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DoWorkEventHandler Delegate

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

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

<HostProtectionAttribute(SecurityAction.LinkDemand, SharedState := True)> _
Public Delegate Sub DoWorkEventHandler ( _
	sender As Object, _
	e As DoWorkEventArgs _
Dim instance As New DoWorkEventHandler(AddressOf HandlerMethod)


Type: System.Object

The source of the event.

Type: System.ComponentModel.DoWorkEventArgs

A DoWorkEventArgs that contains the event data.


The HostProtectionAttribute attribute applied to this type or member 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.

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 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 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0