libjava/java/awt/event/ComponentEvent.java

   1 /* ComponentEvent.java -- notification of events for components
   2    Copyright (C) 1999, 2002 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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.event;
  40
  41 import java.awt.AWTEvent;
  42 import java.awt.Component;
  43
  44 /**
  45  * This class is for events generated when a component is moved, resized,
  46  * hidden, or shown.  These events normally do not need to be handled by the
  47  * application, since the AWT system automatically takes care of them. This
  48  * is also the superclass for other events on components, but
  49  * ComponentListeners ignore such subclasses.
  50  *
  51  * @author Aaron M. Renn <arenn@urbanophile.com>
  52  * @see ComponentAdapter
  53  * @see ComponentListener
  54  * @since 1.1
  55  * @status updated to 1.4
  56  */
  57 public class ComponentEvent extends AWTEvent
  58 {
  59   /**
  60    * Compatible with JDK 1.1+.
  61    */
  62   private static final long serialVersionUID = 8101406823902992965L;
  63
  64   /** This is the first id in the range of ids used by this class. */
  65   public static final int COMPONENT_FIRST = 100;
  66
  67   /** This is the last id in the range of ids used by this class. */
  68   public static final int COMPONENT_LAST = 103;
  69
  70   /** This id indicates that a component was moved. */
  71   public static final int COMPONENT_MOVED = 100;
  72
  73   /** This id indicates that a component was resized. */
  74   public static final int COMPONENT_RESIZED = 101;
  75
  76   /** This id indicates that a component was shown. */
  77   public static final int COMPONENT_SHOWN = 102;
  78
  79   /** This id indicates that a component was hidden. */
  80   public static final int COMPONENT_HIDDEN = 103;
  81
  82   /**
  83    * Initializes a new instance of <code>ComponentEvent</code> with the
  84    * specified source and id. Note that an invalid id leads to unspecified
  85    * results.
  86    *
  87    * @param source the source of the event
  88    * @param id the event id
  89    * @throws IllegalArgumentException if source is null
  90    */
  91   public ComponentEvent(Component source, int id)
  92   {
  93     super(source, id);
  94   }
  95
  96   /**
  97    * This method returns the event source as a <code>Component</code>. If the
  98    * source has subsequently been modified to a non-Component, this returns
  99    * null.
 100    *
 101    * @return the event source as a <code>Component</code>, or null
 102    */
 103   public Component getComponent()
 104   {
 105     return source instanceof Component ? (Component) source : null;
 106   }
 107
 108   /**
 109    * This method returns a string identifying this event. This is the field
 110    * name of the id type, and for COMPONENT_MOVED or COMPONENT_RESIZED, the
 111    * new bounding box of the component.
 112    *
 113    * @return a string identifying this event
 114    */
 115   public String paramString()
 116   {
 117     // Unlike Sun, we don't throw NullPointerException or ClassCastException
 118     // when source was illegally changed.
 119     switch (id)
 120       {
 121       case COMPONENT_MOVED:
 122         return "COMPONENT_MOVED "
 123           + (source instanceof Component
 124              ? ((Component) source).getBounds() : (Object) "");
 125       case COMPONENT_RESIZED:
 126         return "COMPONENT_RESIZED "
 127           + (source instanceof Component
 128              ? ((Component) source).getBounds() : (Object) "");
 129       case COMPONENT_SHOWN:
 130         return "COMPONENT_SHOWN";
 131       case COMPONENT_HIDDEN:
 132         return "COMPONENT_HIDDEN";
 133       default:
 134         return "unknown type";
 135       }
 136   }
 137 } // class ComponentEvent