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.tapestry.IMarkupWriter;
018    import org.apache.tapestry.IRequestCycle;
019    
020    /**
021     * Implements a component that manages an HTML &lt;button&gt; form element. [ <a
022     * href="../../../../../ComponentReference/Button.html">Component Reference </a>]
023     * <p>
024     * This component is useful for attaching JavaScript onclick event handlers.
025     * 
026     * @author Howard Lewis Ship
027     * @author Paul Geerts
028     * @author Malcolm Edgar
029     * @author Paul Ferraro
030     */
031    public abstract class Button extends AbstractFormComponent
032    {
033        /**
034         * @see org.apache.tapestry.form.AbstractFormComponent#renderFormComponent(org.apache.tapestry.IMarkupWriter,
035         *      org.apache.tapestry.IRequestCycle)
036         */
037        protected void renderFormComponent(IMarkupWriter writer, IRequestCycle cycle)
038        {
039            writer.begin("button");
040            writer.attribute("type", "button");
041            writer.attribute("name", getName());
042    
043            if (isDisabled())
044            {
045                writer.attribute("disabled", "disabled");
046            }
047    
048            renderIdAttribute(writer, cycle);
049    
050            renderInformalParameters(writer, cycle);
051    
052            String label = getLabel();
053    
054            if (label != null)
055                writer.print(label);
056            else
057                renderBody(writer, cycle);
058    
059            writer.end();
060        }
061    
062        /**
063         * @see org.apache.tapestry.form.AbstractFormComponent#rewindFormComponent(org.apache.tapestry.IMarkupWriter, org.apache.tapestry.IRequestCycle)
064         */
065        protected void rewindFormComponent(IMarkupWriter writer, IRequestCycle cycle)
066        {
067            // Do nothing
068        }
069        
070        /**
071         * @see org.apache.tapestry.form.IFormComponent#getDisplayName()
072         */
073        public String getDisplayName()
074        {
075            return null;
076        }
077    
078        /**
079         * @see org.apache.tapestry.form.IFormComponent#isDisabled()
080         */
081        public boolean isDisabled()
082        {
083            return false;
084        }
085    
086        public abstract String getLabel();
087    }