WPF: Close a secondary window when application shutdown without "programmer" intervention

It's quite hard to explain this in the title, if someone would like to change it it's ok.

I have a situation where, in WPF, I create an "hidden" window which is transparent to the programmer. What I mean is that this window is created in static constructor, hidden and moved outside of the screen and it's width and height are 0. This because I'm using this window to do some interop operations and to allow a sort of handlers for all WndProcs override that someone could require (there is a list of delegates which handles methods that should override WndProc).

In hope that you understand what I've said (it's not easy), my problem is that when I create a WPF project and start it, if I close the Main Window (which is not the one created transparently to the programmer), I want that my application shutdown. However with the code I created this doesn't happen except if I use Application.Current.Shutdown();

Are there any way to fix this without calling that method? I want a transparent way, that other programmers shouldn't even notice (it's a lib, shouldn't change the behaviour of working programs in this way).

Thanks for any suggestion, here you can see some code snippets:

The window created by the lib

public class InteropWindow : Window
{
    public HwndSource Source { get; protected set; }

    private static InteropWindow _Instance;

    static InteropWindow()
    {
        _WndProcs = new LinkedList<WndProcHandler>();
        _Instance = new InteropWindow();
    }

    private static WindowInteropHelper _InteropHelper;
    public static WindowInteropHelper InteropHelper
    {
        get
        {
            if (_InteropHelper == null)
            {
                _InteropHelper = new WindowInteropHelper(_Instance);
                _InteropHelper.EnsureHandle();
            }
            return _InteropHelper;
        }
    }

    public static IntPtr Handle { get { return InteropHelper.Handle; } }

    private InteropWindow()
    {
        Opacity = 0.0;
        //We have to "show" the window in order to obtain hwnd to process WndProc messages in WPF
        Top = -10;
        Left = -10;
        Width = 0;
        Height = 0;
        WindowStyle = WindowStyle.None;
        ShowInTaskbar = false;
        ShowActivated = false;
        Show();
        Hide();
    }

    private static LinkedList<WndProcHandler> _WndProcs;
    public static void AddWndProcHandler(WndProcHandler handler)
    {
        _WndProcs.AddLast(handler);
    }
    public static void RemoveWndProcHandler(WndProcHandler handler)
    {
        _WndProcs.Remove(handler);
    }

    private static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        IntPtr result = IntPtr.Zero;
        foreach (WndProcHandler handler in _WndProcs)
        {
            IntPtr tmp = handler(hwnd, msg, wParam, lParam, ref handled);
            if (tmp != IntPtr.Zero)
            {
                if (result != IntPtr.Zero)
                    throw new InvalidOperationException(string.Format("result should be zero if tmp is non-zero:\nresult: {0}\ntmp: {1}", result.ToInt64().ToString(), tmp.ToInt64().ToString()));
                result = tmp;
            }
        }
        return result;
    }

    protected override void OnSourceInitialized(EventArgs e)
    {
        base.OnSourceInitialized(e);
        Source = PresentationSource.FromVisual(this) as HwndSource;
        Source.AddHook(WndProc);
        OnWindowInitialized(null, e);
    }

    protected override void OnClosed(EventArgs e)
    {
        base.OnClosed(e);
        if (Source != null)
            Source.RemoveHook(WndProc);
        OnWindowClosed(null, e);
    }

    private static void OnWindowInitialized(object sender, EventArgs e)
    {
        if (WindowInitialized != null) WindowInitialized(sender, e);
    }

    private static void OnWindowClosed(object sender, EventArgs e)
    {
        if (WindowClosed != null) WindowClosed(sender, e);
    }

    public static event EventHandler WindowInitialized;

    public static event EventHandler WindowClosed;
}

A normal window created with wpf (base window created from project)

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        ExClipboard.ClipboardUpdate += new RoutedEventHandler(ExClipboard_ClipboardUpdate);
        Closed += new EventHandler(MainWindow_Closed);
    }

    private void MainWindow_Closed(object sender, EventArgs e)
    {
        //InteropWindow.Dispose();
        App.Current.Shutdown(0);
    }
}

Update 开发者_如何转开发1:

To answer to your answers, No I would like to avoid any intervetion by programmer using my library, so the ideal solution is that in my lib I subscribe to some Application.Exit event and close my window, obviusly I can't use Application.Exit because the application doesn't close due of my window not closing

Maybe there is a way to calculate all windows that belongs to an application? I can do something with that too

---

If you have a main window, can't you set Application.ShutdownMode to OnMainWindowClose ?

The default value is OnLastWindowClose, which is most likely why you're seeing this behaviour.

---

It's a cheap hack, but I think this may achieve what you're after..

In your lib you will need to reference the xaml dependencies (PresentationCore, PresentationFramework, System.Xaml and WindowsBase)

In the static constructor for your lib, you can then add something like

Application.Current.MainWindow.Closed += new EventHandler(MainWindow_Closed);

static void MainWindow_Closed(object sender, EventArgs e)
{
    Dispose();
}

Where dispose closes your window (_Instance.Close()) and handles any other clean-up calls

---

Conceptually speaking, the only thing that comes to mind is an event message notification service, in which, the second window is listening or awaiting a message to close and the first window sends a message for it to be closed. This also requires using the MVVM pattern. I'm not sure about this entirely, and I am also not sure if this falls into your idea of not letting other programmers know.

Here is a blog article on it: Sending notifications in WPF MVVM applications