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| /** | |
| * Drag and Drop is a direct manipulation gesture found in many Graphical User | |
| * Interface systems that provides a mechanism to transfer information between | |
| * two entities logically associated with presentation elements in the GUI. | |
| * Normally driven by a physical gesture of a human user using an appropriate | |
| * input device, Drag and Drop provides both a mechanism to enable continuous | |
| * feedback regarding the possible outcome of any subsequent data transfer to | |
| * the user during navigation over the presentation elements in the GUI, and the | |
| * facilities to provide for any subsequent data negotiation and transfer. | |
| * <p> | |
| * This package defines the classes and interfaces necessary to perform Drag and | |
| * Drop operations in Java. It defines classes for the drag-source and the | |
| * drop-target, as well as events for transferring the data being dragged. This | |
| * package also provides a means for giving visual feedback to the user | |
| * throughout the duration of the Drag and Drop operation. | |
| * <p> | |
| * A typical Drag and Drop operation can be decomposed into the following states | |
| * (not entirely sequentially): | |
| * <ul> | |
| * <li>A {@code DragSource} comes into existence, associated with some | |
| * presentation element ({@code Component}) in the GUI, to initiate a Drag | |
| * and Drop of some potentially {@code Transferable} data.</li> | |
| * <li>1 or more {@code DropTarget}(s) come into/go out of existence, | |
| * associated with presentation elements in the GUI (Components), | |
| * potentially capable of consuming {@code Transferable} data types.</li> | |
| * <li>A {@code DragGestureRecognizer} is obtained from the | |
| * {@code DragSource} and is associated with a {@code Component} in order to | |
| * track and identify any Drag initiating gesture by the user over the | |
| * {@code Component}.</li> | |
| * <li>A user makes a Drag gesture over the {@code Component}, which the | |
| * registered {@code DragGestureRecognizer} detects, and notifies its | |
| * {@code DragGestureListener} of. | |
| * <p> | |
| * Note: Although this API consistently refers to the stimulus for a drag | |
| * and drop operation being a physical gesture by a human user, this does | |
| * not preclude a programmatically driven DnD operation given the | |
| * appropriate implementation of a {@code DragSource}. This package | |
| * contains the abstract class {@code MouseDragGestureRecognizer} for | |
| * recognizing mouse device gestures. Other abstract subclasses may be | |
| * provided by the platform to support other input devices or particular | |
| * {@code Component} class semantics.</li> | |
| * <li>The {@code DragGestureListener} causes the {@code DragSource} to | |
| * initiate the Drag and Drop operation on behalf of the user, perhaps | |
| * animating the GUI Cursor and/or rendering an {@code Image} of the item(s) | |
| * that are the subject of the operation.</li> | |
| * <li>As the user gestures navigate over {@code Component}(s) in the GUI | |
| * with associated {@code DropTarget}(s), the {@code DragSource} receives | |
| * notifications in order to provide "Drag Over" feedback effects, and the | |
| * {@code DropTarget}(s) receive notifications in order to provide | |
| * "Drag Under" feedback effects based upon the operation(s) supported and | |
| * the data type(s) involved.</li> | |
| * </ul> | |
| * <p> | |
| * The gesture itself moves a logical cursor across the GUI hierarchy, | |
| * intersecting the geometry of GUI Component(s), possibly resulting in the | |
| * logical "Drag" cursor entering, crossing, and subsequently leaving | |
| * {@code Component}(s) and associated {@code DropTarget}(s). | |
| * <p> | |
| * The {@code DragSource} object manifests "Drag Over" feedback to the user, in | |
| * the typical case by animating the GUI {@code Cursor} associated with the | |
| * logical cursor. | |
| * <p> | |
| * {@code DropTarget} objects manifest "Drag Under" feedback to the user, in the | |
| * typical case, by rendering animations into their associated GUI | |
| * {@code Component}(s) under the GUI Cursor. | |
| * <p> | |
| * The determination of the feedback effects, and the ultimate success or | |
| * failure of the data transfer, should one occur, is parameterized as follows: | |
| * <ul> | |
| * <li>By the transfer "operation" selected by the user, and supported by | |
| * both the {@code DragSource} and {@code DropTarget}: Copy, Move or | |
| * Reference(link).</li> | |
| * <li>By the intersection of the set of data types provided by the | |
| * {@code DragSource} and the set of data types comprehensible by the | |
| * {@code DropTarget}.</li> | |
| * <li>When the user terminates the drag operation, normally resulting in a | |
| * successful Drop, both the {@code DragSource} and {@code DropTarget} | |
| * receive notifications that include, and result in the type negotiation | |
| * and transfer of, the information associated with the {@code DragSource} | |
| * via a {@code Transferable} object.</li> | |
| * </ul> | |
| * | |
| * @since 1.2 | |
| */ | |
| package java.awt.dnd; |