001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.form;
016    
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.tapestry.AbstractComponent;
019    import org.apache.tapestry.IMarkupWriter;
020    import org.apache.tapestry.IRequestCycle;
021    import org.apache.tapestry.Tapestry;
022    
023    /**
024     * A component that renders an HTML <option> form element. Such a component must be wrapped
025     * (possibly indirectly) inside a {@link Select}component. [ <a
026     * href="../../../../../ComponentReference/Option.html">Component Reference </a>]
027     * 
028     * @author Howard Lewis Ship
029     */
030    
031    public abstract class Option extends AbstractComponent
032    {
033        /**
034         * Renders the &lt;option&gt; element, or responds when the form containing the element is
035         * submitted (by checking {@link Form#isRewinding()}.
036         * <p>
037         * If the <code>label</code> property is set, it is inserted inside the &lt;option&gt;
038         * element.
039         */
040    
041        protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
042        {
043            Select select = Select.get(cycle);
044            if (select == null)
045                throw new ApplicationRuntimeException(Tapestry
046                        .getMessage("Option.must-be-contained-by-select"), this, null, null);
047    
048            // It isn't enough to know whether the cycle in general is rewinding, need to know
049            // specifically if the form which contains this component is rewinding.
050    
051            boolean rewinding = select.isRewinding();
052    
053            String value = select.getNextOptionId();
054    
055            if (rewinding)
056            {
057                if (!select.isDisabled())
058                    setSelected(select.isSelected(value));
059    
060                renderBody(writer, cycle);
061            }
062            else
063            {
064                writer.begin("option");
065    
066                writer.attribute("value", value);
067    
068                if (isSelected())
069                    writer.attribute("selected", "selected");
070    
071                renderInformalParameters(writer, cycle);
072    
073                String label = getLabel();
074    
075                if (label != null)
076                    writer.print(label);
077    
078                renderBody(writer, cycle);
079    
080                writer.end();
081            }
082    
083        }
084    
085        public abstract String getLabel();
086    
087        public abstract boolean isSelected();
088    
089        public abstract void setSelected(boolean selected);
090    }