package org.apache.turbine.modules.screens;

 /*

  * 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.

  */

 // Turbine stuff.

 import org.apache.turbine.modules.Screen;

 import org.apache.turbine.pipeline.PipelineData;

 import org.apache.turbine.util.RunData;

 /**

  * Base class for writing Screens that output binary data.  This class

  * is provided as a helper class for those who want to write Screens

  * that output raw binary data.  For example, it may be extended into

  * a Screen that outputs a SVG file or a SWF (Flash Player format)

  * movie.  The only thing one has to do is to implement the two

  * methods <code>getContentType(PipelineData data)</code> and

  * <code>doOutput(PipelineData data)</code> (see below).

  *

  * <p> You might want to take a look at the ImageServer screen class

  * contained in the TDK.<br>

  *

  * @author <a href="mailto:rkoenig@chez.com">Regis Koenig</a>

  * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>

  * @version $Id: RawScreen.java 1773378 2016-12-09 13:19:59Z tv $

  */

 public abstract class RawScreen extends Screen

 {

     /**

      * Build the Screen.  This method actually makes a call to the

      * doOutput() method in order to generate the Screen content.

      *

      * @param pipelineData Turbine information.

      * @return A ConcreteElement.

      * @throws Exception a generic exception.

      */

     @Override

     protected final String doBuild(PipelineData pipelineData)

             throws Exception

     {

         RunData data = getRunData(pipelineData);

         data.getResponse().setContentType(getContentType(pipelineData));

         data.declareDirectResponse();

         doOutput(pipelineData);

         return null;

     }

     /**

      * Set the content type.  This method should be overridden to

      * actually set the real content-type header of the output.

      *

      * @param pipelineData Turbine information.

      * @return A String with the content type.

      */

     protected abstract String getContentType(PipelineData pipelineData);

     /**

      * Actually output the dynamic content.  The OutputStream can be

      * accessed like this: <pre>OutputStream out =

      * data.getResponse().getOutputStream();</pre>.

      *

      * @param pipelineData Turbine information.

      * @throws Exception a generic exception.

      */

     protected abstract void doOutput(PipelineData pipelineData) throws Exception;

     /**

      * The layout must be set to null.

      *

      * @param pipelineData Turbine information.

      * @return A null String.

      */

     @Override

     public final String getLayout(PipelineData pipelineData)

     {

         return null;

     }

 }