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.input;
  
  import org.opencms.gwt.client.ui.CmsPushButton;
  import org.opencms.gwt.client.ui.I_CmsButton.ButtonStyle;
  import org.opencms.gwt.client.ui.css.I_CmsInputCss;
  import org.opencms.gwt.client.ui.css.I_CmsInputLayoutBundle;
  
  import com.google.gwt.event.dom.client.ClickEvent;
  import com.google.gwt.event.dom.client.ClickHandler;
  import com.google.gwt.event.logical.shared.HasValueChangeHandlers;
  import com.google.gwt.event.logical.shared.ValueChangeEvent;
  import com.google.gwt.event.logical.shared.ValueChangeHandler;
  import com.google.gwt.event.shared.HandlerRegistration;
  import com.google.gwt.user.client.ui.Composite;
  
  /**
   * Tri-state checkbox.<p>
   */
  public class CmsTriStateCheckBox extends Composite implements HasValueChangeHandlers<CmsTriStateCheckBox.State> {
  
      /**
       * The possible check box states.<p>
       */
      public enum State {
          /** neither on nor off. */
          middle, /** off. **/
          off, /** on. **/
          on;
      }
  
      /** The CSS bundle for this class. */
      protected static final I_CmsInputCss CSS = I_CmsInputLayoutBundle.INSTANCE.inputCss();
  
      /** The button which provides the actual widget layout. */
      private CmsPushButton m_button;
  
      /** The state to use as a next state if the user clicks on the checkbox while it is in its third state. */
      private State m_nextStateAfterMiddle = State.off;
  
      /** The current state. */
      private State m_state;
  
      /** The check box text. */
      private String m_text;
  
      /**
       * Creates a new instance.<p>
       *
       * @param labelText the label text
       */
      public CmsTriStateCheckBox(String labelText) {
  
          m_button = new CmsPushButton();
          m_text = labelText;
          initWidget(m_button);
          m_button.setButtonStyle(ButtonStyle.TRANSPARENT, null);
          addStyleName(CSS.triState());
          m_state = State.middle;
          updateStyle();
          m_button.addClickHandler(new ClickHandler() {
  
              public void onClick(ClickEvent event) {
  
                  CmsTriStateCheckBox.this.onClick();
              }
          });
  
      }
  
      /**
       * @see com.google.gwt.event.logical.shared.HasValueChangeHandlers#addValueChangeHandler(com.google.gwt.event.logical.shared.ValueChangeHandler)
       */
      public HandlerRegistration addValueChangeHandler(ValueChangeHandler<State> handler) {
  
          return addHandler(handler, ValueChangeEvent.getType());
      }
  
      /**
       * Sets the state which the check box should transition to if the user clicks on it while it is neither on nor off.<p>
       *
       * @param state the target state
       */
      public void setNextStateAfterIntermediateState(State state) {
  
          m_nextStateAfterMiddle = state;
      }
  
      /**
       * Sets the state of the check box and optionally fires an event.<p>
       *
       * @param state the new state
       * @param fireEvent true if a ValueChangeEvent should be fired
       */
      public void setState(State state, boolean fireEvent) {
  
          boolean changed = m_state != state;
          m_state = state;
          if (changed) {
              updateStyle();
          }
          if (fireEvent) {
              ValueChangeEvent.fire(this, state);
          }
      }
  
      /**
       * Sets the check box label text.<p>
       *
       * @param text the new label text
       */
      public void setText(String text) {
  
          m_text = text;
          updateStyle();
      }
  
      /**
       * Handles clicks on the check box.<p>
       */
      protected void onClick() {
  
          State newState = getNextState(m_state);
          setState(newState, true);
      }
  
      /**
       * Gets the image class to use for the check box.<p>
       *
       * @return the image class
       */
      private String getImageClass() {
  
          switch (m_state) {
              case on:
                  return CSS.triStateOn();
              case off:
                  return CSS.triStateOff();
              case middle:
              default:
                  return CSS.triStateMedium();
          }
  
      }
  
      /**
       * Gets the state which the check box would change to if cilcked on in a given state.<p>
       *
       * @param state the original state
       * @return the next state
       */
      private State getNextState(State state) {
  
          State nextState = null;
          switch (state) {
              case off:
                  nextState = State.on;
                  break;
              case on:
                  nextState = State.off;
                  break;
              case middle:
              default:
                  nextState = m_nextStateAfterMiddle;
          }
          return nextState;
      }
  
      /**
       * Updates the UI state according to the logical state.<p>
       */
      private void updateStyle() {
  
          m_button.setUpFace(m_text, getImageClass());
      }
  }
  