Apple Developer Connection Student Program/ADC Tools Sampler CD Disk 3 1999.iso/Metrowerks CodeWarrior/Java Support/Java_Source/Java2/src/java/awt/Window.java

Java Source | 1999-05-28 | 31.6 KB | 1,070 lines | [TEXT/CWIE]

/*
 * @(#)Window.java    1.106 98/10/27
 *
 * Copyright 1995-1998 by Sun Microsystems, Inc.,
 * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information
 * of Sun Microsystems, Inc. ("Confidential Information").  You
 * shall not disclose such Confidential Information and shall use
 * it only in accordance with the terms of the license agreement
 * you entered into with Sun.
 */
package java.awt;

import java.awt.peer.WindowPeer;
import java.awt.event.*;
import java.util.Vector;
import java.util.Locale;
import java.io.Serializable;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;
import java.io.OptionalDataException;
import java.awt.im.InputContext;
import java.util.ResourceBundle;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import java.security.AccessController;
import sun.security.action.GetPropertyAction;

/**
 * A <code>Window</code> object is a top-level window with no borders and no
 * menubar.
 * The default layout for a window is <code>BorderLayout</code>.
 * <p>
 * A window must have either a frame, dialog, or another window defined as its
 * owner when it's constructed.
 * <p>
 * Windows are capable of generating the following window events:
 * WindowOpened, WindowClosed.
 *
 * @version     1.106, 10/27/98
 * @author     Sami Shaio
 * @author     Arthur van Hoff
 * @see WindowEvent
 * @see #addWindowListener
 * @see java.awt.BorderLayout
 * @since       JDK1.0
 */
public class Window extends Container {

    /**
     * This represents the warning message that is
     * to be displayed in a non secure window. ie :
     * a window that has a security manager installed for
     * which calling SecurityManager.checkTopLevelWindow()
     * is false.  This message can be displayed anywhere in
     * the window.
     *
     * @serial
     * @see getWarningString()
     */
    String      warningString;

    static final int OPENED = 0x01;

    /**
     * An Integer value representing the Window State.
     *
     * @serial
     * @since JDK1.2
     * @see show()
     */
    int state;

    /**
     * A vector containing all the windows this
     * window currently owns.
     * @since JDK1.2
     * @see getOwnedWindows()
     */
    transient Vector ownedWindowList;
    private transient WeakReference weakThis;

    transient WindowListener windowListener;
    private transient boolean active = false;   // == true when Window receives WINDOW_ACTIVATED event
                                                // == false when Window receives WINDOW_DEACTIVATED event

    transient InputContext inputContext;

    /**
     * The Focus for the Window in question, and its components.
     *
     * @serial
     * @since JDK1.2
     * @See java.awt.FocusManager
     */
    private FocusManager focusMgr;

    private static final String base = "win";
    private static int nameCounter = 0;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = 4497834738069338734L;


    static {
        /* ensure that the necessary native libraries are loaded */
    Toolkit.loadLibraries();
    initIDs();
    }

    /**
     * Initialize JNI field and method IDs for fields that may be
       accessed from C.
     */
    private static native void initIDs();

    /**
     * Constructs a new window.
     *
     * <p>First, if there is a security manager, its
     * <code>checkTopLevelWindow</code>
     * method is called with <code>this</code>
     * as its argument
     * to see if it's ok to display the window without a warning banner.
     * If the default implementation of <code>checkTopLevelWindow</code>
     * is used (that is, that method is not overriden), then this results in
     * a call to the security manager's <code>checkPermission</code> method with an
     * <code>AWTPermission("showWindowWithoutWarningBanner")<code>
     * permission. It that method raises a SecurityException,
     * <code>checkTopLevelWindow</code> returns false, otherwise it
     * returns true. If it returns false, a warning banner is created.
     *
     * @see java.lang.SecurityManager#checkTopLevelWindow
     */
    Window() {
    setWarningString();
    this.focusMgr = new FocusManager(this);
    this.visible = false;
    this.inputContext = InputContext.getInstance();
    }

