content: /*
   * This library is part of OpenCms -
   * the Open Source Content Management System
   *
   * Copyright (c) Alkacon Software GmbH & Co. KG (https://www.alkacon.com)
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library 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
   * Lesser General Public License for more details.
   *
   * For further information about Alkacon Software, please see the
   * company website: https://www.alkacon.com
   *
   * For further information about OpenCms, please see the
   * project website: https://www.opencms.org
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  package org.opencms.ui.client;
  
  import org.opencms.ui.components.extensions.CmsScrollPositionCss;
  import org.opencms.ui.shared.components.CmsScrollPositionCssState;
  
  import com.google.gwt.event.dom.client.ScrollEvent;
  import com.google.gwt.event.dom.client.ScrollHandler;
  import com.google.gwt.user.client.ui.Widget;
  import com.vaadin.client.ComponentConnector;
  import com.vaadin.client.ServerConnector;
  import com.vaadin.client.extensions.AbstractExtensionConnector;
  import com.vaadin.shared.ui.Connect;
  
  /**
   * This connector will manipulate the CSS classes of the extended widget depending on the scroll position.<p>
   */
  @Connect(CmsScrollPositionCss.class)
  public class CmsScrollPositionCssConnector extends AbstractExtensionConnector {
  
      /** The serial version id. */
      private static final long serialVersionUID = -9079215265941920364L;
  
      /** The widget to enhance. */
      private Widget m_widget;
  
      /**
       * @see com.vaadin.client.ui.AbstractConnector#getState()
       */
      @Override
      public CmsScrollPositionCssState getState() {
  
          return (CmsScrollPositionCssState)super.getState();
      }
  
      /**
       * @see com.vaadin.client.extensions.AbstractExtensionConnector#extend(com.vaadin.client.ServerConnector)
       */
      @Override
      protected void extend(ServerConnector target) {
  
          // Get the extended widget
          m_widget = ((ComponentConnector)target).getWidget();
          m_widget.addDomHandler(new ScrollHandler() {
  
              public void onScroll(ScrollEvent event) {
  
                  handleScroll(event);
  
              }
          }, ScrollEvent.getType());
      }
  
      /**
       * Handles the scroll event.<p>
       *
       * @param event the scroll event
       */
      protected void handleScroll(ScrollEvent event) {
  
          String styleName = getState().getStyleName();
          int scrollBarrier = getState().getScrollBarrier();
          int barrierMargin = getState().getBarrierMargin();
          if ((m_widget != null) && (scrollBarrier > 0) && (styleName != null)) {
              if (m_widget.getElement().getScrollTop() > (scrollBarrier + barrierMargin)) {
                  m_widget.addStyleDependentName(styleName);
                  m_widget.addStyleName(styleName);
              } else if (m_widget.getElement().getScrollTop() < (scrollBarrier - barrierMargin)) {
                  m_widget.removeStyleDependentName(styleName);
                  m_widget.removeStyleName(styleName);
              }
          }
      }
  }
  