/* * @(#)ComponentEvent.java 1.27 03/12/19 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.awt.event; import java.awt.AWTEvent; import java.awt.Event; import java.awt.Component; import java.awt.Rectangle; /** * A low-level event which indicates that a component moved, changed * size, or changed visibility (also, the root class for the other * component-level events). *
* Component events are provided for notification purposes ONLY; * The AWT will automatically handle component moves and resizes * internally so that GUI layout works properly regardless of * whether a program is receiving these events or not. *
* In addition to serving as the base class for other component-related * events (InputEvent, FocusEvent, WindowEvent, ContainerEvent), * this class defines the events that indicate changes in * a component's size, position, or visibility. *
* This low-level event is generated by a component object (such as a
* List) when the component is moved, resized, rendered invisible, or made
* visible again. The event is passed to every ComponentListener
* or ComponentAdapter
object which registered to receive such
* events using the component's addComponentListener
method.
* (ComponentAdapter
objects implement the
* ComponentListener
interface.) Each such listener object
* gets this ComponentEvent
when the event occurs.
*
* @see ComponentAdapter
* @see ComponentListener
* @see Tutorial: Writing a Component Listener
* @see Reference: The Java Class Libraries (update file)
*
* @author Carl Quinn
* @version 1.27 12/19/03
* @since 1.1
*/
public class ComponentEvent extends AWTEvent {
/**
* The first number in the range of ids used for component events.
*/
public static final int COMPONENT_FIRST = 100;
/**
* The last number in the range of ids used for component events.
*/
public static final int COMPONENT_LAST = 103;
/**
* This event indicates that the component's position changed.
*/
public static final int COMPONENT_MOVED = COMPONENT_FIRST;
/**
* This event indicates that the component's size changed.
*/
public static final int COMPONENT_RESIZED = 1 + COMPONENT_FIRST;
/**
* This event indicates that the component was made visible.
*/
public static final int COMPONENT_SHOWN = 2 + COMPONENT_FIRST;
/**
* This event indicates that the component was rendered invisible.
*/
public static final int COMPONENT_HIDDEN = 3 + COMPONENT_FIRST;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = 8101406823902992965L;
/**
* Constructs a ComponentEvent
object.
*
Note that passing in an invalid id
results in
* unspecified behavior. This method throws an
* IllegalArgumentException
if source
* is null
.
*
* @param source the Component
that originated the event
* @param id an integer indicating the type of event
* @throws IllegalArgumentException if source
is null
*/
public ComponentEvent(Component source, int id) {
super(source, id);
}
/**
* Returns the originator of the event.
*
* @return the Component
object that originated
* the event, or null
if the object is not a
* Component
.
*/
public Component getComponent() {
return (source instanceof Component) ? (Component)source : null;
}
/**
* Returns a parameter string identifying this event.
* This method is useful for event-logging and for debugging.
*
* @return a string identifying the event and its attributes
*/
public String paramString() {
String typeStr;
Rectangle b = (source !=null
? ((Component)source).getBounds()
: null);
switch(id) {
case COMPONENT_SHOWN:
typeStr = "COMPONENT_SHOWN";
break;
case COMPONENT_HIDDEN:
typeStr = "COMPONENT_HIDDEN";
break;
case COMPONENT_MOVED:
typeStr = "COMPONENT_MOVED ("+
b.x+","+b.y+" "+b.width+"x"+b.height+")";
break;
case COMPONENT_RESIZED:
typeStr = "COMPONENT_RESIZED ("+
b.x+","+b.y+" "+b.width+"x"+b.height+")";
break;
default:
typeStr = "unknown type";
}
return typeStr;
}
}