    /**
     * Constructs a new invisible window.
     * <p>
     * The window is not initially visible. Call the <code>show</code>
     * method to cause the window to become visible.
     * <p>
     * If there is a security manager, this method first calls
     * the security manager's <code>checkTopLevelWindow</code>
     * method with <code>this</code>
     * as its argument to determine whether or not the window
     * must be displayed with a warning banner.
     *
     * @param     owner   the main application frame.
     * @exception java.lang.IllegalArgumentException if <code>owner</code>
     *            is <code>null</code>
     * @see       java.awt.Window#show
     * @see       java.awt.Component#setSize
     * @see       java.lang.SecurityManager#checkTopLevelWindow
     */
    public Window(Frame owner) {
    this();
    ownedInit(owner);
    }

    /**
     * Constructs a new invisible window with the specified
     * window as its owner.
     * <p>
     * If there is a security manager, this method first calls
     * the security manager's <code>checkTopLevelWindow</code>
     * method with <code>this</code>
     * as its argument to determine whether or not the window
     * must be displayed with a warning banner.
     *
     * @param     owner   the window to act as owner
     * @exception java.lang.IllegalArgumentException if <code>owner</code>
     *            is <code>null</code>
     * @see       java.lang.SecurityManager#checkTopLevelWindow
     * @since     JDK1.2
     */
    public Window(Window owner) {
    this();
    ownedInit(owner);
    }

    private void ownedInit(Window owner) {
    if (owner == null) {
        throw new IllegalArgumentException("null owner window");
    }
    this.parent = owner;
    this.weakThis = new WeakReference(this);
    owner.addOwnedWindow(weakThis);
    setLayout(new BorderLayout());
    }

    /**
     * Disposes of the input methods and context, and removes the WeakReference
     * which formerly pointed to this Window from the parent's owned Window
     * list.
     */
    protected void finalize() throws Throwable {
        inputContext.dispose();
    if (parent != null) {
        ((Window)parent).removeOwnedWindow(weakThis);
    }
    super.finalize();
    }

    /**
     * Construct a name for this component.  Called by getName() when the
     * name is null.
     */
    String constructComponentName() {
        synchronized (getClass()) {
        return base + nameCounter++;
    }
    }

    /**
     * Makes this Window displayable by creating the connection to its
     * native screen resource.
     * This method is called internally by the toolkit and should
     * not be called directly by programs.
     * @see Component#isDisplayable
     * @see Container#removeNotify
     * @since JDK1.0
     */
    public void addNotify() {
    synchronized (getTreeLock()) {
        if (peer == null)
        peer = getToolkit().createWindow(this);
        super.addNotify();
    }
    }

    /**
     * Causes this Window to be sized to fit the preferred size
     * and layouts of its subcomponents.  If the window and/or its owner
     * are not yet displayable, both are made displayable before
     * calculating the preferred size.  The Window will be validated
     * after the preferredSize is calculated.
     * @see Component#isDisplayable
     */
    public void pack() {
    Container parent = this.parent;
    if (parent != null && parent.getPeer() == null) {
        parent.addNotify();
    }
    if (peer == null) {
        addNotify();
    }
    setSize(getPreferredSize());
    isPacked = true;

    validate();
    }

    /**
     * Makes the Window visible. If the Window and/or its owner
     * are not yet displayable, both are made displayable.  The
     * Window will be validated prior to being made visible.
     * If the Window is already visible, this will bring the Window
     * to the front.
     * @see       java.awt.Component#isDisplayable
     * @see       java.awt.Window#toFront
     * @see       java.awt.Component#setVisible
     */
    public void show() {
        Container parent = this.parent;
    if (parent != null && parent.getPeer() == null) {
        parent.addNotify();
    }
    if (peer == null) {
        addNotify();
    }
    validate();

    if (visible) {
        toFront();
    } else {
        super.show();
    }

        // If first time shown, generate WindowOpened event
        if ((state & OPENED) == 0) {
            postWindowEvent(WindowEvent.WINDOW_OPENED);
            state |= OPENED;
        }
    }

    synchronized void postWindowEvent(int id) {
        if (windowListener != null ||
            (eventMask & AWTEvent.WINDOW_EVENT_MASK) != 0) {
            WindowEvent e = new WindowEvent(this, id);
            Toolkit.getEventQueue().postEvent(e);
        }
    }

