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    1   /*
    2    * Copyright (c) 2005, 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 sun.awt;
   26   
   27   import java.awt.Component;
   28   import java.awt.Rectangle;
   29   import java.awt.event.PaintEvent;
   30   
   31   /**
   32    * PaintEventDispatcher is responsible for dispatching PaintEvents.  There
   33    * can be only one PaintEventDispatcher active at a particular time.
   34    *
   35    */
   36   public class PaintEventDispatcher {
   37       /**
   38        * Singleton dispatcher.
   39        */
   40       private static PaintEventDispatcher dispatcher;
   41   
   42       /**
   43        * Sets the current <code>PaintEventDispatcher</code>.
   44        *
   45        * @param dispatcher PaintEventDispatcher
   46        */
   47       public static void setPaintEventDispatcher(
   48                             PaintEventDispatcher dispatcher) {
   49           synchronized(PaintEventDispatcher.class) {
   50               PaintEventDispatcher.dispatcher = dispatcher;
   51           }
   52       }
   53   
   54       /**
   55        * Returns the currently active <code>PaintEventDispatcher</code>.  This
   56        * will never return null.
   57        *
   58        * @return PaintEventDispatcher
   59        */
   60       public static PaintEventDispatcher getPaintEventDispatcher() {
   61           synchronized(PaintEventDispatcher.class) {
   62               if (dispatcher == null) {
   63                   dispatcher = new PaintEventDispatcher();
   64               }
   65               return dispatcher;
   66           }
   67       }
   68   
   69       /**
   70        * Creates and returns the <code>PaintEvent</code> that should be
   71        * dispatched for the specified component.  If this returns null
   72        * no <code>PaintEvent</code> is dispatched.
   73        * <p>
   74        * <b>WARNING:</b> This is invoked from the native thread, be careful
   75        * what methods you end up invoking here.
   76        */
   77       public PaintEvent createPaintEvent(Component target, int x, int y, int w,
   78                                          int h) {
   79   
   80           return new PaintEvent((Component)target, PaintEvent.PAINT,
   81                                 new Rectangle(x, y, w, h));
   82       }
   83   
   84       /**
   85        * Returns true if a native background erase should be done for
   86        * the specified Component.
   87        */
   88       public boolean shouldDoNativeBackgroundErase(Component c) {
   89           return true;
   90       }
   91   
   92       /**
   93        * This method is invoked from the toolkit thread when the surface
   94        * data of the component needs to be replaced. The method run() of
   95        * the Runnable argument performs surface data replacing, run()
   96        * should be invoked on the EDT of this component's AppContext.
   97        * Returns true if the Runnable has been enqueued to be invoked
   98        * on the EDT.
   99        * (Fix 6255371.)
  100        */
  101       public boolean queueSurfaceDataReplacing(Component c, Runnable r) {
  102           return false;
  103       }
  104   }

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