Manually adding drag-and-drop support

To support drag-and-drop operations with non-list-based components, or to explicitly control drag and drop with list-based controls, you must handle the drag and drop events.

Classes used in drag-and-drop operations

You use the following classes to implement the drag-and-drop operation:

Class	Function
DragManager	Manages the drag-and-drop operations; for example, its doDrag() method starts the drag operation.
DragSource	Contains the data being dragged. It also provides additional drag management features, such as the ability to add a handler that is called when data is requested.
DragEvent	Represents the event object for all drag-and-drop events.

A component that acts as a drag initiator handles the following events to manage the drag-and-drop operation:

mouseDown and mouseMove,

dragStart

dragComplete.

The mouseDown event is dispatched when the user selects a control with the mouse and holds down the mouse button. The mouseMove event is dispatched when the mouse moves.

dragStart event is Dispatched by a list-based component when a drag operation starts. This event is used internally by the list-based controls; you do not handle it when implementing drag and drop.

dragComplete event is dispatched when a drag operation completes, either when the drag data drops onto a drop target, or when the drag-and-drop operation ends without performing a drop operation.

You can use this event to perform any final cleanup of the drag-and-drop operation.

When adding drag-and-drop support to a component, you must implement an event handler for either the mouseDown or mouseMove event, and optionally for the dragComplete event. When you set the dragEnabled property to true for a list-based control, Flex automatically adds event handlers for the dragStart and dragComplete events.

Drag-and-drop events for a drop target

To use a component as a drop target, you handle the following events:

dragEnter event :

Dispatched when a drag proxy moves over the drop target from outside the drop target.

A component must define an event handler for this event to be a drop target. The event handler determines whether the data being dragged is in an accepted format. To accept the drop, the event handler calls the DragManager.acceptDragDrop() method. You must call the DragManager.acceptDragDrop() method for the drop target to receive the dragOver, dragExit, and dragDrop events.

In the handler, you can change the appearance of the drop target to provide visual feedback to the user that the component can accept the drag operation. For example, you can draw a border around the drop target, or give focus to the drop target.

dragOver event is :

Dispatched while the user moves the mouse over the target, after the dragEnter event.

You can handle this event to perform additional logic before allowing the drop operation, such as dropping data to various locations within the drop target, reading keyboard input to determine if the drag-and-drop operation is a move or copy of the drag data, or providing different types of visual feedback based on the type of drag-and-drop operation.

dragDrop event is dispatched when the user releases the mouse over the drop target.

dragExit event is dispatched

when the user moves the drag proxy off of the drop target, but does not drop the data onto the target.

You can use this event to restore the drop target to its normal appearance if you modified its appearance in response to a dragEnter event or other event.

When adding drag-and-drop support to a nonlist-based component, you must implement an event handler for the dragEnter and dragDrop events, and optionally for the other events.