    /**
     * Releases all of the native screen resources used by this Window and
     * its subcomponents. That is, the resources for the Window, all of its
     * contained children, and all of its owned Windows will be destroyed,
     * and any memory they consume returned to the OS. The Window and all of
     * its subcomponents will be marked as undisplayable.
     * <p>
     * The Window and its subcomponents can be made displayable again
     * by rebuilding the native resources with a subsequent call to
     * <code>pack</code> or <code>show</code>. The states of the recreated
     * Window and its subcomponents will be identical to the states of these
     * objects at the point where the Window was disposed (not accounting for
     * additional modifcations between those actions).
     * </p>
     * @see Component#isDisplayable
     * @see Window#getOwnedWindows
     * @see Window#pack
     * @see Window#show
     */
    public void dispose() {
        class DisposeAction implements Runnable {
        public void run() {
            if (ownedWindowList != null) {
            synchronized (ownedWindowList) {
                for (int i = 0; i < ownedWindowList.size(); i++) {
                Window child = (Window) (((WeakReference)
                    (ownedWindowList.elementAt(i))).get());
                if (child != null) {
                    child.dispose();
                }
            }
            }
        }
        hide();
        removeNotify();
        }
    }

    DisposeAction action = new DisposeAction();
    if (EventQueue.isDispatchThread()) {
        action.run();
    }
    else {
        try {
            EventQueue.invokeAndWait(action);
        }
        catch (InterruptedException e) {
            System.err.println("Disposal was interrupted:");
        e.printStackTrace();
        }
        catch (InvocationTargetException e) {
            System.err.println("Exception during disposal:");
        e.printStackTrace();
        }
    }
    // Execute outside the Runnable because postWindowEvent is
    // synchronized on (this). We don't need to synchronize the call
    // on the EventQueue anyways.
    postWindowEvent(WindowEvent.WINDOW_CLOSED);
    }

    /**
     * Brings this window to the front.
     * Places this window at the top of the stacking order and
     * shows it in front of any other windows.
     * @see       java.awt.Window#toBack
     */
    public void toFront() {
        WindowPeer peer = (WindowPeer)this.peer;
    if (peer != null) {
        peer.toFront();
    }
    }

    /**
     * Sends this window to the back.
     * Places this window at the bottom of the stacking order and
     * makes the corresponding adjustment to other visible windows.
     * @see       java.awt.Window#toFront
     */
    public void toBack() {
        WindowPeer peer = (WindowPeer)this.peer;
    if (peer != null) {
        peer.toBack();
    }
    }

    /**
     * Returns the toolkit of this frame.
     * @return    the toolkit of this window.
     * @see       java.awt.Toolkit
     * @see       java.awt.Toolkit#getDefaultToolkit()
     * @see       java.awt.Component#getToolkit()
     */
    public Toolkit getToolkit() {
    return Toolkit.getDefaultToolkit();
    }

    /**
     * Gets the warning string that is displayed with this window.
     * If this window is insecure, the warning string is displayed
     * somewhere in the visible area of the window. A window is
     * insecure if there is a security manager, and the security
     * manager's <code>checkTopLevelWindow</code> method returns
     * <code>false</code> when this window is passed to it as an
     * argument.
     * <p>
     * If the window is secure, then <code>getWarningString</code>
     * returns <code>null</code>. If the window is insecure, this
     * method checks for the system property
     * <code>awt.appletWarning</code>
     * and returns the string value of that property.
     * @return    the warning string for this window.
     * @see       java.lang.SecurityManager#checkTopLevelWindow(java.lang.Object)
     */
    public final String getWarningString() {
    return warningString;
    }

    private void setWarningString() {
    warningString = null;
    SecurityManager sm = System.getSecurityManager();
    if (sm != null) {
        if (!sm.checkTopLevelWindow(this)) {
        // make sure the privileged action is only
        // for getting the property! We don't want the
        // above checkTopLevelWindow call to always succeed!
        warningString = (String) AccessController.doPrivileged(
              new GetPropertyAction("awt.appletWarning",
                        "Warning: Applet Window"));
        }
    }
    }

