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/* * @(#)Component.java 1.347 02/05/03 * * Copyright 2002 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.awt; import java.io.PrintStream; import java.io.PrintWriter; import java.util.Vector; import java.util.Locale; import java.util.EventListener; import java.util.Iterator; import java.util.HashSet; import java.util.Set; import java.util.Collections; import java.awt.peer.ComponentPeer; import java.awt.peer.ContainerPeer; import java.awt.peer.LightweightPeer; import java.awt.image.BufferStrategy; import java.awt.image.ImageObserver; import java.awt.image.ImageProducer; import java.awt.image.ColorModel; import java.awt.image.VolatileImage; import java.awt.event.*; import java.awt.datatransfer.Transferable; import java.awt.dnd.DnDConstants; import java.awt.dnd.DragSource; import java.awt.dnd.DragSourceContext; import java.awt.dnd.DragSourceListener; import java.awt.dnd.InvalidDnDOperationException; import java.io.Serializable; import java.io.ObjectOutputStream; import java.io.ObjectInputStream; import java.io.IOException; import java.beans.PropertyChangeListener; import java.awt.event.InputMethodListener; import java.awt.event.InputMethodEvent; import java.awt.im.InputContext; import java.awt.im.InputMethodRequests; import java.awt.dnd.DropTarget; import javax.accessibility.*; import java.awt.GraphicsConfiguration; import javax.accessibility.*; import sun.security.action.GetPropertyAction; import sun.awt.AppContext; import sun.awt.SunToolkit; import sun.awt.ConstrainableGraphics; import sun.awt.DebugHelper; import sun.awt.WindowClosingListener; import sun.awt.WindowClosingSupport; import sun.awt.GlobalCursorManager; import sun.awt.dnd.SunDropTargetEvent; import sun.awt.im.CompositionArea; /** * A <em>component</em> is an object having a graphical representation * that can be displayed on the screen and that can interact with the * user. Examples of components are the buttons, checkboxes, and scrollbars * of a typical graphical user interface. <p> * The <code>Component</code> class is the abstract superclass of * the nonmenu-related Abstract Window Toolkit components. Class * <code>Component</code> can also be extended directly to create a * lightweight component. A lightweight component is a component that is * not associated with a native opaque window. * <p> * <h3>Serialization</h3> * It is important to note that only AWT listeners which conform * to the <code>Serializable</code> protocol will be saved when * the object is stored. If an AWT object has listeners that * aren't marked serializable, they will be dropped at * <code>writeObject</code> time. Developers will need, as always, * to consider the implications of making an object serializable. * One situation to watch out for is this: * <pre> * import java.awt.*; * import java.awt.event.*; * import java.io.Serializable; * * class MyApp implements ActionListener, Serializable * { * BigObjectThatShouldNotBeSerializedWithAButton bigOne; * Button aButton = new Button(); * * MyApp() * { * // Oops, now aButton has a listener with a reference * // to bigOne! * aButton.addActionListener(this); * } * * public void actionPerformed(ActionEvent e) * { * System.out.println("Hello There"); * } * } * </pre> * In this example, serializing <code>aButton</code> by itself * will cause <code>MyApp</code> and everything it refers to * to be serialized as well. The problem is that the listener * is serializable by coincidence, not by design. To separate * the decisions about <code>MyApp</code> and the * <code>ActionListener</code> being serializable one can use a * nested class, as in the following example: * <pre> * import java.awt.*; * import java.awt.event.*; * import java.io.Serializable; * * class MyApp java.io.Serializable * { * BigObjectThatShouldNotBeSerializedWithAButton bigOne; * Button aButton = new Button(); * * class MyActionListener implements ActionListener * { * public void actionPerformed(ActionEvent e) * { * System.out.println("Hello There"); * } * } * * MyApp() * { * aButton.addActionListener(new MyActionListener()); * } * } * </pre> * <p> * <b>Note</b>: For more information on the paint mechanisms utilitized * by AWT and Swing, including information on how to write the most * efficient painting code, see * <a href="http://java.sun.com/products/jfc/tsc/articles/painting/index.html">Painting in AWT and Swing</a>. * * @version 1.347, 05/03/02 * @author Arthur van Hoff * @author Sami Shaio */ public abstract class Component implements ImageObserver, MenuContainer, Serializable { /** * The peer of the component. The peer implements the component's * behavior. The peer is set when the <code>Component</code> is * added to a container that also is a peer. * @see #addNotify * @see #removeNotify */ transient ComponentPeer peer; /** * The parent of the object. It may be <code>null</code> * for top-level components. * @see #getParent */ transient Container parent; /** * The <code>AppContext</code> of the component. This is set in * the constructor and never changes. */ transient AppContext appContext; /** * The x position of the component in the parent's coordinate system. * * @serial * @see #getLocation */ int x; /** * The y position of the component in the parent's coordinate system. * * @serial * @see #getLocation */ int y; /** * The width of the component. * * @serial * @see #getSize */ int width; /** * The height of the component. * * @serial * @see #getSize */ int height; /** * The foreground color for this component. * <code>foreground</code> can be <code>null</code>. * * @serial * @see #getForeground * @see #setForeground */ Color foreground; /** * The background color for this component. * <code>background</code> can be <code>null</code>. * * @serial * @see #getBackground * @see #setBackground */ Color background; /** * The font used by this component. * The <code>font</code> can be <code>null</code>. * * @serial * @see #getFont * @see #setFont */ Font font; /** * The font which the peer is currently using. * (<code>null</code> if no peer exists.) */ Font peerFont; /** * The cursor displayed when pointer is over this component. * This value can be <code>null</code>. * * @serial * @see #getCursor * @see #setCursor */ Cursor cursor; /** * The locale for the component. * * @serial * @see #getLocale * @see #setLocale */ Locale locale; /** * A reference to a <code>GraphicsConfiguration</code> object * used to describe the characteristics of a graphics * destination. * This value can be <code>null</code>. * * @since 1.3 * @serial * @see GraphicsConfiguration * @see #getGraphicsConfiguration */ transient GraphicsConfiguration graphicsConfig = null; /** * A reference to a <code>BufferStrategy</code> object * used to manipulate the buffers on this component. * * @since 1.4 * @see java.awt.image.BufferStrategy * @see #getBufferStrategy */ transient BufferStrategy bufferStrategy = null; /** * True when the object should ignore all repaint events. * * @since 1.4