Write to textbox.text while running backgroundworker VB.net - vb.net

Question

Hi so i have small form application
the problem was that when i was running tasks on the main thread, the program window wasn't responding
so my button redirects the task to the backgroudworker:
Private Sub btn_start_Click(sender As Object, e As EventArgs) Handles btn_start.Click
BackgroundWorker1.RunWorkerAsync()
End Sub
Now i want to output to my textbox (txtlog) some text from this Backgroudworker multiple time in one Sub. I found a solution that allows this. but this makes the code quite ugly if I have to use it several times:
Example
Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
If txtLog.InvokeRequired Then
txtLog.Invoke(Sub() txtLog.AppendText("My text" & vbNewLine))
txtLog.Invoke(Sub() txtLog.ScrollToCaret())
Else
txtLog.AppendText("My text" & vbNewLine)
txtLog.ScrollToCaret()
End If
Something in Backgroudworker . . .
If txtLog.InvokeRequired Then
txtLog.Invoke(Sub() txtLog.AppendText("My text" & vbNewLine))
txtLog.Invoke(Sub() txtLog.ScrollToCaret())
Else
txtLog.AppendText("My text" & vbNewLine)
txtLog.ScrollToCaret()
End If
. . .
End Sub
Is there any shorter method that would allow me to write in textbox?

Answer 1

The whole point of using a BackgroundWorker is so that you don't have to call Invoke and use delegates. If you're going to do that anyway then the BackgroundWorker is pointless.
With regards to the code you have, what's the point of testing InvokeRequired when you know for a fact that the DoWork event handler will be executed on a background thread? It's always going to be True. Also, why would you call Invoke twice and add all that overhead when you can call it once and do as many things as you like in the one call?
Private Sub BackgroundWorker1_DoWork(sender As Object, e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
txtLog.Invoke(Sub()
txtLog.AppendText("My text" & vbNewLine))
txtLog.ScrollToCaret()
End Sub)
As I said though, you shouldn't be calling Invoke at all. If you want to do something on the UI thread from a BackgroundWorker then you call ReportProgress and handle the ProgressChanged event. The code you want executed goes in the event handler and you call ReportProgress as required. If you need to pass data, you do so using the second argument to ReportProgress and get it back from e.UserState in the event handler. Here's one I prepared earlier:
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'Raise the DoWork event in a worker thread.
Me.BackgroundWorker1.RunWorkerAsync()
End Sub
'This method is executed in a worker thread.
Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, _
ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
Dim worker As System.ComponentModel.BackgroundWorker = DirectCast(sender, System.ComponentModel.BackgroundWorker)
For i As Integer = 1 To 100
'Raise the ProgressChanged event in the UI thread.
worker.ReportProgress(i, i & " iterations complete")
'Perform some time-consuming operation here.
Threading.Thread.Sleep(250)
Next i
End Sub
'This method is executed in the UI thread.
Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As Object, _
ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
Me.ProgressBar1.Value = e.ProgressPercentage
Me.Label1.Text = TryCast(e.UserState, String)
End Sub
'This method is executed in the UI thread.
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, _
ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
Me.Label1.Text = "Operation complete"
End Sub