    /**
     * Gets the <code>Locale</code> object that is associated
     * with this window, if the locale has been set.
     * If no locale has been set, then the default locale
     * is returned.
     * @return    the locale that is set for this window.
     * @see       java.util.Locale
     * @since     JDK1.1
     */

    public Locale getLocale() {
      if (this.locale == null) {
    return Locale.getDefault();
      }
      return this.locale;
    }

    /**
     * Gets the input context for this window. A window always has an input context,
     * which is shared by subcomponents unless they create and set their own.
     * @see Component#getInputContext
     * @since JDK1.2
     */

    public InputContext getInputContext() {
        return inputContext;
    }

    /**
     * Returns the owner of this window.
     */
    public Window getOwner() {
        return (Window)parent;
    }

    /**
     * Return an array containing all the windows this
     * window currently owns.
     * @since JDK1.2
     */
    public Window[] getOwnedWindows() {
        Window realCopy[];
        if (ownedWindowList != null) {
            synchronized(ownedWindowList) {
            // Recall that ownedWindowList is actually a Vector of
            // WeakReferences and calling get() on one of these references
            // may return null. Make two arrays-- one the size of the
            // Vector (fullCopy with size fullSize), and one the size of
            // all non-null get()s (realCopy with size realSize).
                int fullSize = ownedWindowList.size();
                int realSize = 0;
                Window fullCopy[] = new Window[fullSize];

                for (int i = 0; i < fullSize; i++) {
                    fullCopy[realSize] = (Window) (((WeakReference)
                        (ownedWindowList.elementAt(i))).get());

                    if (fullCopy[realSize] != null) {
                        realSize++;
                    }
                }

        if (fullSize != realSize) {
            realCopy = new Frame[realSize];
            System.arraycopy(fullCopy, 0, realCopy, 0, realSize);
        } else {
            realCopy = fullCopy;
        }
        }
    } else {
        realCopy = new Window[0];
    }
        return realCopy;
    }

    /**
     * Adds the specified window listener to receive window events from
     * this window.
     * If l is null, no exception is thrown and no action is performed.
     *
     * @param     l the window listener
     */
    public synchronized void addWindowListener(WindowListener l) {
    if (l == null) {
        return;
    }
        windowListener = AWTEventMulticaster.add(windowListener, l);
        newEventsOnly = true;
    }

    /**
     * Removes the specified window listener so that it no longer
     * receives window events from this window.
     * If l is null, no exception is thrown and no action is performed.
     *
     * @param     l the window listener
     */
    public synchronized void removeWindowListener(WindowListener l) {
    if (l == null) {
        return;
    }
        windowListener = AWTEventMulticaster.remove(windowListener, l);
    }

    // REMIND: remove when filtering is handled at lower level
    boolean eventEnabled(AWTEvent e) {
        switch(e.id) {
          case WindowEvent.WINDOW_OPENED:
          case WindowEvent.WINDOW_CLOSING:
          case WindowEvent.WINDOW_CLOSED:
          case WindowEvent.WINDOW_ICONIFIED:
          case WindowEvent.WINDOW_DEICONIFIED:
          case WindowEvent.WINDOW_ACTIVATED:
          case WindowEvent.WINDOW_DEACTIVATED:
            if ((eventMask & AWTEvent.WINDOW_EVENT_MASK) != 0 ||
                windowListener != null) {
                return true;
            }
            return false;
          default:
            break;
        }
        return super.eventEnabled(e);
    }

    boolean isActive() {
    return active;
    }

    /**
     * Processes events on this window. If the event is an WindowEvent,
     * it invokes the processWindowEvent method, else it invokes its
     * superclass's processEvent.
     * @param e the event
     */
    protected void processEvent(AWTEvent e) {
        if (e instanceof WindowEvent) {
            processWindowEvent((WindowEvent)e);
            return;
        }
    super.processEvent(e);
    }

