001    // Copyright 2009, 2010, 2011 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.tapestry5.corelib.components;
016    
017    import org.apache.tapestry5.BindingConstants;
018    import org.apache.tapestry5.ComponentResources;
019    import org.apache.tapestry5.MarkupWriter;
020    import org.apache.tapestry5.annotations.Parameter;
021    import org.apache.tapestry5.ioc.annotations.Inject;
022    import org.apache.tapestry5.services.javascript.JavaScriptSupport;
023    
024    /**
025     * Triggers an arbitrary event during rendering. This is often useful to add JavaScript
026     * to a page or a component (via calls to the {@link JavaScriptSupport} environmental).
027     * 
028     * @since 5.2.0
029     * @tapestrydoc
030     */
031    public class Trigger
032    {
033        @Parameter(defaultPrefix = BindingConstants.LITERAL)
034        private String event;
035    
036        @Inject
037        private ComponentResources resources;
038    
039        String defaultEvent()
040        {
041            return this.resources.getId();
042        }
043    
044        boolean beginRender(MarkupWriter writer)
045        {
046            this.resources.triggerEvent(this.event, new Object[]
047            { writer }, null);
048            return false;
049        }
050    
051    }