Hello,


I am writing a program that assigns data sources to crystal report documents and assigns them to crystal report viewer on a Windows form. To make the UI responsive I chose to implement this inside new threads. My Sub does some database binding and then assigns the datasource to the crystal viewer which is naturally running in the UI main thread.

As usual, I had to use delegates and invoke. What I am doing is that I am checking whether the viewer is invoked before modifying its data source.


Please find below my code:


Now my problem is that I noticed that every time an invoke is performed the SUB is called again and so doing the same job twice. This applies on modification that I might want to do on CrystalViewer. Is there a way to avoid this? Thanks

Yes! Just Call CheckForIllegalCrossThreadCalls before asking if invoke is required an don't use it

Private Sub ShowAllInternationalCalls()



Dim myDoc as New CrystalDecisions.CrystalReports.Engine.ReportDocument
MyDoc= New rpt_rated_allcalls()

EmpTableAdapter.FillBy_All_Employees(Me.DataSet.Employees)

rptDoc.SetDataSource(DataSet)

CheckForIllegalCrossThreadCalls = False

CrystalViewer.ReportSource = rptDoc


End Sub

If you prefer to do it the way you want (checking if invoke is required)

then refactor this part of code

If CrystalViewer.InvokeRequired Then

Dim newDelegate As New UIDelegate(AddressOf ShowAllInternationalCalls)
CrystalViewer.Invoke(newDelegate)

Else

CrystalViewer.ReportSource = rptDoc

End If

to a new method.

Yeah you are right. I agree that this might not be safe when working with multi-threading. Anyway, I figured that I should include all the code that I want to run once in the ELSE section after checking for CrystalView control IsInvoked event. I believe this is the best technique, what do you think.

Regards..