001/* DragSourceContext.java -- 002 Copyright (C) 2002 Free Software Foundation 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package java.awt.dnd; 040 041import java.awt.Component; 042import java.awt.Cursor; 043import java.awt.Image; 044import java.awt.Point; 045import java.awt.datatransfer.Transferable; 046import java.awt.dnd.peer.DragSourceContextPeer; 047import java.io.Serializable; 048import java.util.TooManyListenersException; 049 050/** 051 * @since 1.2 052 */ 053public class DragSourceContext 054 implements DragSourceListener, DragSourceMotionListener, Serializable 055{ 056 /** 057 * Compatible with JDK 1.2+ 058 */ 059 static final long serialVersionUID = -115407898692194719L; 060 061 protected static final int DEFAULT = 0; 062 protected static final int ENTER = 1; 063 protected static final int OVER = 2; 064 protected static final int CHANGED = 3; 065 066 private DragSourceContextPeer peer; 067 private Cursor cursor; 068 private Transferable transferable; 069 private DragGestureEvent trigger; 070 private DragSourceListener dragSourceListener; 071 private boolean useCustomCursor; 072 private int sourceActions; 073 private Image image; 074 private Point offset; 075 076 /** 077 * Initializes a drag source context. 078 * 079 * @exception IllegalArgumentException If Component or DragSource of trigger 080 * are null, the drag action for the trigger event is DnDConstants.ACTION_NONE 081 * or if the source actions for the DragGestureRecognizer associated with the 082 * trigger event are equal to DnDConstants.ACTION_NONE. 083 * @exception NullPointerException If peer, trans or trigger is null or if the 084 * image is not null but the offset is. 085 */ 086 public DragSourceContext (DragSourceContextPeer peer, 087 DragGestureEvent trigger, Cursor cursor, 088 Image image, Point offset, Transferable trans, 089 DragSourceListener dsl) 090 { 091 if (peer == null 092 || trigger == null || trans == null 093 || (image != null && offset == null)) 094 throw new NullPointerException (); 095 096 if (trigger.getComponent () == null 097 || trigger.getDragSource () == null 098 || trigger.getDragAction () == DnDConstants.ACTION_NONE 099 || trigger.getSourceAsDragGestureRecognizer () 100 .getSourceActions () == DnDConstants.ACTION_NONE) 101 throw new IllegalArgumentException (); 102 103 this.peer = peer; 104 this.trigger = trigger; 105 this.cursor = cursor; 106 this.image = image; 107 this.offset = offset; 108 this.transferable = trans; 109 this.dragSourceListener = dsl; 110 this.sourceActions = trigger.getSourceAsDragGestureRecognizer().getSourceActions(); 111 112 setCursor(cursor); 113 updateCurrentCursor(trigger.getDragAction(), sourceActions, DEFAULT); 114 } 115 116 /** 117 * Returns the DragSource object associated with the 118 * DragGestureEvent. 119 * 120 * @return the DragSource associated with the trigger. 121 */ 122 public DragSource getDragSource() 123 { 124 return trigger.getDragSource (); 125 } 126 127 /** 128 * Returns the component associated with this. 129 * 130 * @return the component associated with the trigger. 131 */ 132 public Component getComponent() 133 { 134 return trigger.getComponent (); 135 } 136 137 /** 138 * Gets the trigger associated with this. 139 * 140 * @return the trigger. 141 */ 142 public DragGestureEvent getTrigger() 143 { 144 return trigger; 145 } 146 147 /** 148 * Returns the source actions for the DragGestureRecognizer. 149 * 150 * @return the source actions for DragGestureRecognizer. 151 */ 152 public int getSourceActions() 153 { 154 if (sourceActions == 0) 155 sourceActions = trigger.getSourceAsDragGestureRecognizer().getSourceActions(); 156 return sourceActions; 157 } 158 159 /** 160 * Sets the cursor for this drag operation to the specified cursor. 161 * 162 * @param cursor c - the Cursor to use, or null to use the default drag 163 * cursor. 164 */ 165 public void setCursor(Cursor cursor) 166 { 167 if (cursor == null) 168 useCustomCursor = false; 169 else 170 useCustomCursor = true; 171 this.cursor = cursor; 172 peer.setCursor(cursor); 173 } 174 175 /** 176 * Returns the current cursor or null if the default 177 * drag cursor is used. 178 * 179 * @return the current cursor or null. 180 */ 181 public Cursor getCursor() 182 { 183 return cursor; 184 } 185 186 /** 187 * Adds a <code>DragSourceListener</code>. 188 * 189 * @exception TooManyListenersException If a <code>DragSourceListener</code> 190 * has already been added. 191 */ 192 public void addDragSourceListener (DragSourceListener dsl) 193 throws TooManyListenersException 194 { 195 if (dragSourceListener != null) 196 throw new TooManyListenersException (); 197 198 dragSourceListener = dsl; 199 } 200 201 public void removeDragSourceListener (DragSourceListener dsl) 202 { 203 if (dragSourceListener == dsl) 204 dragSourceListener = null; 205 } 206 207 /** 208 * This function tells the peer that the DataFlavors have been modified. 