DragEventArgs.Effect Property


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Gets or sets the target drop effect in a drag-and-drop operation.

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

member Effect : DragDropEffects with get, set

Property Value

Type: System.Windows.Forms.DragDropEffects

One of the DragDropEffects values.

By default, the effect applied determines the mouse cursor for the target of a drag-and-drop operation. This is useful to provide feedback to the user on the operation that will occur. For example, if you press the CTRL key when you drag a file from a source, specify DragDropEffects.Copy to indicate the target will try to perform a copy operation.

To use custom cursors for a drag operation, see GiveFeedbackEventArgs.UseDefaultCursors.

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.

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 UseCustomCursorsCheckCheckBox is checked. The custom cursors are set in the GiveFeedback event handler.

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 DropLocationLabelLabel.

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.

This code excerpt demonstrates using the DragEventArgs class. See the DoDragDrop method for the complete code example.

No code example is currently available or this language may not be supported.

.NET Framework
Available since 1.1
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