Marquee Progress Bar with Background Worker in VB.NET - vb.net

Question

I have a main form with a progressbar at the bottom status strip. It is set to marquee style. I want it to keep animating when
I run a long function. But when the function hits, the form and everything on it freezes, so II used a backgroundworker
to run the long function. But this gave me the following error inside the MyClass.BigFunction() code.
Cross-thread operation not valid: Control 'frmMainNew' accessed from a thread other than the thread it was created on.
"frmMainNew" is the main form on which the progressbar and backgroundworker are. I pass the form as a parameter to the MyClass object
when I initialize it.
This is the first time I am using backgroundworker, so what else do I need?
I have already looked at these examples and tried them, but nothing works. (1, 2, 3, 4, 5, 6).
I have to use this for other functions too.
My code:
Private WithEvents bgw As BackgroundWorker
Private Sub frmMainNew_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Try
Me.SuspendLayout()
'Other Functions
w_AddBackgroundWorkerForProgressBar()
Me.ResumeLayout()
Catch ex As Exception
Scube.Planner.ErrorHandler.DisplayError(ex)
End Try
End Sub
Private Sub w_AddBackgroundWorkerForProgressBar()
bgw = New BackgroundWorker
AddHandler bgw.DoWork, AddressOf bgw_DoWork
AddHandler bgw.RunWorkerCompleted, AddressOf bgw_Completed
'AddHandler bgw.ProgressChanged, AddressOf bgw_ProgressChanged
End Sub
Private Sub MyButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyButton.Click
Try
bgw.WorkerSupportsCancellation = True
bgw.RunWorkerAsync()
'MyClass.BigFunction() <--- Originally called from here
Catch ex As Exception
Scube.Planner.ErrorHandler.DisplayError(ex)
Finally
Me.Cursor = Cursors.Default
End Try
End Sub
Private Sub bgw_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) Handles bgw.DoWork
'Do your lenghty operations here
MyClass.BigFunction()
System.Threading.Thread.Sleep(10000)
End Sub
Private Sub bgw_Completed(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) Handles bgw.RunWorkerCompleted
If Not IsNothing(e.Error) Then
MessageBoxEx.Show(e.Error.ToString)
End If
ProgressBar1.Hide()
End Sub
Private Sub w_ShowProgressBar()
ProgressBar1.Show()
Me.Refresh()
System.Windows.Forms.Application.DoEvents()
End Sub

Answer 1

You cant and should not access your frmMainNew from your 'BigFunction()'. It is working on a separate thread and does not have access to the UI thread. We need to see what you are doing inside your bigfunction to tell you the problem. Im going to take a guess and say you are trying to update the progressbar values from within that function? If this is so then is the incorrect way to do so.
What you need to do is, set the progress in your BigFunction like so:
bgw.ReportProgress(Progress/Percentage)
and have an event for the progress changed and inside of that event is where you update the progress bar.
Private Sub BackgroundWorker1_ProgressChanged(sender As Object, e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
Progressbar1.value = e.ProgressPercentage
End Sub