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| 1 | +/* | |
| 2 | + * Copyright (c) 2001, 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 | +package java.awt.dnd; | |
| 26 | + | |
| 27 | +import java.awt.AWTEventMulticaster; | |
| 28 | +import java.io.ObjectOutputStream; | |
| 29 | +import java.io.IOException; | |
| 30 | +import java.util.EventListener; | |
| 31 | + | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * A class extends <code>AWTEventMulticaster</code> to implement efficient and | |
| 35 | + * thread-safe multi-cast event dispatching for the drag-and-drop events defined | |
| 36 | + * in the java.awt.dnd package. | |
| 37 | + * | |
| 38 | + * @since 1.4 | |
| 39 | + * @see AWTEventMulticaster | |
| 40 | + */ | |
| 41 | + | |
| 42 | +class DnDEventMulticaster extends AWTEventMulticaster | |
| 43 | + implements DragSourceListener, DragSourceMotionListener { | |
| 44 | + | |
| 45 | + /** | |
| 46 | + * Creates an event multicaster instance which chains listener-a | |
| 47 | + * with listener-b. Input parameters <code>a</code> and <code>b</code> | |
| 48 | + * should not be <code>null</code>, though implementations may vary in | |
| 49 | + * choosing whether or not to throw <code>NullPointerException</code> | |
| 50 | + * in that case. | |
| 51 | + * | |
| 52 | + * @param a listener-a | |
| 53 | + * @param b listener-b | |
| 54 | + */ | |
| 55 | + protected DnDEventMulticaster(EventListener a, EventListener b) { | |
| 56 | + super(a,b); | |
| 57 | + } | |
| 58 | + | |
| 59 | + /** | |
| 60 | + * Handles the <code>DragSourceDragEvent</code> by invoking | |
| 61 | + * <code>dragEnter</code> on listener-a and listener-b. | |
| 62 | + * | |
| 63 | + * @param dsde the <code>DragSourceDragEvent</code> | |
| 64 | + */ | |
| 65 | + public void dragEnter(DragSourceDragEvent dsde) { | |
| 66 | + ((DragSourceListener)a).dragEnter(dsde); | |
| 67 | + ((DragSourceListener)b).dragEnter(dsde); | |
| 68 | + } | |
| 69 | + | |
| 70 | + /** | |
| 71 | + * Handles the <code>DragSourceDragEvent</code> by invoking | |
| 72 | + * <code>dragOver</code> on listener-a and listener-b. | |
| 73 | + * | |
| 74 | + * @param e the <code>DragSourceDragEvent</code> | |
| 75 | + */ | |
| 76 | + public void dragOver(DragSourceDragEvent dsde) { | |
| 77 | + ((DragSourceListener)a).dragOver(dsde); | |
| 78 | + ((DragSourceListener)b).dragOver(dsde); | |
| 79 | + } | |
| 80 | + | |
| 81 | + /** | |
| 82 | + * Handles the <code>DragSourceDragEvent</code> by invoking | |
| 83 | + * <code>dropActionChanged</code> on listener-a and listener-b. | |
| 84 | + * | |
| 85 | + * @param dsde the <code>DragSourceDragEvent</code> | |
| 86 | + */ | |
| 87 | + public void dropActionChanged(DragSourceDragEvent dsde) { | |
| 88 | + ((DragSourceListener)a).dropActionChanged(dsde); | |
| 89 | + ((DragSourceListener)b).dropActionChanged(dsde); | |
| 90 | + } | |
| 91 | + | |
| 92 | + /** | |
| 93 | + * Handles the <code>DragSourceEvent</code> by invoking | |
| 94 | + * <code>dragExit</code> on listener-a and listener-b. | |
| 95 | + * | |
| 96 | + * @param dse the <code>DragSourceEvent</code> | |
| 97 | + */ | |
| 98 | + public void dragExit(DragSourceEvent dse) { | |
| 99 | + ((DragSourceListener)a).dragExit(dse); | |
| 100 | + ((DragSourceListener)b).dragExit(dse); | |
| 101 | + } | |
| 102 | + | |
| 103 | + /** | |
| 104 | + * Handles the <code>DragSourceDropEvent</code> by invoking | |
| 105 | + * <code>dragDropEnd</code> on listener-a and listener-b. | |
| 106 | + * | |
| 107 | + * @param dsde the <code>DragSourceDropEvent</code> | |
| 108 | + */ | |
| 109 | + public void dragDropEnd(DragSourceDropEvent dsde) { | |
| 110 | + ((DragSourceListener)a).dragDropEnd(dsde); | |
| 111 | + ((DragSourceListener)b).dragDropEnd(dsde); | |
| 112 | + } | |
| 113 | + | |
| 114 | + /** | |
| 115 | + * Handles the <code>DragSourceDragEvent</code> by invoking | |
| 116 | + * <code>dragMouseMoved</code> on listener-a and listener-b. | |
| 117 | + * | |
| 118 | + * @param dsde the <code>DragSourceDragEvent</code> | |
| 119 | + */ | |
| 120 | + public void dragMouseMoved(DragSourceDragEvent dsde) { | |
| 121 | + ((DragSourceMotionListener)a).dragMouseMoved(dsde); | |
| 122 | + ((DragSourceMotionListener)b).dragMouseMoved(dsde); | |
| 123 | + } | |
| 124 | + | |
| 125 | + /** | |
| 126 | + * Adds drag-source-listener-a with drag-source-listener-b and | |
| 127 | + * returns the resulting multicast listener. | |
| 128 | + * | |
