DoWorkEventHandler Delegate

Represents the method that will handle the DoWork event. This class cannot be inherited.

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

Public Delegate Sub DoWorkEventHandler ( _
	sender As Object, _
	e As DoWorkEventArgs _
Dim instance As New DoWorkEventHandler(AddressOf HandlerMethod)
/** @delegate */
public delegate void DoWorkEventHandler (
	Object sender, 
	DoWorkEventArgs e
Not applicable.



The source of the event.


A DoWorkEventArgs that contains the event data.

When you create a DoWorkEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event-handler method is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.


The HostProtectionAttribute attribute applied to this class has the following Resources property value: SharedState. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following code example demonstrates how to use the DoWorkEventHandler delegate to handle the DoWork event. For a full code listing, see How to: Run an Operation in the Background.

Private Sub backgroundWorker1_DoWork( _
sender As Object, e As DoWorkEventArgs) _
Handles backgroundWorker1.DoWork

   ' Do not access the form's BackgroundWorker reference directly.
   ' Instead, use the reference provided by the sender parameter.
   Dim bw As BackgroundWorker = CType( sender, BackgroundWorker )
   ' Extract the argument.
   Dim arg As Integer = Fix(e.Argument)
   ' Start the time-consuming operation.
   e.Result = TimeConsumingOperation(bw, arg)
   ' If the operation was canceled by the user, 
   ' set the DoWorkEventArgs.Cancel property to true.
   If bw.CancellationPending Then
      e.Cancel = True
   End If

End Sub   

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0