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
015package org.apache.tapestry5.corelib.components;
016
017import org.apache.tapestry5.BindingConstants;
018import org.apache.tapestry5.ComponentResources;
019import org.apache.tapestry5.MarkupWriter;
020import org.apache.tapestry5.annotations.Parameter;
021import org.apache.tapestry5.ioc.annotations.Inject;
022import 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 */
031public 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}