| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /* $Id$ */ |
| |
| package org.apache.fop.accessibility; |
| |
| import javax.xml.transform.Source; |
| import javax.xml.transform.Templates; |
| import javax.xml.transform.Transformer; |
| import javax.xml.transform.TransformerConfigurationException; |
| import javax.xml.transform.sax.SAXTransformerFactory; |
| import javax.xml.transform.sax.TransformerHandler; |
| import javax.xml.transform.stream.StreamSource; |
| |
| import org.xml.sax.helpers.DefaultHandler; |
| |
| import org.apache.fop.apps.FOPException; |
| import org.apache.fop.apps.FOUserAgent; |
| |
| /** |
| * Helper class for FOP's accessibility features. |
| */ |
| public final class Accessibility { |
| |
| /** Constant string for the rendering options key to enable accessibility features. */ |
| public static final String ACCESSIBILITY = "accessibility"; |
| |
| // TODO what if the default factory is not a SAXTransformerFactory? |
| private static SAXTransformerFactory tfactory |
| = (SAXTransformerFactory)SAXTransformerFactory.newInstance(); |
| |
| private static Templates addPtrTemplates; |
| |
| private static Templates reduceFOTreeTemplates; |
| |
| private Accessibility() { } |
| |
| /** |
| * Decorates the given handler so the structure tree used for accessibility |
| * features can be branched off the main content stream. |
| * @param handler the handler to decorate |
| * @param userAgent the user agent |
| * @return the decorated handler |
| * @throws FOPException if an error occurs setting up the decoration |
| */ |
| public static DefaultHandler decorateDefaultHandler(DefaultHandler handler, |
| FOUserAgent userAgent) throws FOPException { |
| try { |
| setupTemplates(); |
| TransformerHandler addPtr = tfactory.newTransformerHandler(addPtrTemplates); |
| Transformer reduceFOTree = reduceFOTreeTemplates.newTransformer(); |
| return new AccessibilityPreprocessor(addPtr, reduceFOTree, userAgent, handler); |
| } catch (TransformerConfigurationException e) { |
| throw new FOPException(e); |
| } |
| } |
| |
| private static synchronized void setupTemplates() throws TransformerConfigurationException { |
| if (addPtrTemplates == null) { |
| addPtrTemplates = loadTemplates("addPtr.xsl"); |
| } |
| if (reduceFOTreeTemplates == null) { |
| reduceFOTreeTemplates = loadTemplates("reduceFOTree.xsl"); |
| } |
| } |
| |
| private static Templates loadTemplates(String source) throws TransformerConfigurationException { |
| Source src = new StreamSource(Accessibility.class.getResource(source).toExternalForm()); |
| return tfactory.newTemplates(src); |
| } |
| |
| } |