Solved

VS2008 Thread to update label

Posted on 2009-05-08
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Last Modified: 2012-08-13
Why does this not work?

    Private Sub UpdateLabel(ByVal [text] As String, ByVal lbl As Label)
        Try
            If lbl.InvokeRequired Then
                Dim d As New LabelCallBack(AddressOf UpdateLabel)
                Me.Invoke(d, New Object() {[text]})
            Else
                lbl.Text = [text]
            End If
        Catch ex As Exception

        End Try
    End Sub

If I specify the label name, everything is fine.
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Comment
Question by:ddepuemd
  • 2
  • 2
5 Comments
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 500 total points
ID: 24335034
Your LabelCallBack is pointing to the same function, which has a signature of (String, Label). However, in your Invoke() method, you are only passing the string. Have you tried passing the label as well?
0
 
LVL 48

Expert Comment

by:jpaulino
ID: 24335171
You need to use Delegates to upate UI controls.
Check some examples that Idle_Mind have posted using threads, backgroundworkers, etc.
http://www.experts-exchange.com/Programming/Languages/.NET/Visual_Basic.NET/Q_24295878.html 
0
 

Author Comment

by:ddepuemd
ID: 24335173
Do you mean like this:

   Private Sub UpdateLabel(ByVal [text] As String, ByVal lbl As Label)
        Try
            If lbl.InvokeRequired Then
                Dim d As New LabelCallBack(AddressOf UpdateLabel)
                Me.Invoke(d, New Object() {[text]}, lbl)
            Else
                lbl.Text = [text]
            End If
        Catch ex As Exception

        End Try
    End Sub

That doesn't work either, the label doesn't update...
0
 
LVL 48

Expert Comment

by:jpaulino
ID: 24335177
Opps! I read it wrong.
What you are trying to do ?
0
 

Author Comment

by:ddepuemd
ID: 24335238
You were right kaufmed, this does work!!  

Private Sub UpdateLabel(ByVal [text] As String, ByVal lbl As Label)
        Try
            If lbl.InvokeRequired Then
                Dim d As New LabelCallBack(AddressOf UpdateLabel)
                Me.Invoke(d, New Object() {[text], lbl})
            Else
                lbl.Text = [text]
            End If
        Catch ex As Exception

        End Try
    End Sub
0

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