001/*
002 * This library is part of OpenCms -
003 * the Open Source Content Management System
004 *
005 * Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
006 *
007 * This library is free software; you can redistribute it and/or
008 * modify it under the terms of the GNU Lesser General Public
009 * License as published by the Free Software Foundation; either
010 * version 2.1 of the License, or (at your option) any later version.
011 *
012 * This library is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 * Lesser General Public License for more details.
016 *
017 * For further information about Alkacon Software, please see the
018 * company website: http://www.alkacon.com
019 *
020 * For further information about OpenCms, please see the
021 * project website: http://www.opencms.org
022 *
023 * You should have received a copy of the GNU Lesser General Public
024 * License along with this library; if not, write to the Free Software
025 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
026 */
027
028package org.opencms.gwt.client.ui.tree;
029
030import com.google.gwt.event.logical.shared.OpenEvent;
031import com.google.gwt.user.client.Timer;
032
033/**
034 * Lazy list tree open handler abstract implementation.<p>
035 *
036 * @param <I> the specific lazy tree item implementation
037 *
038 * @since 8.0.0
039 *
040 * @see org.opencms.gwt.client.ui.tree.CmsLazyTree
041 * @see org.opencms.gwt.client.ui.tree.CmsLazyTreeItem
042 * @see org.opencms.gwt.client.ui.tree.I_CmsLazyOpenHandler
043 */
044public abstract class A_CmsLazyOpenHandler<I extends CmsLazyTreeItem> implements I_CmsLazyOpenHandler<I> {
045
046    /**
047     * Timer for showing the loading message.<p>
048     */
049    private final class OpenTimer extends Timer {
050
051        /** The tree item to open. */
052        private I m_target;
053
054        /**
055         * Default constructor.<p>
056         *
057         * @param target the tree item to open
058         */
059        public OpenTimer(I target) {
060
061            m_target = target;
062        }
063
064        /**
065         * @see com.google.gwt.user.client.Timer#run()
066         */
067        @Override
068        public void run() {
069
070            m_target.setOpen(true, false);
071            onFinishOpen(m_target);
072        }
073
074    }
075
076    /**
077     * Called when the opening process has finished and the children (if any) are visible.
078     *
079     * @param target the target tree item
080     */
081    public void onFinishOpen(I target) {
082
083        // do nothing
084
085    }
086
087    /**
088     * @see org.opencms.gwt.client.ui.tree.I_CmsLazyOpenHandler#onOpen(com.google.gwt.event.logical.shared.OpenEvent)
089     */
090    public void onOpen(OpenEvent<I> event) {
091
092        I target = event.getTarget();
093        if (target.getLoadState() != CmsLazyTreeItem.LoadState.UNLOADED) {
094            return;
095        }
096        final OpenTimer timer = new OpenTimer(target);
097        timer.schedule(500);
098        target.onStartLoading();
099        target.setOpen(false, false);
100        load(target, () -> {
101            timer.cancel();
102            timer.run();
103        });
104    }
105}