| 129 | + * @param a drag-source-listener-a | |
| 130 | + * @param b drag-source-listener-b | |
| 131 | + */ | |
| 132 | + public static DragSourceListener add(DragSourceListener a, | |
| 133 | + DragSourceListener b) { | |
| 134 | + return (DragSourceListener)addInternal(a, b); | |
| 135 | + } | |
| 136 | + | |
| 137 | + /** | |
| 138 | + * Adds drag-source-motion-listener-a with drag-source-motion-listener-b and | |
| 139 | + * returns the resulting multicast listener. | |
| 140 | + * | |
| 141 | + * @param a drag-source-motion-listener-a | |
| 142 | + * @param b drag-source-motion-listener-b | |
| 143 | + */ | |
| 144 | + public static DragSourceMotionListener add(DragSourceMotionListener a, | |
| 145 | + DragSourceMotionListener b) { | |
| 146 | + return (DragSourceMotionListener)addInternal(a, b); | |
| 147 | + } | |
| 148 | + | |
| 149 | + /** | |
| 150 | + * Removes the old drag-source-listener from drag-source-listener-l | |
| 151 | + * and returns the resulting multicast listener. | |
| 152 | + * | |
| 153 | + * @param l drag-source-listener-l | |
| 154 | + * @param oldl the drag-source-listener being removed | |
| 155 | + */ | |
| 156 | + public static DragSourceListener remove(DragSourceListener l, | |
| 157 | + DragSourceListener oldl) { | |
| 158 | + return (DragSourceListener)removeInternal(l, oldl); | |
| 159 | + } | |
| 160 | + | |
| 161 | + /** | |
| 162 | + * Removes the old drag-source-motion-listener from | |
| 163 | + * drag-source-motion-listener-l and returns the resulting multicast | |
| 164 | + * listener. | |
| 165 | + * | |
| 166 | + * @param l drag-source-motion-listener-l | |
| 167 | + * @param ol the drag-source-motion-listener being removed | |
| 168 | + */ | |
| 169 | + public static DragSourceMotionListener remove(DragSourceMotionListener l, | |
| 170 | + DragSourceMotionListener ol) { | |
| 171 | + return (DragSourceMotionListener)removeInternal(l, ol); | |
| 172 | + } | |
| 173 | + | |
| 174 | + /** | |
| 175 | + * Returns the resulting multicast listener from adding listener-a | |
| 176 | + * and listener-b together. | |
| 177 | + * If listener-a is null, it returns listener-b; | |
| 178 | + * If listener-b is null, it returns listener-a | |
| 179 | + * If neither are null, then it creates and returns | |
| 180 | + * a new AWTEventMulticaster instance which chains a with b. | |
| 181 | + * @param a event listener-a | |
| 182 | + * @param b event listener-b | |
| 183 | + */ | |
| 184 | + protected static EventListener addInternal(EventListener a, EventListener b) { | |
| 185 | + if (a == null) return b; | |
| 186 | + if (b == null) return a; | |
| 187 | + return new DnDEventMulticaster(a, b); | |
| 188 | + } | |
| 189 | + | |
| 190 | + /** | |
| 191 | + * Removes a listener from this multicaster and returns the | |
| 192 | + * resulting multicast listener. | |
| 193 | + * @param oldl the listener to be removed | |
| 194 | + */ | |
| 195 | + protected EventListener remove(EventListener oldl) { | |
| 196 | + if (oldl == a) return b; | |
| 197 | + if (oldl == b) return a; | |
| 198 | + EventListener a2 = removeInternal(a, oldl); | |
| 199 | + EventListener b2 = removeInternal(b, oldl); | |
| 200 | + if (a2 == a && b2 == b) { | |
| 201 | + return this; // it's not here | |
| 202 | + } | |
| 203 | + return addInternal(a2, b2); | |
| 204 | + } | |
| 205 | + | |
| 206 | + /** | |
| 207 | + * Returns the resulting multicast listener after removing the | |
| 208 | + * old listener from listener-l. | |
| 209 | + * If listener-l equals the old listener OR listener-l is null, | |
| 210 | + * returns null. | |
| 211 | + * Else if listener-l is an instance of AWTEventMulticaster, | |
| 212 | + * then it removes the old listener from it. | |
| 213 | + * Else, returns listener l. | |
| 214 | + * @param l the listener being removed from | |
| 215 | + * @param oldl the listener being removed | |
| 216 | + */ | |
| 217 | + protected static EventListener removeInternal(EventListener l, EventListener oldl) { | |
| 218 | + if (l == oldl || l == null) { | |
| 219 | + return null; | |
| 220 | + } else if (l instanceof DnDEventMulticaster) { | |
| 221 | + return ((DnDEventMulticaster)l).remove(oldl); | |
| 222 | + } else { | |
| 223 | + return l; // it's not here | |
| 224 | + } | |
| 225 | + } | |
| 226 | + | |
| 227 | + protected static void save(ObjectOutputStream s, String k, EventListener l) | |
| 228 | + throws IOException { | |
| 229 | + AWTEventMulticaster.save(s, k, l); | |
| 230 | + } | |
| 231 | +} | |