source: trunk/gli/src/org/greenstone/gatherer/gui/ModalDialog.java@ 6539

/*
 * ModalDialog
 * 
 * GLI 2.3c
 *
 * 30May2003 
 *
 *#########################################################################
 *
 * A component of the Gatherer application, part of the Greenstone digital
 * library suite from the New Zealand Digital Library Project at the
 * University of Waikato, New Zealand.
 *
 * Author: John Thompson, Greenstone Digital Library, University of Waikato
 *
 * Copyright (C) 1999 New Zealand Digital Library Project
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *########################################################################
 */
package org.greenstone.gatherer.gui;

import java.awt.*;
import javax.swing.*;
import org.greenstone.gatherer.Gatherer;
/** An extension of the JDialog that overrides the JVM's typical modal behaviour. This typical behaviour is that when a modal dialog is opened, all other windows cease to respond to user events until the modal dialog is disposed. However this prevents us opening the help documents property whenever a modal dialog is open. Thus we override the modal behaviour so that only the owner frame or dialog is blocked. 
 * Note that because we always call the super constructor with modal set to false, this should be made visible with setVisible(true) rather than show() which will return straight away. */
public class ModalDialog
    extends JDialog {
    /** true if this dialog should be modal, ie block user actions to its owner window, false otherwise. */
    protected boolean modal = false;
    /** true if this dialog is currently waiting some thread. */
    protected boolean waiting = false;

    /** Constructor.
     */
    public ModalDialog() {
    super((Frame)null, "", false);
    Gatherer.current_modal = this;
    }

    /** Constructor.
     * @param parent the Dialog which is the owener of this dialog.
    */
    public ModalDialog(Dialog parent) {
    super(parent, "", false);
    Gatherer.current_modal = this;
    }

    /** Constructor.
     * @param parent the Dialog which is the owener of this dialog.
     * @param modal true if this dialog should be modal, ie block user actions to its owner window, false otherwise.
     */
    public ModalDialog(Dialog parent, boolean modal) {
    super(parent, "", false);
    this.modal = modal;
    Gatherer.current_modal = this;
    }
    
    /** Constructor.
     * @param parent the Dialog which is the owner of this dialog.
     * @param title the String to use as the title for this dialog.
     */
    public ModalDialog(Dialog parent, String title) {
    super (parent, title, false);
    this.modal = false;
    Gatherer.current_modal = this;
    }

    /** Constructor.
     * @param parent the Dialog which is the owener of this dialog.
     * @param title the String to use as the title for this dialog.
     * @param modal true if this dialog should be modal, ie block user actions to its owner window, false otherwise.
     */
    public ModalDialog(Dialog parent, String title, boolean modal) {
    super (parent, title, false);
    this.modal = modal;
    Gatherer.current_modal = this;
    }

   /** Constructor.
     * @param parent the Frame which is the owener of this dialog.
     */
    public ModalDialog(Frame parent) {
    super(parent, "", false);
    Gatherer.current_modal = this;
    }

    /** Constructor.
     * @param parent the Frame which is the owener of this dialog.
     * @param title the String to use as the title for this dialog.
     */
    public ModalDialog(Frame parent, boolean modal) {
    super(parent, "", false);
    this.modal = modal;
    Gatherer.current_modal = this;
    }
    
    /** Constructor.
     * @param parent the Frame which is the owner of this dialog.
     * @param title the String to use as the title for this dialog.
     */
    public ModalDialog(Frame parent, String title) {
    super (parent, title, false);
    Gatherer.current_modal = this;
    }

    /** Constructor.
     * @param parent the Frame which is the owener of this dialog.
     * @param title the String to use as the title for this dialog.
     * @param modal true if this dialog should be modal, ie block user actions to its owner window, false otherwise.
     */
    public ModalDialog(Frame parent, String title, boolean modal) {
    super (parent, title, false);
    this.modal = modal;
    Gatherer.current_modal = this;
    }

    public void dispose() {
    Gatherer.current_modal = null;
    super.dispose();
    }

    /** The set visible method is overriden to provide modal functionality. It essentially hijacks control of the event dispatch thread while the dialog is open, only allowing non-user events to be passed to the parent dialog. Furthermore it only has this effect within the current AWT component tree by utilitizing the TreeLock.
     * @param visible true if this dialog should be painted on-screen, false otherwise.
     */
    public void setVisible (boolean visible) {
    ///ystem.err.println("setVisible(" + visible + ")");
    getParent ().setEnabled (!(visible && modal));
    super.setVisible (visible);
    if (modal && visible) {
        try {
        if (SwingUtilities.isEventDispatchThread ()) {
            ///ystem.err.println("is Event Dispatch Thread. Only process certain events.");
            EventQueue theQueue = getToolkit().getSystemEventQueue();
            while (isVisible ()) {
            AWTEvent event = theQueue.getNextEvent();
            Object src = event.getSource ();
            if (event instanceof ActiveEvent) {
                ///ystem.err.println("ActiveEvent:");
                ((ActiveEvent) event).dispatch ();
            } else if (src instanceof Component) {
                ///ystem.err.println("Source is component");
                ((Component) src).dispatchEvent (event);
            }
            else {
                ///ystem.err.println("Event blocked");
            }
            }
            ///ystem.err.println("No longer visible - AWT");
                } else synchronized (getTreeLock ()) {
            ///ystem.err.println("is other Thread. Block all events.");
            while (isVisible ()) {
            try {
                waiting = true;
                getTreeLock().wait();
                waiting = false;
            } catch (InterruptedException e) {
                ///ystem.err.println("Interrupted!!!");
                break;
            }
            }
            ///ystem.err.println("No longer visible - Other");
        }
            } catch (Exception ex) { 
        ex.printStackTrace(); 
        }
    }
    else if(modal && !visible && waiting) {
        ///ystem.err.println("Hiding dialog. Tree lock is: " + getTreeLock());
        synchronized(getTreeLock()) {
        ///ystem.err.println("Notify!");
        getTreeLock().notify();
        }
    }
    else if(modal && !waiting) {
        ///ystem.err.println("Modal Dialog is not currently waiting.");
    }
    else if(!modal) {
        ///ystem.err.println("Dialog is not modal.");
    }
    }
    
    /** Overridden method so we can control modality and not rely on the Dialog default.
     * @param modal true if this dialog should be modal, ie block user actions to its owner window, false otherwise.
     */
    public void setModal (boolean modal) {
    this.modal = modal;
    }
}