source: trunk/gli/src/org/greenstone/gatherer/gui/ModalDialog.java@ 8480

/*#########################################################################
 *
 * 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 java.awt.event.*;
import javax.swing.*;
import org.greenstone.gatherer.DebugStream;


/** 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. */
// feedback note: veronika had changed all the super constructor calls to 
// use modal instead of false - not sure if this is needed so I have not 
// put that in. --kjdon
public class ModalDialog
    extends JDialog {

    /** The current modal dialog being shown on screen, if any. */
    static public ModalDialog current_modal = null;

    /** 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);
    }

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

    /** 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;
    }
    
    /** 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;
    }

    /** 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;
    }

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

    /** Constructor.
     * @param parent the Frame which is the owener of this dialog.
     * @param modal whether this dialog is modal or not
     */
    public ModalDialog(Frame parent, boolean modal) {
    super(parent, "", false);
    this.modal = modal;
    }
    
    /** 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);
    }

    /** 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;
    }

    public void dispose() {
    super.dispose();
    }

    /** Ensures the current dialog is visible. */
    public void makeVisible() {
    super.setVisible(true);
    }

    /** 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)
    {
    if (visible) {
        current_modal = this;
    }
    else {
        current_modal = null;
    }

    // If we are in the AWT Dispatch thread then it is all good.
    if (SwingUtilities.isEventDispatchThread()) {
        super.setVisible(visible);
        if (modal && visible) {
        EventQueue theQueue = getToolkit().getSystemEventQueue();
        while (isVisible()) {
            try {
            AWTEvent event = theQueue.getNextEvent();
            Object src = event.getSource();

            // Block all keyboard and mouse events to the parent component
            if (src.equals(getParent())) {
                if (event instanceof KeyEvent || event instanceof MouseEvent) {
                // System.err.println("Event to parent component blocked.");
                continue;
                }
            }

            // Re-dispatch other events
            if (event instanceof ActiveEvent) {
                ((ActiveEvent) event).dispatch();
            }               
            else if (src instanceof Component) {
                ((Component) src).dispatchEvent(event);
            }
            }
            catch (Exception exception) {
            DebugStream.printStackTrace(exception);
            }
        }
        }
    }
    else {
        try {
        SwingUtilities.invokeAndWait(new MakeDialogVisibleTask(this, visible));
        }
        catch (Exception exception) {
        DebugStream.printStackTrace(exception);
        }
    }
    }
    
    private class MakeDialogVisibleTask
    implements Runnable {
    private boolean make_visible;
    private ModalDialog dialog;
    public MakeDialogVisibleTask(ModalDialog dialog, boolean make_visible) {
        this.dialog = dialog;
        this.make_visible = make_visible;
    }
    public void run() {
        // Blocks until the user dismisses the dialog
        dialog.setVisible(make_visible);
    }
    }

    /** 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;
    }
}