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* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*/
package java.awt.event;
import java.awt.
AWTEvent;
import java.awt.
Component;
import java.awt.
Rectangle;
import java.lang.annotation.
Native;
/**
* 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).
* <P>
* 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.
* <P>
* 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.
* <P>
* 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 <code>ComponentListener</code>
* or <code>ComponentAdapter</code> object which registered to receive such
* events using the component's <code>addComponentListener</code> method.
* (<code>ComponentAdapter</code> objects implement the
* <code>ComponentListener</code> interface.) Each such listener object
* gets this <code>ComponentEvent</code> when the event occurs.
* <p>
* An unspecified behavior will be caused if the {@code id} parameter
* of any particular {@code ComponentEvent} instance is not
* in the range from {@code COMPONENT_FIRST} to {@code COMPONENT_LAST}.
*
* @see ComponentAdapter
* @see ComponentListener
* @see <a href="https://docs.oracle.com/javase/tutorial/uiswing/events/componentlistener.html">Tutorial: Writing a Component Listener</a>
*
* @author Carl Quinn
* @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.
*/
@
Native public static final int
COMPONENT_MOVED =
COMPONENT_FIRST;
/**
* This event indicates that the component's size changed.
*/
@
Native public static final int
COMPONENT_RESIZED = 1 +
COMPONENT_FIRST;
/**
* This event indicates that the component was made visible.
*/
@
Native public static final int
COMPONENT_SHOWN = 2 +
COMPONENT_FIRST;
/**
* This event indicates that the component was rendered invisible.
*/
@
Native public static final int
COMPONENT_HIDDEN = 3 +
COMPONENT_FIRST;
/*
* JDK 1.1 serialVersionUID
*/
private static final long
serialVersionUID = 8101406823902992965L;
/**
* Constructs a <code>ComponentEvent</code> object.
* <p> This method throws an
* <code>IllegalArgumentException</code> if <code>source</code>
* is <code>null</code>.
*
* @param source The <code>Component</code> that originated the event
* @param id An integer indicating the type of event.
* For information on allowable values, see
* the class description for {@link ComponentEvent}
* @throws IllegalArgumentException if <code>source</code> is null
* @see #getComponent()
* @see #getID()
*/
public
ComponentEvent(
Component source, int
id) {
super(
source,
id);
}
/**
* Returns the originator of the event.
*
* @return the <code>Component</code> object that originated
* the event, or <code>null</code> if the object is not a
* <code>Component</code>.
*/
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;
}
}