Question

I need to report progress changed. Consider the following code:

Public Class Calculator   Public Event CalculationProgress (ByVal sender As Object, ByVal e As MyCalculationProgressEventArgs) Public Function Calculate(..).. ' Perform calculation here ... ' Reporting proggress Dim args As New MyCalculationProgressEventArgs(myobj, myValue)   RaiseEvent CalculationProgress (Me, args) ... End Class 

*** Another class

Private WithEvents calculator As Calculator  Private Function PerformCalculation(ByVal obj As Object) As CalcParams Dim params As CalcParams = CType(obj, CalcParams) calculator = GetCalculator() .... Return params.result = calculator.Calculate End Function  Private Sub calculationWorker_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) _ Handles calculationWorker.DoWork   Dim calcResult As MyType = PerformCalculation(CType(e.Argument, MyType ))   e.Result = calcResult End Sub  Private Sub calculationWorker_ProgressChanged(ByVal sender As Object, ByVal e As ProgressChangedEventArgs) _ Handles calculationWorker.ProgressChanged      CType(Parent.Parent, MainWindow).pbcCurrentProgress.Value = e.ProgressPercentage End Sub 

How and where should I subscribe to CalculationProgress event to call

 calculationWorker.ReportProgress(MyCalculationProgressEventArgs.Percent) 

?

Answer 1

Are you using a BackgroundWorker object here? If so what you want to do is to subscribe to the CalculationProgress event inside of the calculationWorker_DoWork event handler. You didn’t post any information on MyType, so I’ll assume you’ll need to alter my code to get the Calculator instance.

Private Sub calculationWorker_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) _   Handles calculationWorker.DoWork      Dim calcResult As MyType = PerformCalculation(CType(e.Argument, MyType ))     Dim calc = calcResult.Calculator   AddHandler calc.CalculationProgress, AddressOf HandleCalculationProgress   ...   RemoveHandler calc.CalculationProgress, AddressOf HandleCalculationProgress   e.Result = calcResult End Sub