1/* 2 * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26package java.awt.dnd; 27 28import java.util.EventListener; 29 30import java.awt.dnd.DropTargetDragEvent; 31import java.awt.dnd.DropTargetDropEvent; 32 33/** 34 * The {@code DropTargetListener} interface 35 * is the callback interface used by the 36 * {@code DropTarget} class to provide 37 * notification of DnD operations that involve 38 * the subject {@code DropTarget}. Methods of 39 * this interface may be implemented to provide 40 * "drag under" visual feedback to the user throughout 41 * the Drag and Drop operation. 42 * <p> 43 * Create a listener object by implementing the interface and then register it 44 * with a {@code DropTarget}. When the drag enters, moves over, or exits 45 * the operable part of the drop site for that {@code DropTarget}, when 46 * the drop action changes, and when the drop occurs, the relevant method in 47 * the listener object is invoked, and the {@code DropTargetEvent} is 48 * passed to it. 49 * <p> 50 * The operable part of the drop site for the {@code DropTarget} is 51 * the part of the associated {@code Component}'s geometry that is not 52 * obscured by an overlapping top-level window or by another 53 * {@code Component} higher in the Z-order that has an associated active 54 * {@code DropTarget}. 55 * <p> 56 * During the drag, the data associated with the current drag operation can be 57 * retrieved by calling {@code getTransferable()} on 58 * {@code DropTargetDragEvent} instances passed to the listener's 59 * methods. 60 * <p> 61 * Note that {@code getTransferable()} on the 62 * {@code DropTargetDragEvent} instance should only be called within the 63 * respective listener's method and all the necessary data should be retrieved 64 * from the returned {@code Transferable} before that method returns. 65 * 66 * @since 1.2 67 */ 68 69public interface DropTargetListener extends EventListener { 70 71 /** 72 * Called while a drag operation is ongoing, when the mouse pointer enters 73 * the operable part of the drop site for the {@code DropTarget} 74 * registered with this listener. 75 * 76 * @param dtde the {@code DropTargetDragEvent} 77 */ 78 79 void dragEnter(DropTargetDragEvent dtde); 80 81 /** 82 * Called when a drag operation is ongoing, while the mouse pointer is still 83 * over the operable part of the drop site for the {@code DropTarget} 84 * registered with this listener. 85 * 86 * @param dtde the {@code DropTargetDragEvent} 87 */ 88 89 void dragOver(DropTargetDragEvent dtde); 90 91 /** 92 * Called if the user has modified 93 * the current drop gesture. 94 * 95 * @param dtde the {@code DropTargetDragEvent} 96 */ 97 98 void dropActionChanged(DropTargetDragEvent dtde); 99 100 /** 101 * Called while a drag operation is ongoing, when the mouse pointer has 102 * exited the operable part of the drop site for the 103 * {@code DropTarget} registered with this listener. 104 * 105 * @param dte the {@code DropTargetEvent} 106 */ 107 108 void dragExit(DropTargetEvent dte); 109 110 /** 111 * Called when the drag operation has terminated with a drop on 112 * the operable part of the drop site for the {@code DropTarget} 113 * registered with this listener. 114 * <p> 115 * This method is responsible for undertaking 116 * the transfer of the data associated with the 117 * gesture. The {@code DropTargetDropEvent} 118 * provides a means to obtain a {@code Transferable} 119 * object that represents the data object(s) to 120 * be transferred.<P> 121 * From this method, the {@code DropTargetListener} 122 * shall accept or reject the drop via the 123 * acceptDrop(int dropAction) or rejectDrop() methods of the 124 * {@code DropTargetDropEvent} parameter. 125 * <P> 126 * Subsequent to acceptDrop(), but not before, 127 * {@code DropTargetDropEvent}'s getTransferable() 128 * method may be invoked, and data transfer may be 129 * performed via the returned {@code Transferable}'s 130 * getTransferData() method. 131 * <P> 132 * At the completion of a drop, an implementation 133 * of this method is required to signal the success/failure 134 * of the drop by passing an appropriate 135 * {@code boolean} to the {@code DropTargetDropEvent}'s 136 * dropComplete(boolean success) method. 137 * <P> 138 * Note: The data transfer should be completed before the call to the 139 * {@code DropTargetDropEvent}'s dropComplete(boolean success) method. 140 * After that, a call to the getTransferData() method of the 141 * {@code Transferable} returned by 142 * {@code DropTargetDropEvent.getTransferable()} is guaranteed to 143 * succeed only if the data transfer is local; that is, only if 144 * {@code DropTargetDropEvent.isLocalTransfer()} returns 145 * {@code true}. Otherwise, the behavior of the call is 146 * implementation-dependent. 147 * 148 * @param dtde the {@code DropTargetDropEvent} 149 */ 150 151 void drop(DropTargetDropEvent dtde); 152} 153