    /**
     * Processes window events occurring on this window by
     * dispatching them to any registered WindowListener objects.
     * NOTE: This method will not be called unless window events
     * are enabled for this component; this happens when one of the
     * following occurs:
     * a) A WindowListener object is registered via addWindowListener()
     * b) Window events are enabled via enableEvents()
     * @see Component#enableEvents
     * @param e the window event
     */
    protected void processWindowEvent(WindowEvent e) {
        if (windowListener != null) {
            switch(e.getID()) {
              case WindowEvent.WINDOW_OPENED:
                windowListener.windowOpened(e);
                break;
              case WindowEvent.WINDOW_CLOSING:
                windowListener.windowClosing(e);
                break;
              case WindowEvent.WINDOW_CLOSED:
                windowListener.windowClosed(e);
                break;
              case WindowEvent.WINDOW_ICONIFIED:
                windowListener.windowIconified(e);
                break;
              case WindowEvent.WINDOW_DEICONIFIED:
                windowListener.windowDeiconified(e);
                break;
              case WindowEvent.WINDOW_ACTIVATED:
                windowListener.windowActivated(e);
                break;
              case WindowEvent.WINDOW_DEACTIVATED:
                windowListener.windowDeactivated(e);
                break;
              default:
                break;
            }
        }
    }

    void preProcessKeyEvent(KeyEvent e) {
        // Dump the list of child windows to System.out.
        if (e.isActionKey() && e.getKeyCode() == KeyEvent.VK_F1 &&
            e.isControlDown() && e.isShiftDown() &&
            e.getID() == KeyEvent.KEY_PRESSED) {
            list(System.out, 0);
        }
    }

    void postProcessKeyEvent(KeyEvent e) {
        WindowPeer    peer = (WindowPeer)this.peer;
        if (peer == null)
            return;

      switch(peer.handleFocusTraversalEvent(e)) {
    case WindowPeer.IGNORE_EVENT:
    default:
        break;
    case WindowPeer.CONSUME_EVENT:
        e.consume();
        break;
    case WindowPeer.FOCUS_NEXT:
        if (focusMgr.focusNext())
        e.consume();
        break;
    case WindowPeer.FOCUS_PREVIOUS:
        if (focusMgr.focusPrevious())
        e.consume();
        break;
    }

    return;
    }

    void setFocusOwner(Component c) {
    focusMgr.setFocusOwner(c);
    }

    void transferFocus(Component base) {
    nextFocus(base);
    }

    /**
     * Returns the child component of this Window which has focus if and
     * only if this Window is active.
     * @return the component with focus, or null if no children have focus
     * assigned to them.
     */
    public Component getFocusOwner() {
        if (active)
            return focusMgr.getFocusOwner();
        else
            return null;
    }

    /**
     * @deprecated As of JDK version 1.1,
     * replaced by <code>transferFocus(Component)</code>.
     */
    void nextFocus(Component base) {
    focusMgr.focusNext(base);
    }

    /*
     * Dispatches an event to this window or one of its sub components.
     * @param e the event
     */
    void dispatchEventImpl(AWTEvent e) {
        switch(e.getID()) {
          case FocusEvent.FOCUS_GAINED:
            setFocusOwner(this);
            break;
          case ComponentEvent.COMPONENT_RESIZED:
            invalidate();
            validate();
            repaint();
            break;
          case WindowEvent.WINDOW_ACTIVATED:
            active = true;
/*
  Calling this messes up focus on Solaris

            focusMgr.activateFocus();
*/
            break;
          case WindowEvent.WINDOW_DEACTIVATED:
            active = false;
            break;
          default:
            break;
        }
        super.dispatchEventImpl(e);
    }

    /**
     * @deprecated As of JDK version 1.1
     * replaced by <code>dispatchEvent(AWTEvent)</code>.
     */
    public boolean postEvent(Event e) {
        if (handleEvent(e)) {
            e.consume();
            return true;
        }
        return false;
    }

    /**
     * Checks if this Window is showing on screen.
     * @see java.awt.Component#setVisible(boolean)
    */
    public boolean isShowing() {
    return visible;
    }

    /**
     * Apply the settings in the given ResourceBundle to this Window.
     * Currently, this applies the ResourceBundle's ComponentOrientation
     * to this Window and all components contained within it.
     *
     * @see java.awt.ComponentOrientation
     * @since JDK1.2
     */
    public void applyResourceBundle(ResourceBundle rb) {
        // A package-visible utility on Container does all the work
        applyOrientation(ComponentOrientation.getOrientation(rb));
    }

