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POMultithreading for a progressbar and code locations (vb.net)?
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copied!<p>I am stuck updating a progressbar from a different thread. I did get it running in the simplest way, but then cleaning the code gets me stuck.</p> <p>My testing code looks like all the examples on the web related to backgroundworker and BeginInvoke.</p> <p>FormP is the Progressbar-Form. This works:</p> <pre><code>Public Class Form1 Private Delegate Sub delegate_ProgressUpdate(ByVal paramValue As Integer, ByVal paramMax As Integer) Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click ' Test 01: ' Show Progressbar via BGW ' All functions are within Form1 Dim bgw As New BackgroundWorker() AddHandler bgw.DoWork, AddressOf BGW_Sample01_DoWork FormP.Show(Me) bgw.RunWorkerAsync() End Sub Private Sub invokeMe_ProgressUpdate(ByVal paramValue As Integer, ByVal paramMax As Integer) FormP.ProgressBar1.Maximum = paramMax FormP.ProgressBar1.Value = paramValue FormP.ProgressBar1.Update() End Sub Private Sub BGW_Sample01_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) For i As Integer = 1 To 10 Threading.Thread.Sleep(500) ' Test delay Me.BeginInvoke(New delegate_ProgressUpdate(AddressOf invokeMe_ProgressUpdate), i, 10) Next MessageBox.Show("Fertig") End Sub </code></pre> <p>If I try to make things work more orderly encapsulated in FormP, it doesn't work.</p> <pre><code>Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click Dim bgw As New BackgroundWorker AddHandler bgw.DoWork, AddressOf BGW_Sample02_DoWork FormP.Show(Me) bgw.RunWorkerAsync() End Sub Private Sub BGW_Sample02_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) For i As Integer = 1 To 10 Threading.Thread.Sleep(500) FormP.SetProgress(i, 10) Next MessageBox.Show("Fertig") End Sub ' ########## FormP ################# Public Class FormP Private Delegate Sub delegate_ProgressUpdate(ByVal value As Integer, ByVal maximum As Integer) Public Sub SetProgress(ByVal paramValue As Integer, ByVal paramMaximum As Integer) If Me.InvokeRequired Then Me.Invoke(New delegate_ProgressUpdate(AddressOf Me.SetProgress), paramValue, paramMaximum) Else Me.ProgressBar1.Maximum = paramMaximum Me.ProgressBar1.Value = paramValue Me.ProgressBar1.Update() End If End Sub End Class </code></pre> <p>FormP does not freeze, but UI is not updated. Actually Me.InvokeRequired is false and I think that's where I begin to miss some important parts. I tried Form1.InvokeRequired here, but it's false as well. My understanding is: the calling thread here is the bgw thread, no matter in what class the code is that this thread calls... That seems not to be it?</p> <p>Thanks for any thoughts.</p>

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