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.dnd;
029
030import com.google.common.base.Optional;
031import com.google.gwt.dom.client.Element;
032
033/**
034 * Interface defining all methods used by drag and drop on a draggable element.<p>
035 *
036 * @since 8.0.0
037 */
038public interface I_CmsDraggable {
039
040    /**
041     * Gets an optional pair of integers which are to be used as an "offset delta" for the drag and drop process.<p>
042     *
043     * @return an optional array containing exactly 2 entries [x,y]
044     */
045    Optional<int[]> getCursorOffsetDelta();
046
047    /**
048     * Creates the drag helper element and attaches it into the DOM.<p>
049     *
050     * @param target the drop target
051     *
052     * @return the drag helper element
053     */
054    Element getDragHelper(I_CmsDropTarget target);
055
056    /**
057     * Returns the draggable element.<p>
058     *
059     * @return the element
060     */
061    Element getElement();
062
063    /**
064     * Returns the draggable id.<p>
065     *
066     * @return the id
067     */
068    String getId();
069
070    /**
071     * Returns the parent drop target or <code>null</code> if there is none.<p>
072     *
073     * @return the parent drop target
074     */
075    I_CmsDropTarget getParentTarget();
076
077    /**
078     * Creates the drag placeholder element.<p>
079     *
080     * @param target the drop target
081     *
082     * @return the drag placeholder element
083     */
084    Element getPlaceholder(I_CmsDropTarget target);
085
086    /**
087     * Executed on drag cancel.<p>
088     */
089    void onDragCancel();
090
091    /**
092     * Executed on drop.<p>
093     *
094     * @param target the drop target
095     */
096    void onDrop(I_CmsDropTarget target);
097
098    /**
099     * Executed on drag start.<p>
100     *
101     * @param target the current drop target
102     */
103    void onStartDrag(I_CmsDropTarget target);
104}