1 /*

     2  * Copyright 1996-2007 Sun Microsystems, Inc.  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.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package java.awt.event;

    27 

    28 import java.awt.AWTEvent;

    29 import java.awt.Component;

    30 import java.awt.Rectangle;

    31 

    32 /**

    33  * A low-level event which indicates that a component moved, changed

    34  * size, or changed visibility (also, the root class for the other

    35  * component-level events).

    36  * <P>

    37  * Component events are provided for notification purposes ONLY;

    38  * The AWT will automatically handle component moves and resizes

    39  * internally so that GUI layout works properly regardless of

    40  * whether a program is receiving these events or not.

    41  * <P>

    42  * In addition to serving as the base class for other component-related

    43  * events (InputEvent, FocusEvent, WindowEvent, ContainerEvent),

    44  * this class defines the events that indicate changes in

    45  * a component's size, position, or visibility.

    46  * <P>

    47  * This low-level event is generated by a component object (such as a

    48  * List) when the component is moved, resized, rendered invisible, or made

    49  * visible again. The event is passed to every <code>ComponentListener</code>

    50  * or <code>ComponentAdapter</code> object which registered to receive such

    51  * events using the component's <code>addComponentListener</code> method.

    52  * (<code>ComponentAdapter</code> objects implement the

    53  * <code>ComponentListener</code> interface.) Each such listener object

    54  * gets this <code>ComponentEvent</code> when the event occurs.

    55  *

    56  * @see ComponentAdapter

    57  * @see ComponentListener

    58  * @see <a href="http://java.sun.com/docs/books/tutorial/post1.0/ui/componentlistener.html">Tutorial: Writing a Component Listener</a>

    59  *

    60  * @author Carl Quinn

    61  * @since 1.1

    62  */

    63 public class ComponentEvent extends AWTEvent {

    64 

    65     /**

    66      * The first number in the range of ids used for component events.

    67      */

    68     public static final int COMPONENT_FIRST             = 100;

    69 

    70     /**

    71      * The last number in the range of ids used for component events.

    72      */

    73     public static final int COMPONENT_LAST              = 103;

    74 

    75    /**

    76      * This event indicates that the component's position changed.

    77      */

    78     public static final int COMPONENT_MOVED     = COMPONENT_FIRST;

    79 

    80     /**

    81      * This event indicates that the component's size changed.

    82      */

    83     public static final int COMPONENT_RESIZED   = 1 + COMPONENT_FIRST;

    84 

    85     /**

    86      * This event indicates that the component was made visible.

    87      */

    88     public static final int COMPONENT_SHOWN     = 2 + COMPONENT_FIRST;

    89 

    90     /**

    91      * This event indicates that the component was rendered invisible.

    92      */

    93     public static final int COMPONENT_HIDDEN    = 3 + COMPONENT_FIRST;

    94 

    95     /*

    96      * JDK 1.1 serialVersionUID

    97      */

    98     private static final long serialVersionUID = 8101406823902992965L;

    99 

   100     /**

   101      * Constructs a <code>ComponentEvent</code> object.

   102      * <p>Note that passing in an invalid <code>id</code> results in

   103      * unspecified behavior. This method throws an

   104      * <code>IllegalArgumentException</code> if <code>source</code>

   105      * is <code>null</code>.

   106      *

   107      * @param source the <code>Component</code> that originated the event

   108      * @param id     an integer indicating the type of event

   109      * @throws IllegalArgumentException if <code>source</code> is null

   110      */

   111     public ComponentEvent(Component source, int id) {

   112         super(source, id);

   113     }

   114 

   115     /**

   116      * Returns the originator of the event.

   117      *

   118      * @return the <code>Component</code> object that originated

   119      * the event, or <code>null</code> if the object is not a

   120      * <code>Component</code>.

   121      */

   122     public Component getComponent() {

   123         return (source instanceof Component) ? (Component)source : null;

   124     }

   125 

   126     /**

   127      * Returns a parameter string identifying this event.

   128      * This method is useful for event-logging and for debugging.

   129      *

   130      * @return a string identifying the event and its attributes

   131      */

   132     public String paramString() {

   133         String typeStr;

   134         Rectangle b = (source !=null

   135                        ? ((Component)source).getBounds()

   136                        : null);

   137 

   138         switch(id) {

   139           case COMPONENT_SHOWN:

   140               typeStr = "COMPONENT_SHOWN";

   141               break;

   142           case COMPONENT_HIDDEN:

   143               typeStr = "COMPONENT_HIDDEN";

   144               break;

   145           case COMPONENT_MOVED:

   146               typeStr = "COMPONENT_MOVED ("+

   147                          b.x+","+b.y+" "+b.width+"x"+b.height+")";

   148               break;

   149           case COMPONENT_RESIZED:

   150               typeStr = "COMPONENT_RESIZED ("+

   151                          b.x+","+b.y+" "+b.width+"x"+b.height+")";

   152               break;

   153           default:

   154               typeStr = "unknown type";

   155         }

   156         return typeStr;

   157     }

   158 }