Thread problems

Forgive me if I sound a bit stupid

I am using the DotNetBar componant 'SuperTab' which is basically a tab control
(Not really relevent but Im setting the scene)

I have 5 seperate 'Subs' that create a tab and display a crystalreportviewer

These are working great individually, but when I run all 5 on the form load, it obviously takes a few seconds for everything to run.

So... I thought I would have a go at my first 'threat' and see if I can get all 5 to run symultaniously.

Im using seperate Backgroundworkers, and for each one the 'RunWorkerAsync calls the individual Subs to get all 5 to run

I am hitting across the error
'Control accessed from a thread other than the thread it was created on.'
when each worker is called

Ive done some googling, and tried a number things but I cannot get it to work.

The one that seemed the most successful was:

Code:

---

Private Sub CreateInvoiceOnlyTab()

        If Me.InvokeRequired Then
            Me.Invoke(New MethodInvoker(AddressOf CreateInvoiceOnlyTab))
        Else

'Rest of the Sub code goes here

---

But when that runs it tells me it cant call a disposed object.

So now Im stuck

This is the code without any threading elements:

Code:

---

Private Sub CreateInvoiceOnlyTab()

        Dim newTab As SuperTabItem = SuperTabControl1.CreateTab("Standard Invoice")
        Dim panel As SuperTabControlPanel = DirectCast(newTab.AttachedControl, SuperTabControlPanel)
        Dim crviewer As New CrystalReportViewer
     
        panel.Controls.Add(crviewer)
        crviewer.Dock = DockStyle.Fill
        crviewer.ToolPanelView = ToolPanelViewType.None

        'Generate Report
        Dim report As DaMtechInvoice = New DaMtechInvoice
        Dim crParameterDiscreteValue As ParameterDiscreteValue
        Dim crParameterFieldDefinitions As ParameterFieldDefinitions
        Dim crParameterFieldLocation As ParameterFieldDefinition
        Dim crParameterValues As ParameterValues

        '
        ' Get the report parameters collection.
        '
        'crystalreportspartsviewer()
        crParameterFieldDefinitions = report.DataDefinition.ParameterFields

        ' Add a parameter value - START
        crParameterFieldLocation = crParameterFieldDefinitions.Item("PARAM1")
        crParameterValues = crParameterFieldLocation.CurrentValues
        crParameterDiscreteValue = New CrystalDecisions.Shared.ParameterDiscreteValue
        crParameterDiscreteValue.Value = InvoiceID
        crParameterValues.Add(crParameterDiscreteValue)
        crParameterFieldLocation.ApplyCurrentValues(crParameterValues)
        ' Add a parameter value - END

        crParameterFieldLocation = crParameterFieldDefinitions.Item("PARAM2")
        crParameterValues = crParameterFieldLocation.CurrentValues
        crParameterDiscreteValue = New CrystalDecisions.Shared.ParameterDiscreteValue
        crParameterDiscreteValue.Value = InvoiceID
        crParameterValues.Add(crParameterDiscreteValue)
        crParameterFieldLocation.ApplyCurrentValues(crParameterValues)

        crParameterFieldLocation = crParameterFieldDefinitions.Item("PARAM3")
        crParameterValues = crParameterFieldLocation.CurrentValues
        crParameterDiscreteValue = New CrystalDecisions.Shared.ParameterDiscreteValue
        crParameterDiscreteValue.Value = ClientID
        crParameterValues.Add(crParameterDiscreteValue)
        crParameterFieldLocation.ApplyCurrentValues(crParameterValues)

        crviewer.ReportSource = report
       
    End Sub

---

This code runs perfectly when called as a normal sub

Thanks in advance

Matt

You aren't supposed to do any UI based stuff in a background worker. The BGW runs on its own thread, so you can't work with stuff on the UI thread. Instead you are supposed to use the ProgressChanged and RunWorkerCompleted events, which fire on the UI thread, to make UI changes and updates as the BG worker progresses through its background work.

MSDN explicitly states:

Quote:

---

You must be careful not to manipulate any user-interface objects in your DoWork event handler. Instead, communicate to the user interface through the ProgressChanged and RunWorkerCompleted events.

---

You are trying to work with controls in your thread: if you are working with controls, do it on the main (UI) thread that the controls are created on. If it takes time, determine where the time is being taken: is it retrieving data?

I haven't worked with crystal reports for some time, but way back when, it was a heavy control which doesn't (didn't?) render very quickly. It looks like, though, you may be able to 'create' parts of the component (report) in a thread, then pass those parts back to the main thread and add to the viewer.