    /**
     * Load the ResourceBundle with the given name using the default locale
     * and apply its settings to this window.
     * Currently, this applies the ResourceBundle's ComponentOrientation
     * to this Window and all components contained within it.
     *
     * @see java.awt.ComponentOrientation
     * @since JDK1.2
     */
    public void applyResourceBundle(String rbName) {
        applyResourceBundle(ResourceBundle.getBundle(rbName));
    }



   /*
    * Support for tracking all windows owned by this window
    */
    void addOwnedWindow(WeakReference weakWindow) {
        if (weakWindow != null) {
        if (ownedWindowList == null) {
            ownedWindowList = new Vector();
        }

        // this if statement should really be an assert, but we don't
        // have asserts...
        if (!ownedWindowList.contains(weakWindow)) {
            ownedWindowList.addElement(weakWindow);
        }
    }
    }

    void removeOwnedWindow(WeakReference weakWindow) {
        if (weakWindow != null && ownedWindowList != null) {
        ownedWindowList.removeElement(weakWindow);
    }
    }

    void connectOwnedWindow(Window child) {
        WeakReference weakChild = new WeakReference(child);
    child.weakThis = weakChild;
    child.parent = this;
    addOwnedWindow(weakChild);
    }

    /**
     * The window serialized data version.
     *
     * @serial
     */
    private int windowSerializedDataVersion = 1;

    /**
     * Writes default serializable fields to stream.  Writes
     * a list of serializable ItemListener(s) as optional data.
     * The non-serializable ItemListener(s) are detected and
     * no attempt is made to serialize them. Write a list of
     * child Windows as optional data.
     *
     * @serialData Null terminated sequence of 0 or more pairs.
     *             The pair consists of a String and Object.
     *             The String indicates the type of object and
     *             is one of the following :
     *             itemListenerK indicating an ItemListener object.
     * @serialData Null terminated sequence of 0 or more pairs.
     *             The pair consists of a String and Object.
     *             The String indicates the type of object and
     *             is one of the following :
     *             ownedWindowK indicating a child Window object.
     *
     * @see AWTEventMulticaster.save(ObjectOutputStream, String, EventListener)
     * @see java.awt.Component.itemListenerK
     * @see java.awt.Component.ownedWindowK
     */
    private void writeObject(ObjectOutputStream s)
      throws IOException
    {
      s.defaultWriteObject();

      AWTEventMulticaster.save(s, windowListenerK, windowListener);
      s.writeObject(null);

      if (ownedWindowList != null) {
      synchronized (ownedWindowList) {
          for (int i = 0; i < ownedWindowList.size(); i++) {
          Window child = (Window) (((WeakReference)
              (ownedWindowList.elementAt(i))).get());
          if (child != null) {
              s.writeObject(ownedWindowK);
              s.writeObject(child);
          }
          }
      }
      }
      s.writeObject(null);
    }

    /**
     * Read the default ObjectInputStream, a possibly null listener to
     * receive item events fired by the Window, and a possibly null
     * list of child Windows.
     * Unrecognised keys or values will be Ignored.
     *
     * @see removeActionListener()
     * @see addActionListener()
     */
    private void readObject(ObjectInputStream s)
      throws ClassNotFoundException, IOException
    {
      s.defaultReadObject();

      Object keyOrNull;
      while(null != (keyOrNull = s.readObject())) {
      String key = ((String)keyOrNull).intern();

      if (windowListenerK == key)
          addWindowListener((WindowListener)(s.readObject()));

      else // skip value for unrecognized key
          s.readObject();
      }

      try {
      while (null != (keyOrNull = s.readObject())) {
          String key = ((String)keyOrNull).intern();

          if (ownedWindowK == key)
          connectOwnedWindow((Window) s.readObject());

          else // skip value for unrecognized key
          s.readObject();
      }
      }
      catch (OptionalDataException e) {
      // 1.1 serialized form
      // ownedWindowList will be updated by Frame.readObject
      }

      setWarningString();
      this.inputContext = InputContext.getInstance();
    }

} // class Window


class FocusManager implements java.io.Serializable {
    Container focusRoot;
    Component focusOwner;

