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/* * @(#)DropTargetListener.java 1.23 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.awt.dnd; import java.util.EventListener; import java.awt.dnd.DropTargetContext; import java.awt.dnd.DropTargetDragEvent; import java.awt.dnd.DropTargetDropEvent; /** * The <code>DropTargetListener</code> interface * is the callback interface used by the * <code>DropTarget</code> class to provide * notification of DnD operations that involve * the subject <code>DropTarget</code>. Methods of * this interface may be implemented to provide * "drag under" visual feedback to the user throughout * the Drag and Drop operation. * <p> * Create a listener object by implementing the interface and then register it * with a <code>DropTarget</code>. When the drag enters, moves over, or exits * the operable part of the drop site for that <code>DropTarget</code>, when * the drop action changes, and when the drop occurs, the relevant method in * the listener object is invoked, and the <code>DropTargetEvent</code> is * passed to it. * <p> * The operable part of the drop site for the <code>DropTarget</code> is * the part of the associated <code>Component</code>'s geometry that is not * obscured by an overlapping top-level window or by another * <code>Component</code> higher in the Z-order that has an associated active * <code>DropTarget</code>. * <p> * During the drag, the data associated with the current drag operation can be * retrieved by calling <code>getTransferable()</code> on * <code>DropTargetDragEvent</code> instances passed to the listener's * methods. * <p> * Note that <code>getTransferable()</code> on the * <code>DropTargetDragEvent</code> instance should only be called within the * respective listener's method and all the necessary data should be retrieved * from the returned <code>Transferable</code> before that method returns. * * @version 1.23, 11/17/05 * @since 1.2 */ public interface DropTargetListener extends EventListener { /** * Called while a drag operation is ongoing, when the mouse pointer enters * the operable part of the drop site for the <code>DropTarget</code> * registered with this listener. * * @param dtde the <code>DropTargetDragEvent</code> */ void dragEnter(DropTargetDragEvent dtde); /** * Called when a drag operation is ongoing, while the mouse pointer is still * over the operable part of the drop site for the <code>DropTarget</code> * registered with this listener. * * @param dtde the <code>DropTargetDragEvent</code> */ void dragOver(DropTargetDragEvent dtde); /** * Called if the user has modified * the current drop gesture. * <P> * @param dtde the <code>DropTargetDragEvent</code> */ void dropActionChanged(DropTargetDragEvent dtde); /** * Called while a drag operation is ongoing, when the mouse pointer has * exited the operable part of the drop site for the * <code>DropTarget</code> registered with this listener. * * @param dte the <code>DropTargetEvent</code> */ void dragExit(DropTargetEvent dte); /** * Called when the drag operation has terminated with a drop on * the operable part of the drop site for the <code>DropTarget</code> * registered with this listener. * <p> * This method is responsible for undertaking * the transfer of the data associated with the * gesture. The <code>DropTargetDropEvent</code> * provides a means to obtain a <code>Transferable</code> * object that represents the data object(s) to * be transfered.<P> * From this method, the <code>DropTargetListener</code> * shall accept or reject the drop via the * acceptDrop(int dropAction) or rejectDrop() methods of the * <code>DropTargetDropEvent</code> parameter. * <P> * Subsequent to acceptDrop(), but not before, * <code>DropTargetDropEvent</code>'s getTransferable() * method may be invoked, and data transfer may be * performed via the returned <code>Transferable</code>'s * getTransferData() method. * <P> * At the completion of a drop, an implementation * of this method is required to signal the success/failure * of the drop by passing an appropriate * <code>boolean</code> to the <code>DropTargetDropEvent</code>'s * dropComplete(boolean success) method. * <P> * Note: The data transfer should be completed before the call to the * <code>DropTargetDropEvent</code>'s dropComplete(boolean success) method. * After that, a call to the getTransferData() method of the * <code>Transferable</code> returned by * <code>DropTargetDropEvent.getTransferable()</code> is guaranteed to * succeed only if the data transfer is local; that is, only if * <code>DropTargetDropEvent.isLocalTransfer()</code> returns * <code>true</code>. Otherwise, the behavior of the call is * implementation-dependent. * <P> * @param dtde the <code>DropTargetDropEvent</code> */ void drop(DropTargetDropEvent dtde); }