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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.

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/*
 * Copyright (C) 2006-2010 Schlichtherle IT Services
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.schlichtherle.swing.event;

import de.schlichtherle.swing.EnhancedPanel;

import java.awt.AWTEvent;
import java.awt.Window;

/**
 * Fired when the ancestor window of an {@link EnhancedPanel} is shown or
 * hidden.
 * 
 * Note that since TrueZIP 6.1, this class has been refactored to subclass
 * {@link AWTEvent} (which subclasses {@link java.util.EventObject}) instead
 * of {@code EventObject} directly.
 * This has been done in order to allow coalescing multiple events for the
 * same cause by posting them to the AWT's Event Queue, from which the
 * coalesced event would then be dispatched by AWT's Event Dispatching Thread.
 * 
 * However, since TrueZIP 6.4, these events are fired synchronously
 * again, whereby it is ensured that only a single event is fired for each
 * cause. The super class is kept for backwards compatibility only.
 *
 * @author Christian Schlichtherle
 * @version $Id$
 * @since TrueZIP 5.1
 */
public class PanelEvent extends AWTEvent {

    private static final long serialVersionUID = -7614118389065035365L;

    /** The id for Ancestor Window Shown Event. */
    public static final int ANCESTOR_WINDOW_SHOWN  = RESERVED_ID_MAX + 1;

    /** The id for Ancestor Window Hidden Event. */
    public static final int ANCESTOR_WINDOW_HIDDEN = RESERVED_ID_MAX + 2;

    /**
     */
    public PanelEvent(EnhancedPanel source, int id) {
        super(source, id);

        switch (id) {
            case ANCESTOR_WINDOW_SHOWN:
            case ANCESTOR_WINDOW_HIDDEN:
                break;

            default:
                throw new IllegalArgumentException();
        }
    }

    /**
     * Returns the source of this event as an {@code EnhancedPanel}
     * or {@code null} if it's not an instance of this class.
     */
    public EnhancedPanel getSourcePanel() {
        return source instanceof EnhancedPanel ? (EnhancedPanel) source : null;
    }

    /**
     * Returns the ancestor window for this event or {@code null} if the
     * source of this event is not an {@code EnhancedPanel}.
     */
    public Window getAncestorWindow() {
        EnhancedPanel panel = getSourcePanel();
        return panel != null ? panel.getAncestorWindow() : null;
    }

    public String paramString() {
        switch (id) {
            case ANCESTOR_WINDOW_SHOWN:
                return "id=ANCESTOR_WINDOW_SHOWN";

            case ANCESTOR_WINDOW_HIDDEN:
                return "id=ANCESTOR_WINDOW_HIDDEN";

            default:
                throw new AssertionError();
        }
    }
}