    /*
     * JDK 1.1 serialVersionUID
     */
    static final long serialVersionUID = 2491878825643557906L;

    FocusManager(Container cont) {
    focusRoot = cont;
    }

    /* Re-activate the last component with focus if it is still
     * visible and active.
     * If no component had focus yet, assign it to first component
     * capable of receiving it (visible, active, focusable).
     * If no visible, active, focusable components are present,
     * assign focus to the focus root.
     */
    void activateFocus() {
        boolean assigned = false;
        if (focusOwner != null) {
            if ((assigned = assignFocus(focusOwner, false)) != true) {
                assigned = focusNext(focusOwner);
            }
        } else {
            // assign to first component capable of taking it
            assigned = focusForward(focusRoot);
        }
        if (!assigned) {
            focusRoot.requestFocus();
        }
    }


    synchronized void setFocusOwner(Component c) {
        //System.out.println("FocusManager.setFocusOwner: "+c.name);
        focusOwner = c;
    }

    Component getFocusOwner() {
       return focusOwner;
    }

    boolean focusNext() {
       return focusNext(focusOwner);
    }

    boolean focusNext(Component base) {
        synchronized (focusRoot.getTreeLock()) { // BUGID4067845
            Component target = base;
            if (target != null && target.parent != null) {
                //System.out.println("FocusManager.focusNext: owner="+focusOwner);
                do {
                    boolean found = false;
                    Container p = target.parent;
                    Component c;
                    for (int i = 0; i < p.ncomponents; i++) {
                        c = p.component[i];
                        if (found) {
                            if (assignFocus(c)) {
                                return true;
                            }
                            if (c instanceof Container &&
                                    c.isVisible() &&
                                    c.isEnabled()) {
                                if (focusForward((Container)c)) {
                                    return true;
                                }
                            }
                        } else if (c == target) {
                            found = true;
                        }
                    }
                    target = p;
                } while (target != focusRoot && target.parent != null);
            }
            // wrap-around
            if (focusForward(focusRoot)) {
                return true;
            }

            return false;
        }
    }

    boolean focusPrevious() {
    return focusPrevious(focusOwner);
    }

    boolean focusPrevious(Component base) {
        synchronized (focusRoot.getTreeLock()) { // BUGID4067845
            Component target = base;
            if (target != null && target.parent != null) {
                do {
                    boolean found = false;
                    Container p = target.parent;
            if (p != null) {
            Component c;
            for (int i = p.ncomponents-1; i >= 0; i--) {
                c = p.component[i];
                if (found) {
                if (assignFocus(c)) {
                    return true;
                }
                if (c instanceof Container &&
                    c.isVisible() &&
                    c.isEnabled()) {
                    if (focusBackward((Container)c)) {
                    return true;
                    }
                }
                } else if (c == target) {
                found = true;
                }
            }
            }
                    target = p;
                } while (target != null && target != focusRoot);

            }
        // wrap-around
            if (focusBackward(focusRoot)) {
                return true;
            }
            return false;
        }
    }

    boolean assignFocus(Component c) {
        return assignFocus(c, true);
    }

    synchronized boolean assignFocus(Component c, boolean requireTraversable) {
        if (c.isVisible() && c.isEnabled() &&
            (!requireTraversable || c.isFocusTraversable())) {
            //System.out.println("FocusManager.assignFocus: "+c);
            c.requestFocus();
            return true;
        }
        return false;
    }

    synchronized boolean focusForward(Container cont) {
        for (int i = 0; i < cont.ncomponents; i++) {
            Component c = cont.component[i];
            if (assignFocus(c)) {
                return true;
            }
            if (c instanceof Container && c.isVisible() && c.isEnabled()) {
                if (focusForward((Container)c)) {
                    return true;
                }
            }
        }
        return false;
    }

    synchronized boolean focusBackward(Container cont) {
        for (int i = cont.ncomponents-1; i >= 0; i--) {
            Component c = cont.component[i];
            if (assignFocus(c)) {
                return true;
            }
            if (c instanceof Container && c.isVisible() && c.isEnabled()) {
                if (focusBackward((Container)c)) {
                    return true;
                }
            }
        }
        return false;
    }

}