001// Copyright 2011, 2012 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.services.assets; 016 017import org.apache.tapestry5.ioc.Resource; 018 019import java.io.IOException; 020import java.io.InputStream; 021 022/** 023 * A transformer is used to read a {@link Resource} and pass it through a transformation stage, to get a 024 * stream that can be used on the client side. Examples of this are languages that "compile" to 025 * JavaScript, or any of a few higher-level versions of CSS that are compiled to standard CSS. 026 * ResourceTransformers are contributed to the {@link StreamableResourceSource} service. 027 * 028 * @since 5.3 029 * @see StreamableResourceSource 030 */ 031public interface ResourceTransformer 032{ 033 /** 034 * Returns the MIME type of a transformed stream. 035 * 036 * @since 5.4 037 */ 038 String getTransformedContentType(); 039 040 /** 041 * Read the source input stream and provide a new input stream of the transformed content. 042 * 043 * @param source 044 * input content 045 * @param dependencies 046 * allows additional dependencies of the source to be tracked 047 * @return stream of output content 048 * @throws IOException 049 */ 050 InputStream transform(Resource source, ResourceDependencies dependencies) throws IOException; 051}