Progress Bar - Threading - Minimizing Window

[timmeh_041]

Hey guys,

Now I know what I am about to describe is generally considered bad practice, so just bare with me as I describe it.

Part of my application deals with creating a number of pivot tables. I pull data from a local database, and store it in a datatable. From here, the data is processed and eventually a pivot table is returned. On small data sets it works well, but on some larger one there is a few seconds of "nothing" until the table is shown.

After a few iterations of trying things to display some form of progress I have ended up with a form with nothing but a progress bar running on it. I spawn a new thread, and run it. It works exactly like I hoped. However, when I call the thread.abort() method to terminate the thread, occasionally, the main form will minimize. I tired having me.show() aftre the .abort() to bring the form into view again, but it appears not to have helped.

Now I understand that it is better practice to have worker background threads, and the main thread for UI, but is there a simple way of ensuring that the main form does not close?

    Private Sub LoadProgressForm()
        Dim progressForm As New ProgressBar
        progressForm.ShowDialog()
    End Sub

   Private Sub DoButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ViewButton.Click

            Dim t As New Thread(AddressOf LoadProgressForm)
            t.Start()
            'code that does stuff to do with pivoting

            t.abort()
            me.show()

   End Sub

Thanks

[jmcilhinney]

You shouldn't be showing the progress dialogue on the secondary thread. You should be showing the dialogue on the UI thread and then doing the processing on the secondary thread.

[timmeh_041]

Yeah I know. I was just trying to take the lazy mans way and avoid having to rewrite alot of things. The pivottable function takes in a number of parameters, and it is my understanding I can not simply pass these through to the thread.

In order to change it up in that manner, I have to put the function into its own class, correct? So the parameters are variables within that class, and have the function as one of the classes functions? How would I go about returning a value (ie. a datatable) from the secondary thread once it has been completed?

Do you recommend any good links/tuts to read? I read a couple simple ones, but I am not really sure what I am looking for to do what I need done.

Thanks