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
015package org.apache.tapestry.form;
016
017import org.apache.hivemind.ApplicationRuntimeException;
018import org.apache.tapestry.AbstractComponent;
019import org.apache.tapestry.IMarkupWriter;
020import org.apache.tapestry.IRequestCycle;
021import 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
031public 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}