...
        presenter.Maximize();
    }

Urgent

Using it in OnLaunched, solved my problem. Thanks! – Hireling

Answer 2

var hWnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
        Microsoft.UI.WindowId windowId = Microsoft.UI.Win32Interop.GetWindowIdFromWindow(hWnd);
        Microsoft.UI.Windowing.AppWindow appWindow = Microsoft.UI.Windowing.AppWindow.GetFromWindowId(windowId);

        if (appWindow != null )
        {
            OverlappedPresenter op = appWindow.Presenter as OverlappedPresenter;
            op.Maximize();
        }

Token

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. – Gulp