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.ui.input;
029
030import org.opencms.gwt.client.ui.CmsPushButton;
031import org.opencms.gwt.client.ui.I_CmsButton.ButtonStyle;
032import org.opencms.gwt.client.ui.css.I_CmsInputCss;
033import org.opencms.gwt.client.ui.css.I_CmsInputLayoutBundle;
034
035import com.google.gwt.event.dom.client.ClickEvent;
036import com.google.gwt.event.dom.client.ClickHandler;
037import com.google.gwt.event.logical.shared.HasValueChangeHandlers;
038import com.google.gwt.event.logical.shared.ValueChangeEvent;
039import com.google.gwt.event.logical.shared.ValueChangeHandler;
040import com.google.gwt.event.shared.HandlerRegistration;
041import com.google.gwt.user.client.ui.Composite;
042
043/**
044 * Tri-state checkbox.<p>
045 */
046public class CmsTriStateCheckBox extends Composite implements HasValueChangeHandlers<CmsTriStateCheckBox.State> {
047
048    /**
049     * The possible check box states.<p>
050     */
051    public enum State {
052        /** neither on nor off. */
053        middle, /** off. **/
054        off, /** on. **/
055        on;
056    }
057
058    /** The CSS bundle for this class. */
059    protected static final I_CmsInputCss CSS = I_CmsInputLayoutBundle.INSTANCE.inputCss();
060
061    /** The button which provides the actual widget layout. */
062    private CmsPushButton m_button;
063
064    /** The state to use as a next state if the user clicks on the checkbox while it is in its third state. */
065    private State m_nextStateAfterMiddle = State.off;
066
067    /** The current state. */
068    private State m_state;
069
070    /** The check box text. */
071    private String m_text;
072
073    /**
074     * Creates a new instance.<p>
075     *
076     * @param labelText the label text
077     */
078    public CmsTriStateCheckBox(String labelText) {
079
080        m_button = new CmsPushButton();
081        m_text = labelText;
082        initWidget(m_button);
083        m_button.setButtonStyle(ButtonStyle.TRANSPARENT, null);
084        addStyleName(CSS.triState());
085        m_state = State.middle;
086        updateStyle();
087        m_button.addClickHandler(new ClickHandler() {
088
089            public void onClick(ClickEvent event) {
090
091                CmsTriStateCheckBox.this.onClick();
092            }
093        });
094
095    }
096
097    /**
098     * @see com.google.gwt.event.logical.shared.HasValueChangeHandlers#addValueChangeHandler(com.google.gwt.event.logical.shared.ValueChangeHandler)
099     */
100    public HandlerRegistration addValueChangeHandler(ValueChangeHandler<State> handler) {
101
102        return addHandler(handler, ValueChangeEvent.getType());
103    }
104
105    /**
106     * Sets the state which the check box should transition to if the user clicks on it while it is neither on nor off.<p>
107     *
108     * @param state the target state
109     */
110    public void setNextStateAfterIntermediateState(State state) {
111
112        m_nextStateAfterMiddle = state;
113    }
114
115    /**
116     * Sets the state of the check box and optionally fires an event.<p>
117     *
118     * @param state the new state
119     * @param fireEvent true if a ValueChangeEvent should be fired
120     */
121    public void setState(State state, boolean fireEvent) {
122
123        boolean changed = m_state != state;
124        m_state = state;
125        if (changed) {
126            updateStyle();
127        }
128        if (fireEvent) {
129            ValueChangeEvent.fire(this, state);
130        }
131    }
132
133    /**
134     * Sets the check box label text.<p>
135     *
136     * @param text the new label text
137     */
138    public void setText(String text) {
139
140        m_text = text;
141        updateStyle();
142    }
143
144    /**
145     * Handles clicks on the check box.<p>
146     */
147    protected void onClick() {
148
149        State newState = getNextState(m_state);
150        setState(newState, true);
151    }
152
153    /**
154     * Gets the image class to use for the check box.<p>
155     *
156     * @return the image class
157     */
158    private String getImageClass() {
159
160        switch (m_state) {
161            case on:
162                return CSS.triStateOn();
163            case off:
164                return CSS.triStateOff();
165            case middle:
166            default:
167                return CSS.triStateMedium();
168        }
169
170    }
171
172    /**
173     * Gets the state which the check box would change to if cilcked on in a given state.<p>
174     *
175     * @param state the original state
176     * @return the next state
177     */
178    private State getNextState(State state) {
179
180        State nextState = null;
181        switch (state) {
182            case off:
183                nextState = State.on;
184                break;
185            case on:
186                nextState = State.off;
187                break;
188            case middle:
189            default:
190                nextState = m_nextStateAfterMiddle;
191        }
192        return nextState;
193    }
194
195    /**
196     * Updates the UI state according to the logical state.<p>
197     */
198    private void updateStyle() {
199
200        m_button.setUpFace(m_text, getImageClass());
201    }
202}