libjava/classpath/java/awt/LightweightDispatcher.java

   1 /* LightweightDispatcher.java -- Dispatches mouse events to lightweights
   2    Copyright (C) 2006 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.awt;
  40
  41 import gnu.java.awt.AWTUtilities;
  42
  43 import java.awt.event.MouseEvent;
  44 import java.util.WeakHashMap;
  45
  46 /**
  47  * Redispatches mouse events to lightweight components. The native peers know
  48  * nothing about the lightweight components and thus mouse events are always
  49  * targetted at Windows or heavyweight components. This class listenes directly
  50  * on the eventqueue and dispatches mouse events to lightweight components.
  51  *
  52  * @author Roman Kennke (kennke@aicas.com)
  53  */
  54 class LightweightDispatcher
  55 {
  56
  57   /**
  58    * Maps thread groups to lightweight dispatcher instances. We need to
  59    * have one instance per thread group so that 2 or more applets or otherwise
  60    * separated applications (like in OSGI) do not interfer with each other.
  61    */
  62   private static WeakHashMap instances = new WeakHashMap();
  63
  64   /**
  65    * The component that is the start of a mouse dragging. All MOUSE_DRAGGED
  66    * events that follow the initial press must have the source set to this,
  67    * as well as the MOUSE_RELEASED event following the dragging.
  68    */
  69   private Component dragTarget;
  70
  71   /**
  72    * The last mouse event target. If the target changes, additional
  73    * MOUSE_ENTERED and MOUSE_EXITED events must be dispatched.
  74    */
  75   private Component lastTarget;
  76
  77   /**
  78    * Returns an instance of LightweightDispatcher for the current thread's
  79    * thread group.
  80    *
  81    * @return an instance of LightweightDispatcher for the current thread's
  82    *         thread group
  83    */
  84   static LightweightDispatcher getInstance()
  85   {
  86     Thread t = Thread.currentThread();
  87     ThreadGroup tg = t.getThreadGroup();
  88     LightweightDispatcher instance = (LightweightDispatcher) instances.get(tg);
  89     if (instance == null)
  90       {
  91         instance = new LightweightDispatcher();
  92         instances.put(tg, instance);
  93       }
  94     return instance;
  95   }
  96
  97   /**
  98    * Creates a new LightweightDispatcher. This is private to prevent access
  99    * from outside. Use {@link #getInstance()} instead.
 100    */
 101   private LightweightDispatcher()
 102   {
 103     // Nothing to do here.
 104   }
 105
 106   /**
 107    * Receives notification if a mouse event passes along the eventqueue.
 108    *
 109    * @param event the event
 110    */
 111   public boolean dispatchEvent(AWTEvent event)
 112   {
 113     boolean dispatched = false;
 114     if (event instanceof MouseEvent && event.getSource() instanceof Window)
 115       {
 116         MouseEvent mouseEvent = (MouseEvent) event;
 117         handleMouseEvent(mouseEvent);
 118         dispatched = true;
 119       }
 120     return dispatched;
 121   }
 122
 123   /**
 124    * Handles all mouse events that are targetted at toplevel containers
 125    * (Window instances) and dispatches them to the correct lightweight child.
 126    *
 127    * @param ev the mouse event
 128    */
 129   private void handleMouseEvent(MouseEvent ev)
 130   {
 131     Window window = (Window) ev.getSource();
 132     Component target = window.findComponentAt(ev.getX(), ev.getY());
 133     if (target != null && target.isLightweight())
 134       {
 135         // Dispatch additional MOUSE_EXITED and MOUSE_ENTERED if event target
 136         // is different from the last event target.
 137         if (target != lastTarget)
 138           {
 139             if (lastTarget != null)
 140               {
 141                 Point p1 = AWTUtilities.convertPoint(window, ev.getX(),
 142                                                      ev.getY(), lastTarget);
 143                 MouseEvent mouseExited =
 144                   new MouseEvent(lastTarget, MouseEvent.MOUSE_EXITED,
 145                                  ev.getWhen(), ev.getModifiers(), p1.x, p1.y,
 146                                  ev.getClickCount(), ev.isPopupTrigger());
 147                 lastTarget.dispatchEvent(mouseExited);
 148               }
 149             Point p = AWTUtilities.convertPoint(window, ev.getX(), ev.getY(),
 150                                                 target);
 151             MouseEvent mouseEntered =
 152               new MouseEvent(target, MouseEvent.MOUSE_ENTERED, ev.getWhen(),
 153                              ev.getModifiers(), p.x, p.y, ev.getClickCount(),
 154                              ev.isPopupTrigger());
 155             target.dispatchEvent(mouseEntered);
 156           }
 157
 158         switch (ev.getID())
 159         {
 160           case MouseEvent.MOUSE_PRESSED:
 161             dragTarget = target;
 162             break;
 163           case MouseEvent.MOUSE_RELEASED:
 164             if (dragTarget != null)
 165               target = dragTarget;
 166             dragTarget = null;
 167             break;
 168           case MouseEvent.MOUSE_CLICKED:
 169             // When we receive a MOUSE_CLICKED, we set the target to the
 170             // previous target, which must have been a MOUSE_RELEASED event.
 171             // This is necessary for the case when the MOUSE_RELEASED has
 172             // caused the original target (like an internal component) go
 173             // away.
 174             target = lastTarget;
 175             break;
 176           case MouseEvent.MOUSE_DRAGGED:
 177             target = dragTarget;
 178             break;
 179           default:
 180             // Do nothing in other cases.
 181             break;
 182         }
 183
 184         lastTarget = target;
 185
 186         Point targetCoordinates =
 187           AWTUtilities.convertPoint(window, ev.getX(), ev.getY(), target);
 188         int dx = targetCoordinates.x - ev.getX();
 189         int dy = targetCoordinates.y - ev.getY();
 190         ev.translatePoint(dx, dy);
 191         ev.setSource(target);
 192         target.dispatchEvent(ev);
 193
 194         // We reset the event, so that the normal event dispatching is not
 195         // influenced by this modified event.
 196         ev.setSource(window);
 197         ev.translatePoint(-dx, -dy);
 198       }
 199   }
 200 }