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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 | } | ||