c# - open wpf from winform throws object reference not set to an instance of

Question

I have a WPF custom control and I needs to open it from WinForm. I have followed all steps mentioned in http://weblogs.asp.net/jdanforth/open-a-wpf-window-from-winforms and Open WPF window in WindowsForm APP

But still it gives me an object reference not set to an instance of exceptions.

Winform:

private void button1_Click(object sender, EventArgs e)
        {
            var notificatioinapp = new WpfCustomControlLibrary1.Window1();
            ElementHost.EnableModelessKeyboardInterop(notificatioinapp);
            notificatioinapp.Show();
        }

WPF custom control:

public partial class Window1 : Window
    {
        public Window1() : base()
        {
            InitializeComponent();
            this.Closed += this.NotificationWindowClosed;
        }
    public new void Show()
    {
        this.Topmost = true;
        base.Show();

        this.Owner = System.Windows.Application.Current.MainWindow;
        this.Closed += this.NotificationWindowClosed;
        var workingArea = Screen.PrimaryScreen.WorkingArea;

        this.Left = workingArea.Right - this.ActualWidth;
        double top = workingArea.Bottom - this.ActualHeight;

        foreach (Window window in System.Windows.Application.Current.Windows)
        {
            string windowName = window.GetType().Name;

            if (windowName.Equals("NotificationWindow") && window != this)
            {
                window.Topmost = true;
                top = window.Top - window.ActualHeight;
            }
        }

        this.Top = top;
    }
    private void ImageMouseUp(object sender,
        System.Windows.Input.MouseButtonEventArgs e)
    {
        this.Close();
    }

    private void DoubleAnimationCompleted(object sender, EventArgs e)
    {
        if (!this.IsMouseOver)
        {
            this.Close();
        }
    }

    private void NotificationWindowClosed(object sender, EventArgs e)
    {
        foreach (Window window in System.Windows.Application.Current.Windows)
        {
            string windowName = window.GetType().Name;

            if (windowName.Equals("NotificationWindow") && window != this)
            {
                // Adjust any windows that were above this one to drop down
                if (window.Top < this.Top)
                {
                    window.Top = window.Top + this.ActualHeight;
                }
            }
        }
    }
}

Appreciate any support.

Answer 1

Application.Current is Specific for WPF Application actually. So I think since you are trying to open WPF application from WinForms Application you need to initialize instance of WPF Application first before accessing it.

if ( null == System.Windows.Application.Current )
{
   new System.Windows.Application();
}

If this doesn't work try setting Application.Current.MainWindow = this; in loaded event of WPF window.

This should do the fix.

EDIT :

private void button1_Click(object sender, EventArgs e)
{

    if (null == System.Windows.Application.Current)
    {
        new System.Windows.Application();
    }

    var wpfwindow = new Window();
    wpfwindow = new WpfCustomControlLibrary1.Window1();
    ElementHost.EnableModelessKeyboardInterop(wpfwindow);
    wpfwindow.Show();

}