001// Licensed under the Apache License, Version 2.0 (the "License"); 002// you may not use this file except in compliance with the License. 003// You may obtain a copy of the License at 004// 005// http://www.apache.org/licenses/LICENSE-2.0 006// 007// Unless required by applicable law or agreed to in writing, software 008// distributed under the License is distributed on an "AS IS" BASIS, 009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 010// See the License for the specific language governing permissions and 011// limitations under the License. 012 013package org.apache.tapestry5.services.assets; 014 015import org.apache.tapestry5.commons.Resource; 016import org.apache.tapestry5.http.ContentType; 017 018import java.io.IOException; 019import java.io.InputStream; 020 021/** 022 * A transformer is used to read a {@link Resource} and pass it through a transformation stage, to get a 023 * stream that can be used on the client side. Examples of this are languages that "compile" to 024 * JavaScript, or any of a few higher-level versions of CSS that are compiled to standard CSS. 025 * ResourceTransformers are contributed to the {@link StreamableResourceSource} service. 026 * 027 * @since 5.3 028 * @see StreamableResourceSource 029 */ 030public interface ResourceTransformer 031{ 032 /** 033 * Returns the MIME type of a transformed stream. 034 * 035 * @since 5.4 036 */ 037 ContentType getTransformedContentType(); 038 039 /** 040 * Read the source input stream and provide a new input stream of the transformed content. 041 * 042 * @param source 043 * input content 044 * @param dependencies 045 * allows additional dependencies of the source to be tracked 046 * @return stream of output content 047 * @throws IOException 048 */ 049 InputStream transform(Resource source, ResourceDependencies dependencies) throws IOException; 050}