Question

How do i load the Main form of a WPF so that a seperate thread goes and gets data from the database while the form is in an apartmentstate ? (drag-able / movable)

I Know this is possible with opening a new window from your main form like this :

Private Sub openOrderWindow()
    Dim OrderWindow As Orders = New Orders
    OrderWindow.ShowDialog()
End Sub

Private Sub ButtonImport_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles ButtonImport.Click
    Dim iThread As System.Threading.Thread = New System.Threading.Thread(AddressOf openOrderWindow)
    iThread.SetApartmentState(System.Threading.ApartmentState.STA)
    iThread.Start()
    ListViewOrderDetail.Focus()
    ' Me.Close()
End Sub

because i use ‘ShowDialog’

But on the main window i can’t call ShowDialog

What i have Tried:

 Private Sub AccessDBFilling()
ListViewDataGrid.ItemsSource = Nothing
    accessdblist = Nothing
accessdblist = accessdb.GetFromAccess()
ListViewDataGrid.ItemsSource = accessdblist
End Sub

 Private Sub refresh()
    ListViewDataGrid.Dispatcher.Invoke(New Action(AddressOf AccessDBFilling))
End Sub

Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
    iThread = New System.Threading.Thread(AddressOf refresh)
    iThread.SetApartmentState(System.Threading.ApartmentState.STA)
    iThread.Start()
End Sub

---

I’ve tried putting MyBase.ShowDialog() and .Show() and .9000+ other things

The only benefit I’ve got out of using a seperate thread to load from the databse is i can see the screen right away (as oppose to it being a transparent box until it loads) but i cannot move it around or minimize it

is there any way to make it Movable while it loads?

Answer 1

Yes. You should understand what you did.

ListViewDataGrid.Dispatcher.Invoke(New Action(AddressOf AccessDBFilling))

The dispatcher of the UI Controls is correspond to the UI thread. so the UI is freezed, because you load data exactly on UI thread.

Here what you should to do:

Private Sub AccessDBFilling()
    ListViewDataGrid.ItemsSource = Nothing
    accessdblist = Nothing
    accessdblist = accessdb.GetFromAccess()
    //I'm not sure, but you can try the following lines of code. uncomment one of them.

    //ListViewDataGrid.Dispatcher.Invoke(() => ListViewDataGrid.ItemsSource = accessdblist);
    //ListViewDataGrid.ItemsSource = accessdblist;
End Sub

Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
    Action loadFromDb = AccessDBFilling;
    loadFromDb.BeginInvoke();
End Sub

As I’m don’t know VB, you should translate it from C# 🙂