J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2005 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any 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 ((DragRecognitionSupport)getDragRecognitionSupport()). |
| 77 | mousePressedImpl(me); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * If a dnd recognition has been going on, return the MouseEvent |
| 82 | * that started the recognition. Otherwise, return null. |
| 83 | */ |
| 84 | public static MouseEvent mouseReleased(MouseEvent me) { |
| 85 | return ((DragRecognitionSupport)getDragRecognitionSupport()). |
| 86 | mouseReleasedImpl(me); |
| 87 | } |
| 88 | |
| 89 | /** |
| 90 | * Returns whether or not a drag gesture recognition is ongoing. |
| 91 | */ |
| 92 | public static boolean mouseDragged(MouseEvent me, BeforeDrag bd) { |
| 93 | return ((DragRecognitionSupport)getDragRecognitionSupport()). |
| 94 | mouseDraggedImpl(me, bd); |
| 95 | } |
| 96 | |
| 97 | private void clearState() { |
| 98 | dndArmedEvent = null; |
| 99 | component = null; |
| 100 | } |
| 101 | |
| 102 | private int mapDragOperationFromModifiers(MouseEvent me, |
| 103 | TransferHandler th) { |
| 104 | |
| 105 | if (th == null || !SwingUtilities.isLeftMouseButton(me)) { |
| 106 | return TransferHandler.NONE; |
| 107 | } |
| 108 | |
| 109 | return SunDragSourceContextPeer. |
| 110 | convertModifiersToDropAction(me.getModifiersEx(), |
| 111 | th.getSourceActions(component)); |
| 112 | } |
| 113 | |
| 114 | /** |
| 115 | * Returns whether or not the event is potentially part of a drag sequence. |
| 116 | */ |
| 117 | private boolean mousePressedImpl(MouseEvent me) { |
| 118 | component = (JComponent)me.getSource(); |
| 119 | |
| 120 | if (mapDragOperationFromModifiers(me, component.getTransferHandler()) |
| 121 | != TransferHandler.NONE) { |
| 122 | |
| 123 | motionThreshold = DragSource.getDragThreshold(); |
| 124 | dndArmedEvent = me; |
| 125 | return true; |
| 126 | } |
| 127 | |
| 128 | clearState(); |
| 129 | return false; |
| 130 | } |
| 131 | |
| 132 | /** |
| 133 | * If a dnd recognition has been going on, return the MouseEvent |
| 134 | * that started the recognition. Otherwise, return null. |
| 135 | */ |
| 136 | private MouseEvent mouseReleasedImpl(MouseEvent me) { |
| 137 | /* no recognition has been going on */ |
| 138 | if (dndArmedEvent == null) { |
| 139 | return null; |
| 140 | } |
| 141 | |
| 142 | MouseEvent retEvent = null; |
| 143 | |
| 144 | if (me.getSource() == component) { |
| 145 | retEvent = dndArmedEvent; |
| 146 | } // else component has changed unexpectedly, so return null |
| 147 | |
| 148 | clearState(); |
| 149 | return retEvent; |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * Returns whether or not a drag gesture recognition is ongoing. |
| 154 | */ |
| 155 | private boolean mouseDraggedImpl(MouseEvent me, BeforeDrag bd) { |
| 156 | /* no recognition is in progress */ |
| 157 | if (dndArmedEvent == null) { |
| 158 | return false; |
| 159 | } |
| 160 | |
| 161 | /* component has changed unexpectedly, so bail */ |
| 162 | if (me.getSource() != component) { |
| 163 | clearState(); |
| 164 | return false; |
| 165 | } |
| 166 | |
| 167 | int dx = Math.abs(me.getX() - dndArmedEvent.getX()); |
| 168 | int dy = Math.abs(me.getY() - dndArmedEvent.getY()); |
| 169 | if ((dx > motionThreshold) || (dy > motionThreshold)) { |
| 170 | TransferHandler th = component.getTransferHandler(); |
| 171 | int action = mapDragOperationFromModifiers(me, th); |
| 172 | if (action != TransferHandler.NONE) { |
| 173 | /* notify the BeforeDrag instance */ |
| 174 | if (bd != null) { |
| 175 | bd.dragStarting(dndArmedEvent); |
| 176 | } |
| 177 | th.exportAsDrag(component, dndArmedEvent, action); |
| 178 | clearState(); |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | return true; |
| 183 | } |
| 184 | } |