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    1   /*
    2    * Copyright (c) 2005, 2011, 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.swing;
   26   
   27   import java.util;
   28   import java.lang.reflect.Array;
   29   import javax.swing.SwingUtilities;
   30   
   31   /**
   32    * An abstract class to be used in the cases where we need {@code Runnable}
   33    * to perform  some actions on an appendable set of data.
   34    * The set of data might be appended after the {@code Runnable} is
   35    * sent for the execution. Usually such {@code Runnables} are sent to
   36    * the EDT.
   37    *
   38    * <p>
   39    * Usage example:
   40    *
   41    * <p>
   42    * Say we want to implement JLabel.setText(String text) which sends
   43    * {@code text} string to the JLabel.setTextImpl(String text) on the EDT.
   44    * In the event JLabel.setText is called rapidly many times off the EDT
   45    * we will get many updates on the EDT but only the last one is important.
   46    * (Every next updates overrides the previous one.)
   47    * We might want to implement this {@code setText} in a way that only
   48    * the last update is delivered.
   49    * <p>
   50    * Here is how one can do this using {@code AccumulativeRunnable}:
   51    * <pre>
   52    * AccumulativeRunnable<String> doSetTextImpl =
   53    * new  AccumulativeRunnable<String>() {
   54    *     @Override
   55    *     protected void run(List&lt;String&gt; args) {
   56    *         //set to the last string being passed
   57    *         setTextImpl(args.get(args.size() - 1));
   58    *     }
   59    * }
   60    * void setText(String text) {
   61    *     //add text and send for the execution if needed.
   62    *     doSetTextImpl.add(text);
   63    * }
   64    * </pre>
   65    *
   66    * <p>
   67    * Say we want want to implement addDirtyRegion(Rectangle rect)
   68    * which sends this region to the
   69    * handleDirtyRegions(List<Rect> regiouns) on the EDT.
   70    * addDirtyRegions better be accumulated before handling on the EDT.
   71    *
   72    * <p>
   73    * Here is how it can be implemented using AccumulativeRunnable:
   74    * <pre>
   75    * AccumulativeRunnable<Rectangle> doHandleDirtyRegions =
   76    *     new AccumulativeRunnable<Rectangle>() {
   77    *         @Override
   78    *         protected void run(List&lt;Rectangle&gt; args) {
   79    *             handleDirtyRegions(args);
   80    *         }
   81    *     };
   82    *  void addDirtyRegion(Rectangle rect) {
   83    *      doHandleDirtyRegions.add(rect);
   84    *  }
   85    * </pre>
   86    *
   87    * @author Igor Kushnirskiy
   88    *
   89    * @param <T> the type this {@code Runnable} accumulates
   90    *
   91    * @since 1.6
   92    */
   93   public abstract class AccumulativeRunnable<T> implements Runnable {
   94       private List<T> arguments = null;
   95   
   96       /**
   97        * Equivalent to {@code Runnable.run} method with the
   98        * accumulated arguments to process.
   99        *
  100        * @param args accumulated argumets to process.
  101        */
  102       protected abstract void run(List<T> args);
  103   
  104       /**
  105        * {@inheritDoc}
  106        *
  107        * <p>
  108        * This implementation calls {@code run(List<T> args)} mehtod
  109        * with the list of accumulated arguments.
  110        */
  111       public final void run() {
  112           run(flush());
  113       }
  114   
  115       /**
  116        * appends arguments and sends this {@cod Runnable} for the
  117        * execution if needed.
  118        * <p>
  119        * This implementation uses {@see #submit} to send this
  120        * {@code Runnable} for execution.
  121        * @param args the arguments to accumulate
  122        */
  123       @SafeVarargs
  124       public final synchronized void add(T... args) {
  125           boolean isSubmitted = true;
  126           if (arguments == null) {
  127               isSubmitted = false;
  128               arguments = new ArrayList<T>();
  129           }
  130           Collections.addAll(arguments, args);
  131           if (!isSubmitted) {
  132               submit();
  133           }
  134       }
  135   
  136       /**
  137        * Sends this {@code Runnable} for the execution
  138        *
  139        * <p>
  140        * This method is to be executed only from {@code add} method.
  141        *
  142        * <p>
  143        * This implementation uses {@code SwingWorker.invokeLater}.
  144        */
  145       protected void submit() {
  146           SwingUtilities.invokeLater(this);
  147       }
  148   
  149       /**
  150        * Returns accumulated arguments and flashes the arguments storage.
  151        *
  152        * @return accumulated arguments
  153        */
  154       private final synchronized List<T> flush() {
  155           List<T> list = arguments;
  156           arguments = null;
  157           return list;
  158       }
  159   }

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