BackgroundWorker.OnProgressChanged Method

Raises the ProgressChanged event.

Namespace:  System.ComponentModel
Assembly:  System (in System.dll)

protected virtual void OnProgressChanged(
	ProgressChangedEventArgs e
)

Parameters

e
Type: System.ComponentModel.ProgressChangedEventArgs

An EventArgs that contains the event data.

Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.

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 in a derived class, be sure to call the base class's OnProgressChanged method so that registered delegates receive the event.

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);
    }
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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