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GiveFeedbackEventHandler Delegate

Represents the method that handles the GiveFeedback event of a Control.

[Visual Basic]
<Serializable>
Public Delegate Sub GiveFeedbackEventHandler( _
   ByVal sender As Object, _
   ByVal e As GiveFeedbackEventArgs _
)
[C#]
[Serializable]
public delegate void GiveFeedbackEventHandler(
   object sender,
   GiveFeedbackEventArgs e
);
[C++]
[Serializable]
public __gc __delegate void GiveFeedbackEventHandler(
   Object* sender,
   GiveFeedbackEventArgs* e
);

[JScript] In JScript, you can use the delegates in the .NET Framework, but you cannot define your own.

Parameters [Visual Basic, C#, C++]

The declaration of your event handler must have the same parameters as the GiveFeedbackEventHandler delegate declaration.

sender
The source of the event.
e
A GiveFeedbackEventArgs that contains the event data.

Remarks

When you create a GiveFeedbackEventHandler 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 is called whenever the event occurs, unless you remove the delegate. For more information about handling events with delegates, see Events and Delegates.

Example

[Visual Basic, C#, C++] The following example demonstrates a drag-and-drop operation between two ListBox controls. The example calls the DoDragDrop method when the drag action starts. The drag action starts if the mouse has moved more than SystemInformation.DragSize from the mouse location during the MouseDown event. The IndexFromPoint method is used to determine the index of the item to drag during the MouseDown event.

[Visual Basic, C#, C++] The example also demonstrates using custom cursors for the drag-and-drop operation. The example assumes that two cursor files, 3dwarro.cur and 3dwno.cur, exist in the application directory, for the custom drag and no-drop cursors, respectively. The custom cursors will be used if the UseCustomCursorsCheck CheckBox is checked. The custom cursors are set in the GiveFeedback event handler.

[Visual Basic, C#, C++] The keyboard state is evaluated in the DragOver event handler for the right ListBox, to determine what the drag operation will be based upon state of the SHIFT, CTRL, ALT, or CTRL+ALT keys. The location in the ListBox where the drop would occur is also determined during the DragOver event. If the data to drop is not a String, then the DragEventArgs.Effect is set to DragDropEffects.None. Finally, the status of the drop is displayed in the DropLocationLabel Label.

[Visual Basic, C#, C++] The data to drop for the right ListBox is determined in the DragDrop event handler and the String value is added at the appropriate place in the ListBox. If the drag operation moves outside the bounds of the form, then the drag-and-drop operation is canceled in the QueryContinueDrag event handler.

[Visual Basic, C#, C++] This code excerpt demonstrates using the GiveFeedbackEventHandler delegate with the GiveFeedback event. See the DoDragDrop method for the complete code example.

[Visual Basic] 
Private Sub ListDragSource_GiveFeedback(ByVal sender As Object, ByVal e As GiveFeedbackEventArgs) Handles ListDragSource.GiveFeedback

    ' Use custom cursors if the check box is checked.
    If (UseCustomCursorsCheck.Checked) Then

        ' Set the custom cursor based upon the effect.
        e.UseDefaultCursors = False
        If ((e.Effect And DragDropEffects.Move) = DragDropEffects.Move) Then
            Cursor.Current = MyNormalCursor
        Else
            Cursor.Current = MyNoDropCursor
        End If
    End If

End Sub

[C#] 
private void ListDragSource_GiveFeedback(object sender, System.Windows.Forms.GiveFeedbackEventArgs e) 
{
    // Use custom cursors if the check box is checked.
    if (UseCustomCursorsCheck.Checked) {

        // Sets the custom cursor based upon the effect.
        e.UseDefaultCursors = false;
        if ((e.Effect & DragDropEffects.Move) == DragDropEffects.Move)
            Cursor.Current = MyNormalCursor;
        else 
            Cursor.Current = MyNoDropCursor;
    }

}

[C++] 
private:
   void ListDragSource_GiveFeedback(Object* /*sender*/, 
      System::Windows::Forms::GiveFeedbackEventArgs* e)
   {

      // Use custom cursors if the check box is checked.
      if (UseCustomCursorsCheck->Checked) {

         // Sets the custom cursor based upon the effect.
         e->UseDefaultCursors = false;
         if ((e->Effect & DragDropEffects::Move) == DragDropEffects::Move)
            Cursor::Current = MyNormalCursor;
         else
            Cursor::Current = MyNoDropCursor;
      }

   }

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Windows.Forms

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: System.Windows.Forms (in System.Windows.Forms.dll)

See Also

System.Windows.Forms Namespace | OnGiveFeedback | GiveFeedback | GiveFeedbackEventArgs

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