209 */ 210 public void transferablesFlavorsChanged() 211 { 212 peer.transferablesFlavorsChanged(); 213 } 214 215 /** 216 * Calls dragEnter on the listeners registered with this 217 * and with the DragSource. 218 * 219 * @param e - the DragSourceDragEvent 220 */ 221 public void dragEnter(DragSourceDragEvent e) 222 { 223 if (dragSourceListener != null) 224 dragSourceListener.dragEnter(e); 225 226 DragSource ds = getDragSource(); 227 DragSourceListener[] dsl = ds.getDragSourceListeners(); 228 for (int i = 0; i < dsl.length; i++) 229 dsl[i].dragEnter(e); 230 231 updateCurrentCursor(e.getDropAction(), e.getTargetActions(), ENTER); 232 } 233 234 /** 235 * Calls dragOver on the listeners registered with this 236 * and with the DragSource. 237 * 238 * @param e - the DragSourceDragEvent 239 */ 240 public void dragOver(DragSourceDragEvent e) 241 { 242 if (dragSourceListener != null) 243 dragSourceListener.dragOver(e); 244 245 DragSource ds = getDragSource(); 246 DragSourceListener[] dsl = ds.getDragSourceListeners(); 247 for (int i = 0; i < dsl.length; i++) 248 dsl[i].dragOver(e); 249 250 updateCurrentCursor(e.getDropAction(), e.getTargetActions(), OVER); 251 } 252 253 /** 254 * Calls dragExit on the listeners registered with this 255 * and with the DragSource. 256 * 257 * @param e - the DragSourceEvent 258 */ 259 public void dragExit(DragSourceEvent e) 260 { 261 if (dragSourceListener != null) 262 dragSourceListener.dragExit(e); 263 264 DragSource ds = getDragSource(); 265 DragSourceListener[] dsl = ds.getDragSourceListeners(); 266 for (int i = 0; i < dsl.length; i++) 267 dsl[i].dragExit(e); 268 269 updateCurrentCursor(DnDConstants.ACTION_NONE, DnDConstants.ACTION_NONE, 270 DEFAULT); 271 } 272 273 /** 274 * Calls dropActionChanged on the listeners registered with this 275 * and with the DragSource. 276 * 277 * @param e - the DragSourceDragEvent 278 */ 279 public void dropActionChanged(DragSourceDragEvent e) 280 { 281 if (dragSourceListener != null) 282 dragSourceListener.dropActionChanged(e); 283 284 DragSource ds = getDragSource(); 285 DragSourceListener[] dsl = ds.getDragSourceListeners(); 286 for (int i = 0; i < dsl.length; i++) 287 dsl[i].dropActionChanged(e); 288 289 updateCurrentCursor(e.getDropAction(), e.getTargetActions(), CHANGED); 290 } 291 292 /** 293 * Calls dragDropEnd on the listeners registered with this 294 * and with the DragSource. 295 * 296 * @param e - the DragSourceDropEvent 297 */ 298 public void dragDropEnd(DragSourceDropEvent e) 299 { 300 if (dragSourceListener != null) 301 dragSourceListener.dragDropEnd(e); 302 303 DragSource ds = getDragSource(); 304 DragSourceListener[] dsl = ds.getDragSourceListeners(); 305 for (int i = 0; i < dsl.length; i++) 306 dsl[i].dragDropEnd(e); 307 } 308 309 /** 310 * Calls dragMouseMoved on the listeners registered with the DragSource. 311 * 312 * @param e - the DragSourceDragEvent 313 */ 314 public void dragMouseMoved(DragSourceDragEvent e) 315 { 316 DragSource ds = getDragSource(); 317 DragSourceMotionListener[] dsml = ds.getDragSourceMotionListeners(); 318 for (int i = 0; i < dsml.length; i++) 319 dsml[i].dragMouseMoved(e); 320 } 321 322 /** 323 * Returns the Transferable set with this object. 324 * 325 * @return the transferable. 326 */ 327 public Transferable getTransferable() 328 { 329 return transferable; 330 } 331 332 /** 333 * This function sets the drag cursor for the specified operation, actions and 334 * status if the default drag cursor is active. Otherwise, the cursor is not 335 * updated in any way. 336 * 337 * @param dropOp - the current operation. 338 * @param targetAct - the supported actions. 339 * @param status - the status of the cursor (constant). 340 */ 341 protected void updateCurrentCursor(int dropOp, int targetAct, int status) 342 { 343 if (! useCustomCursor) 344 { 345 Cursor newCursor = null; 346 switch (status) 347 { 348 default: 349 targetAct = DnDConstants.ACTION_NONE; 350 case ENTER: 351 case CHANGED: 352 case OVER: 353 int action = dropOp & targetAct; 354 if (action == DnDConstants.ACTION_NONE) 355 { 356 if ((dropOp & DnDConstants.ACTION_LINK) != 0) 357 newCursor = DragSource.DefaultLinkNoDrop; 358 else if ((dropOp & DnDConstants.ACTION_MOVE) != 0) 359 newCursor = DragSource.DefaultMoveNoDrop; 360 else 361 newCursor = DragSource.DefaultCopyNoDrop; 362 } 363 else 364 { 365 if ((dropOp & DnDConstants.ACTION_LINK) != 0) 366 newCursor = DragSource.DefaultLinkDrop; 367 else if ((dropOp & DnDConstants.ACTION_MOVE) != 0) 368 newCursor = DragSource.DefaultMoveDrop; 369 else 370 newCursor = DragSource.DefaultCopyDrop; 371 } 372 } 373 374 if (cursor == null || ! cursor.equals(newCursor)) 375 { 376 cursor = newCursor; 377 DragSourceContextPeer p = peer; 378 if (p != null) 379 p.setCursor(cursor); 380 } 381 } 382 } 383} // class DragSourceContext