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| 1 | +/* | |
| 2 | + * Copyright (c) 2005, 2008, 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 javax.swing.plaf.basic; | |
| 26 | + | |
| 27 | +import java.awt.Toolkit; | |
| 28 | +import java.awt.event.*; | |
| 29 | +import java.awt.dnd.DragSource; | |
| 30 | +import javax.swing.*; | |
| 31 | +import sun.awt.dnd.SunDragSourceContextPeer; | |
| 32 | +import sun.awt.AppContext; | |
| 33 | + | |
| 34 | +/** | |
| 35 | + * Drag gesture recognition support for classes that have a | |
| 36 | + * <code>TransferHandler</code>. The gesture for a drag in this class is a mouse | |
| 37 | + * press followed by movement by <code>DragSource.getDragThreshold()</code> | |
| 38 | + * pixels. An instance of this class is maintained per AppContext, and the | |
| 39 | + * public static methods call into the appropriate instance. | |
| 40 | + * | |
| 41 | + * @author Shannon Hickey | |
| 42 | + */ | |
| 43 | +class DragRecognitionSupport { | |
| 44 | + private int motionThreshold; | |
| 45 | + private MouseEvent dndArmedEvent; | |
| 46 | + private JComponent component; | |
| 47 | + | |
| 48 | + /** | |
| 49 | + * This interface allows us to pass in a handler to mouseDragged, | |
| 50 | + * so that we can be notified immediately before a drag begins. | |
| 51 | + */ | |
| 52 | + public static interface BeforeDrag { | |
| 53 | + public void dragStarting(MouseEvent me); | |
| 54 | + } | |
| 55 | + | |
| 56 | + /** | |
| 57 | + * Returns the DragRecognitionSupport for the caller's AppContext. | |
| 58 | + */ | |
| 59 | + private static DragRecognitionSupport getDragRecognitionSupport() { | |
| 60 | + DragRecognitionSupport support = | |
| 61 | + (DragRecognitionSupport)AppContext.getAppContext(). | |
| 62 | + get(DragRecognitionSupport.class); | |
| 63 | + | |
| 64 | + if (support == null) { | |
| 65 | + support = new DragRecognitionSupport(); | |
| 66 | + AppContext.getAppContext().put(DragRecognitionSupport.class, support); | |
| 67 | + } | |
| 68 | + | |
| 69 | + return support; | |
| 70 | + } | |
| 71 | + | |
| 72 | + /** | |
| 73 | + * Returns whether or not the event is potentially part of a drag sequence. | |
| 74 | + */ | |
| 75 | + public static boolean mousePressed(MouseEvent me) { | |
| 76 | + return getDragRecognitionSupport().mousePressedImpl(me); | |
| 77 | + } | |
| 78 | + | |
| 79 | + /** | |
| 80 | + * If a dnd recognition has been going on, return the MouseEvent | |
| 81 | + * that started the recognition. Otherwise, return null. | |
| 82 | + */ | |
| 83 | + public static MouseEvent mouseReleased(MouseEvent me) { | |
| 84 | + return getDragRecognitionSupport().mouseReleasedImpl(me); | |
| 85 | + } | |
| 86 | + | |
| 87 | + /** | |
| 88 | + * Returns whether or not a drag gesture recognition is ongoing. | |
| 89 | + */ | |
| 90 | + public static boolean mouseDragged(MouseEvent me, BeforeDrag bd) { | |
| 91 | + return getDragRecognitionSupport().mouseDraggedImpl(me, bd); | |
| 92 | + } | |
| 93 | + | |
| 94 | + private void clearState() { | |
| 95 | + dndArmedEvent = null; | |
| 96 | + component = null; | |
| 97 | + } | |
| 98 | + | |
| 99 | + private int mapDragOperationFromModifiers(MouseEvent me, | |
| 100 | + TransferHandler th) { | |
| 101 | + | |
| 102 | + if (th == null || !SwingUtilities.isLeftMouseButton(me)) { | |
| 103 | + return TransferHandler.NONE; | |
| 104 | + } | |
| 105 | + | |
| 106 | + return SunDragSourceContextPeer. | |
| 107 | + convertModifiersToDropAction(me.getModifiersEx(), | |
| 108 | + th.getSourceActions(component)); | |
| 109 | + } | |
| 110 | + | |
| 111 | + /** | |
| 112 | + * Returns whether or not the event is potentially part of a drag sequence. | |
| 113 | + */ | |
| 114 | + private boolean mousePressedImpl(MouseEvent me) { | |
| 115 | + component = (JComponent)me.getSource(); | |
| 116 | + | |
| 117 | + if (mapDragOperationFromModifiers(me, component.getTransferHandler()) | |
| 118 | + != TransferHandler.NONE) { | |
| 119 | + | |
| 120 | + motionThreshold = DragSource.getDragThreshold(); | |
| 121 | + dndArmedEvent = me; | |
| 122 | + return true; | |
| 123 | + } | |
| 124 | + | |
| 125 | + clearState(); | |
| 126 | + return false; | |
| 127 | + } | |
| 128 | + | |
| 129 | + /** | |
| 130 | + * If a dnd recognition has been going on, return the MouseEvent | |
| 131 | + * that started the recognition. Otherwise, return null. | |
| 132 | + */ | |
| 133 | + private MouseEvent mouseReleasedImpl(MouseEvent me) { | |
| 134 | + /* no recognition has been going on */ | |
| 135 | + if (dndArmedEvent == null) { | |
| 136 | + return null; | |
| 137 | + } | |
| 138 | + | |
| 139 | + MouseEvent retEvent = null; | |
| 140 | + | |
| 141 | + if (me.getSource() == component) { | |
| 142 | + retEvent = dndArmedEvent; | |
| 143 | + } // else component has changed unexpectedly, so return null | |
| 144 | + | |
| 145 | + clearState(); | |
| 146 | + return retEvent; | |
| 147 | + } | |
| 148 | + | |
| 149 | + /** | |
| 150 | + * Returns whether or not a drag gesture recognition is ongoing. | |
| 151 | + */ | |
| 152 | + private boolean mouseDraggedImpl(MouseEvent me, BeforeDrag bd) { | |
| 153 | + /* no recognition is in progress */ | |
| 154 | + if (dndArmedEvent == null) { | |
| 155 | + return false; | |
| 156 | + } | |
| 157 | + | |
| 158 | + /* component has changed unexpectedly, so bail */ | |
| 159 | + if (me.getSource() != component) { | |
| 160 | + clearState(); | |
| 161 | + return false; | |
| 162 | + } | |
| 163 | + | |
| 164 | + int dx = Math.abs(me.getX() - dndArmedEvent.getX()); | |
| 165 | + int dy = Math.abs(me.getY() - dndArmedEvent.getY()); | |
| 166 | + if ((dx > motionThreshold) || (dy > motionThreshold)) { | |
| 167 | + TransferHandler th = component.getTransferHandler(); | |
| 168 | + int action = mapDragOperationFromModifiers(me, th); | |
| 169 | + if (action != TransferHandler.NONE) { | |
| 170 | + /* notify the BeforeDrag instance */ | |
| 171 | + if (bd != null) { | |
| 172 | + bd.dragStarting(dndArmedEvent); | |
| 173 | + } | |
| 174 | + th.exportAsDrag(component, dndArmedEvent, action); | |
| 175 | + clearState(); | |
| 176 | + } | |
| 177 | + } | |
| 178 | + | |
| 179 | + return true; | |
| 180 | + } | |
| 181 | +} | |