แก้ไข

แชร์ผ่าน

DoWorkEventHandler Delegate

  • Reference

Definition

Namespace:
System.ComponentModel
Assemblies:
System.dll, System.ComponentModel.EventBasedAsync.dll
Assembly:
System.ComponentModel.EventBasedAsync.dll
Assembly:
System.dll
Assembly:
netstandard.dll

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

public delegate void DoWorkEventHandler(System::Object ^ sender, DoWorkEventArgs ^ e);
public delegate void DoWorkEventHandler(object sender, DoWorkEventArgs e);
public delegate void DoWorkEventHandler(object? sender, DoWorkEventArgs e);
type DoWorkEventHandler = delegate of obj * DoWorkEventArgs -> unit
Public Delegate Sub DoWorkEventHandler(sender As Object, e As DoWorkEventArgs)

Parameters

sender
Object

The source of the event.

e
DoWorkEventArgs

A DoWorkEventArgs that contains the event data.

Examples

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 void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    // Do not access the form's BackgroundWorker reference directly.
    // Instead, use the reference provided by the sender parameter.
    BackgroundWorker bw = sender as BackgroundWorker;

    // Extract the argument.
    int arg = (int)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)
    {
        e.Cancel = true;
    }
}

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

Remarks

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 Handling and Raising Events.

Extension Methods

GetMethodInfo(Delegate)

Gets an object that represents the method represented by the specified delegate.

Applies to

See also