Question: I'm not seeing the Closing event in the Window component.

[germanfortiz]

Testing Project Reunion 0.5, I'm not able to stop the closing of my application because there is not a Closing event. May be i'm missing something or is just this Window event is not yet available?

<Window
    x:Class="WinUI3Desktop.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:WinUI3Desktop"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Activated="Window_Activated"
    Closing="Window_Closing"  <--- Not available
    Closed="Window_Closed"
    VisibilityChanged="Window_VisibilityChanged"
    mc:Ignorable="d">

[marb2000]

The event is not available in WinUI 3, but you can implement it by yourself using the Win32 APIs. For example: https://github.com/marb2000/DesktopWindow

[germanfortiz]

Thank you for the tip.! Just curious, in future WinUI3 Window implementations, we will have to implement this event as an extension, as you suggested?

[pushkin-]

@marb2000 do you have thoughts on germanfortiz's question above. I'm moving a WPF app to WinUI3 and I'm missing this Closing event that WPF had. Can we expect one in the future?

[dimohy]

@marb2000

Thanks for writing the DesktopWindow extension code.

WinUI 3 is now 1.0.2 and there is still no Closing event.

So, referring to DesktopWindow, I tried to intercept the window message and implement the close event directly, but there is a problem in the basic structure.

(It works normally in Packaged.)

When unpackaged, it does not work with the following exception.

The code below is the reproduced code. https://github.com/dimohy/csharp-check/tree/main/WinUI3/WinUI3UnpackagedWinProcTest

If you are still working on this and know the cause, please help.

[jamers99]

Definitally would like to see this implemented!

[castorix]

There is AppWindow.Closing Event

[germanfortiz]

But not Window.Closing... Window Events

[castorix]

But not Window.Closing... Window Events

It is the same thing : you can intercept it to prevent closing

[yvlawy]

Thanks for the solution, it works fine!

In App.OnLaunched() add: m_window.Closed += Window_Closed;

in Window_Closed(object sender, WindowEventArgs args) to stop the closing of the window do:
args.Handled = true;

-Exit the application from a window or a page: Application.Current.Exit(); will execute the Window_Closed callback.

[github-actions[bot]]

This issue is stale because it has been open 180 days with no activity. Remove stale label or comment or this will be closed in 5 days.

[germanfortiz]

With the help of @castorix and @yvlawy, I finally solved this issue:

In the App.OnLaunched event, I added this:

  protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
  {
        mainWindow = new MainWindow()
        {
            Title = this.GetVersionDescription(),
        };

        mainWindow.Activate();

        // Get the handle of the created window.
        this.windowhandle = PInvoke.User32.GetActiveWindow();

        // Retrieve the WindowId that corresponds to hWnd.
        Microsoft.UI.WindowId windowId =
            Microsoft.UI.Win32Interop.GetWindowIdFromWindow(this.windowhandle);

        // Lastly, retrieve the AppWindow for the current (XAML) WinUI 3 window.
        Microsoft.UI.Windowing.AppWindow appWindow =
            Microsoft.UI.Windowing.AppWindow.GetFromWindowId(windowId);

        if (appWindow != null)
        {
            appWindow.Closing += this.AppWindow_Closing;
        }
  }

Finally, to stop the closing event, I added the following in the AppWindow_Closing function:

  private void AppWindow_Closing(Microsoft.UI.Windowing.AppWindow sender, Microsoft.UI.Windowing.AppWindowClosingEventArgs args)
  {
        if (somethingIsRunningAndTheUserCanNotCloseTheApp())
        {
              args.Cancel = true; // This prevents the application to close.
        }
  }

Thanks!