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Drag-and-Drop Functionality in Windows Forms

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Windows Forms includes a set of methods, events, and classes that implement drag-and-drop behavior. This topic provides an overview of the drag-and-drop support in Windows Forms. Also see Drag-and-Drop Operations and Clipboard Support.

Performing Drag-and-Drop Operations

To perform a drag-and-drop operation, use the DoDragDrop method of the Control class. For more information about how a drag-and-drop operation is performed, see DoDragDrop. To get the rectangle that the mouse pointer must be dragged over before a drag-and-drop operation begins, use the DragSize property of the SystemInformation class.

There are two categories of events in a drag and drop operation: events that occur on the current target of the drag-and-drop operation, and events that occur on the source of the drag and drop operation.

Events on the Current Target

The following table shows the events that occur on the current target of a drag-and-drop operation.

Mouse Event Description
DragEnter This event occurs when an object is dragged into the control's bounds. The handler for this event receives an argument of type DragEventArgs.
DragOver This event occurs when an object is dragged while the mouse pointer is within the control's bounds. The handler for this event receives an argument of type DragEventArgs.
DragDrop This event occurs when a drag-and-drop operation is completed. The handler for this event receives an argument of type DragEventArgs.
DragLeave This event occurs when an object is dragged out of the control's bounds. The handler for this event receives an argument of type EventArgs.

The DragEventArgs class provides the location of the mouse pointer, the current state of the mouse buttons and modifier keys of the keyboard, the data being dragged, and DragDropEffects values that specify the operations allowed by the source of the drag event and the target drop effect for the operation.

Events on the Source

The following table shows the events that occur on the source of the drag-and-drop operation.

Mouse Event Description
GiveFeedback This event occurs during a drag operation. It provides an opportunity to give a visual cue to the user that the drag-and-drop operation is occurring, such as changing the mouse pointer. The handler for this event receives an argument of type GiveFeedbackEventArgs.
QueryContinueDrag This event is raised during a drag-and-drop operation and enables the drag source to determine whether the drag-and-drop operation should be canceled. The handler for this event receives an argument of type QueryContinueDragEventArgs.

The QueryContinueDragEventArgs class provides the current state of the mouse buttons and modifier keys of the keyboard, a value specifying whether the ESC key was pressed, and a DragAction value that can be set to specify whether the drag-and-drop operation should continue.

See also