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.gwt.client.ui.tree;
  
  import com.google.gwt.event.logical.shared.OpenEvent;
  import com.google.gwt.user.client.Timer;
  
  /**
   * Lazy list tree open handler abstract implementation.<p>
   *
   * @param <I> the specific lazy tree item implementation
   *
   * @since 8.0.0
   *
   * @see org.opencms.gwt.client.ui.tree.CmsLazyTree
   * @see org.opencms.gwt.client.ui.tree.CmsLazyTreeItem
   * @see org.opencms.gwt.client.ui.tree.I_CmsLazyOpenHandler
   */
  public abstract class A_CmsLazyOpenHandler<I extends CmsLazyTreeItem> implements I_CmsLazyOpenHandler<I> {
  
      /**
       * Timer for showing the loading message.<p>
       */
      private final class OpenTimer extends Timer {
  
          /** The tree item to open. */
          private I m_target;
  
          /**
           * Default constructor.<p>
           *
           * @param target the tree item to open
           */
          public OpenTimer(I target) {
  
              m_target = target;
          }
  
          /**
           * @see com.google.gwt.user.client.Timer#run()
           */
          @Override
          public void run() {
  
              m_target.setOpen(true, false);
              onFinishOpen(m_target);
          }
  
      }
  
      /**
       * Called when the opening process has finished and the children (if any) are visible.
       *
       * @param target the target tree item
       */
      public void onFinishOpen(I target) {
  
          // do nothing
  
      }
  
      /**
       * @see org.opencms.gwt.client.ui.tree.I_CmsLazyOpenHandler#onOpen(com.google.gwt.event.logical.shared.OpenEvent)
       */
      public void onOpen(OpenEvent<I> event) {
  
          I target = event.getTarget();
          if (target.getLoadState() != CmsLazyTreeItem.LoadState.UNLOADED) {
              return;
          }
          final OpenTimer timer = new OpenTimer(target);
          timer.schedule(500);
          target.onStartLoading();
          target.setOpen(false, false);
          load(target, () -> {
              timer.cancel();
              timer.run();
          });
      }
  }
  