BackgroundWorker.OnProgressChanged(ProgressChangedEventArgs) Method
Definition
Important
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Raises the ProgressChanged event.
protected:
virtual void OnProgressChanged(System::ComponentModel::ProgressChangedEventArgs ^ e);protected virtual void OnProgressChanged (System.ComponentModel.ProgressChangedEventArgs e);abstract member OnProgressChanged : System.ComponentModel.ProgressChangedEventArgs -> unit
override this.OnProgressChanged : System.ComponentModel.ProgressChangedEventArgs -> unitProtected Overridable Sub OnProgressChanged (e As ProgressChangedEventArgs)Parameters
An EventArgs that contains the event data.
Examples
The following code example demonstrates the use of the OnProgressChanged method to report the progress of an asynchronous operation. This code example is part of a larger example provided for the AsyncOperationManager class.
// This method is invoked via the AsyncOperation object,
// so it is guaranteed to be executed on the correct thread.
private void CalculateCompleted(object operationState)
{
CalculatePrimeCompletedEventArgs e =
operationState as CalculatePrimeCompletedEventArgs;
OnCalculatePrimeCompleted(e);
}
// This method is invoked via the AsyncOperation object,
// so it is guaranteed to be executed on the correct thread.
private void ReportProgress(object state)
{
ProgressChangedEventArgs e =
state as ProgressChangedEventArgs;
OnProgressChanged(e);
}
protected void OnCalculatePrimeCompleted(
CalculatePrimeCompletedEventArgs e)
{
if (CalculatePrimeCompleted != null)
{
CalculatePrimeCompleted(this, e);
}
}
protected void OnProgressChanged(ProgressChangedEventArgs e)
{
if (ProgressChanged != null)
{
ProgressChanged(e);
}
}
' This method is invoked via the AsyncOperation object,
' so it is guaranteed to be executed on the correct thread.
Private Sub CalculateCompleted(ByVal operationState As Object)
Dim e As CalculatePrimeCompletedEventArgs = operationState
OnCalculatePrimeCompleted(e)
End Sub
' This method is invoked via the AsyncOperation object,
' so it is guaranteed to be executed on the correct thread.
Private Sub ReportProgress(ByVal state As Object)
Dim e As ProgressChangedEventArgs = state
OnProgressChanged(e)
End Sub
Protected Sub OnCalculatePrimeCompleted( _
ByVal e As CalculatePrimeCompletedEventArgs)
RaiseEvent CalculatePrimeCompleted(Me, e)
End Sub
Protected Sub OnProgressChanged( _
ByVal e As ProgressChangedEventArgs)
RaiseEvent ProgressChanged(e)
End Sub
Remarks
Raising an event invokes the event handler through a delegate. For more information, see Handling and Raising Events.
The OnProgressChanged method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.
Notes to Inheritors
When overriding OnProgressChanged(ProgressChangedEventArgs) in a derived class, be sure to call the base class's OnProgressChanged(ProgressChangedEventArgs) method so that registered delegates receive the event.
