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.ui.client;
029
030import org.opencms.ui.components.extensions.CmsScrollPositionCss;
031import org.opencms.ui.shared.components.CmsScrollPositionCssState;
032
033import com.google.gwt.event.dom.client.ScrollEvent;
034import com.google.gwt.event.dom.client.ScrollHandler;
035import com.google.gwt.user.client.ui.Widget;
036import com.vaadin.client.ComponentConnector;
037import com.vaadin.client.ServerConnector;
038import com.vaadin.client.extensions.AbstractExtensionConnector;
039import com.vaadin.shared.ui.Connect;
040
041/**
042 * This connector will manipulate the CSS classes of the extended widget depending on the scroll position.<p>
043 */
044@Connect(CmsScrollPositionCss.class)
045public class CmsScrollPositionCssConnector extends AbstractExtensionConnector {
046
047    /** The serial version id. */
048    private static final long serialVersionUID = -9079215265941920364L;
049
050    /** The widget to enhance. */
051    private Widget m_widget;
052
053    /**
054     * @see com.vaadin.client.ui.AbstractConnector#getState()
055     */
056    @Override
057    public CmsScrollPositionCssState getState() {
058
059        return (CmsScrollPositionCssState)super.getState();
060    }
061
062    /**
063     * @see com.vaadin.client.extensions.AbstractExtensionConnector#extend(com.vaadin.client.ServerConnector)
064     */
065    @Override
066    protected void extend(ServerConnector target) {
067
068        // Get the extended widget
069        m_widget = ((ComponentConnector)target).getWidget();
070        m_widget.addDomHandler(new ScrollHandler() {
071
072            public void onScroll(ScrollEvent event) {
073
074                handleScroll(event);
075
076            }
077        }, ScrollEvent.getType());
078    }
079
080    /**
081     * Handles the scroll event.<p>
082     *
083     * @param event the scroll event
084     */
085    protected void handleScroll(ScrollEvent event) {
086
087        String styleName = getState().getStyleName();
088        int scrollBarrier = getState().getScrollBarrier();
089        int barrierMargin = getState().getBarrierMargin();
090        if ((m_widget != null) && (scrollBarrier > 0) && (styleName != null)) {
091            if (m_widget.getElement().getScrollTop() > (scrollBarrier + barrierMargin)) {
092                m_widget.addStyleDependentName(styleName);
093                m_widget.addStyleName(styleName);
094            } else if (m_widget.getElement().getScrollTop() < (scrollBarrier - barrierMargin)) {
095                m_widget.removeStyleDependentName(styleName);
096                m_widget.removeStyleName(styleName);
097            }
098        }
099    }
100}