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Can not dispatch the function for updating the UI
navraj #1
Member since Dec 2010 · 9 posts
Group memberships: Members
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Subject: WPF Cross thread operation
hello all,

i am creating a messenger application in WPF and i am able to login into Openfire server with both agsxmpp and matrix. i created a login screen with user name and password button  and a login and cancel button.
when it successfully logs in i want to make the cancel and login button invisible but it does not happen and says the calling thread cannot access this object because a different thread owns it.

i have tried using dispatcher but WPF does not have an invoke required function

here is the code

   Private Sub SignIn_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles SignIn.Click
        Dim jid As New Jid(txtID.Text)
        xmppCon.Password = txtPassword.Password
        xmppCon.Username = jid.User
        xmppCon.Server = jid.Server
        xmppCon.AutoAgents = False
        xmppCon.AutoPresence = True
        xmppCon.AutoRoster = True
        xmppCon.AutoResolveConnectServer = True


        Catch ex As Exception

        End Try

    End Sub

    Private Sub xmppCon_OnLogin(ByVal sender As Object) Handles xmppCon.OnLogin
        Dim ob(0) As Object
        ob(0) = sender
        Cancel.Dispatcher.BeginInvoke(CType(AddressOf xmppCon_OnLogin, agsXMPP.ObjectHandler), ob)
 Cancel.Visibility = Windows.Visibility.Hidden

        Debug.Write("lOGGED iN")

    End Sub

can somebody give me an idea how it gets done in WPF?
Alex #2
Member since Feb 2003 · 4434 posts · Location: Germany
Group memberships: Administrators, Members
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When you set a reference to your Ui in the Dispatcher property then MatriX handles all the dispathing for you automatically.
I use rhe following code in my WPF apps:

  1. xmppClient.Dispatcher = this.Dispatcher;

Quote by navraj:
i have tried using dispatcher but WPF does not have an invoke required function

it's Dispatcher.CheckAccess() in WPF. But you don't need it because MatriX does the job for you.

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