001    /* ComponentEvent.java -- notification of events for components
002       Copyright (C) 1999, 2002, 2005, 2006  Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package java.awt.event;
040    
041    import java.awt.AWTEvent;
042    import java.awt.Component;
043    
044    /**
045     * This class is for events generated when a component is moved, resized,
046     * hidden, or shown.  These events normally do not need to be handled by the
047     * application, since the AWT system automatically takes care of them. This
048     * is also the superclass for other events on components, but
049     * ComponentListeners ignore such subclasses.
050     *
051     * @author Aaron M. Renn (arenn@urbanophile.com)
052     * @see ComponentAdapter
053     * @see ComponentListener
054     * @since 1.1
055     * @status updated to 1.4
056     */
057    public class ComponentEvent extends AWTEvent
058    {
059      /**
060       * Compatible with JDK 1.1+.
061       */
062      private static final long serialVersionUID = 8101406823902992965L;
063    
064      /** This is the first id in the range of ids used by this class. */
065      public static final int COMPONENT_FIRST = 100;
066    
067      /** This is the last id in the range of ids used by this class. */
068      public static final int COMPONENT_LAST = 103;
069    
070      /** This id indicates that a component was moved. */
071      public static final int COMPONENT_MOVED = 100;
072    
073      /** This id indicates that a component was resized. */
074      public static final int COMPONENT_RESIZED = 101;
075    
076      /** This id indicates that a component was shown. */
077      public static final int COMPONENT_SHOWN = 102;
078    
079      /** This id indicates that a component was hidden. */
080      public static final int COMPONENT_HIDDEN = 103;
081    
082      /**
083       * Initializes a new instance of <code>ComponentEvent</code> with the
084       * specified source and id. Note that an invalid id leads to unspecified
085       * results.
086       *
087       * @param source the source of the event
088       * @param id the event id
089       * @throws IllegalArgumentException if source is null
090       */
091      public ComponentEvent(Component source, int id)
092      {
093        super(source, id);
094      }
095    
096      /**
097       * This method returns the event source as a <code>Component</code>. If the
098       * source has subsequently been modified to a non-Component, this returns
099       * 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        StringBuffer s = new StringBuffer();
118        
119        // Unlike Sun, we don't throw NullPointerException or ClassCastException
120        // when source was illegally changed.
121        if (id == COMPONENT_MOVED)
122          s.append("COMPONENT_MOVED ");
123        else if (id == COMPONENT_RESIZED) 
124          s.append("COMPONENT_RESIZED ");
125        else if (id == COMPONENT_SHOWN)
126          s.append("COMPONENT_SHOWN ");
127        else if (id == COMPONENT_HIDDEN)
128          s.append("COMPONENT_HIDDEN ");
129        else
130          return "unknown type";
131    
132        s.append("(").append(getComponent().getX()).append(",")
133          .append(getComponent().getY()).append(" ")
134          .append(getComponent().getWidth()).append("x")
135          .append(getComponent().getHeight()).append(")");
136    
137        return s.toString();
138      }
139      
140    } // class ComponentEvent