testing if window is loaded.

gritter

I am writing a WPF app that loops thru a series of windows. The first time thru, I need to create the next window, but on subsequent times, I want it to re-display the previously created window. I believe the function TryFindResource() should help me do this, but it's not working. See code below.

Private Sub btnGo_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)

    Dim nextWindow As Window = CType(TryFindResource("Window3"), Window)
    If (nextWindow Is Nothing) Then
        nextWindow = New Window3
        nextWindow.Show()
    Else
        nextWindow.Show()
    End If

End Sub

Appreciate any help with this. Yes, this is my first WPF app.

gritter

I changed the line with TryFindResource() to:

Dim nextWindow As Window = CType(Application.Current.TryFindResource("Window3"), Window)

The change made no difference. It still doesn't find the existing instance of Window3.

Ian Shlasko

Try a static/shared field - These are related to the class itself, not to the instance of the class: In the Window3 code:

Private Shared _currentInstance as Window3

Public Shared Function GetInstance() As Window3
If _currentInstance Is Nothing Then
_currentInstance = New Window3
End If

GetInstance = _currentInstance
End Function

Also, be sure to add code to the OnClosing, or some similar location, to set _currentInstance back to Nothing if you close Window3. And in your btnGo code:

Window3.GetInstance().Show()

Oh, and might want to consider giving Window3 a more meaningful name.

Proud to have finally moved to the A-Ark. Which one are you in? Author of Guardians of Xen (Sci-Fi/Fantasy novel)

gritter

Thanks! That works, except it does shift focus to the "called window". If you can help me out here too, I would appreciate it. WPF makes me feel pretty helpless. I didn't realize it was so different from WinForms.

gritter

Actually I think I got. It's probably not the best way, but I can do what I need by playing with the "topmost" property. Thanks.