META-INF.modules.java.desktop.classes.java.awt.event.ComponentEvent Maven / Gradle / Ivy
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package java.awt.event;
import java.awt.AWTEvent;
import java.awt.Component;
import java.awt.Rectangle;
import java.io.Serial;
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).
*
* 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 {@code ComponentListener}
* or {@code ComponentAdapter} object which registered to receive such
* events using the component's {@code addComponentListener} method.
* ({@code ComponentAdapter} objects implement the
* {@code ComponentListener} interface.) Each such listener object
* gets this {@code ComponentEvent} when the event occurs.
*
* 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 Tutorial: Writing a Component Listener
*
* @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;
/**
* Use serialVersionUID from JDK 1.1 for interoperability.
*/
@Serial
private static final long serialVersionUID = 8101406823902992965L;
/**
* Constructs a {@code ComponentEvent} object.
*
This method throws an
* {@code IllegalArgumentException} if {@code source}
* is {@code null}.
*
* @param source The {@code Component} 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} 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} object that originated
* the event, or {@code null} if the object is not a
* {@code 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;
}
}