// Copyright 2004 The Apache Software Foundation
//
// Licensed 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.
package org.apache.tapestry.workbench.chart;
import java.io.IOException;
import javax.servlet.ServletException;
import org.apache.tapestry.IComponent;
import org.apache.tapestry.IPage;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.engine.AbstractService;
import org.apache.tapestry.engine.IEngineServiceView;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.request.ResponseOutputStream;
import org.jCharts.Chart;
import org.jCharts.encoders.JPEGEncoder13;
/**
* ServiceLink that works with a {@link Chart} to dynamically render
* a chart as a JPEG. This is a very limited implementation; a full version
* would include features such as setting the size of the image, and more flexibility
* in defining where the {@link Chart} instance is obtained from.
*
* @author Howard Lewis Ship
* @version $Id: ChartService.java,v 1.7 2004/02/19 17:37:50 hlship Exp $
* @since 1.0.10
*
**/
public class ChartService extends AbstractService
{
public static final String SERVICE_NAME = "chart";
public ILink getLink(IRequestCycle cycle, IComponent component, Object[] parameters)
{
String[] context;
String pageName = component.getPage().getPageName();
String idPath = component.getIdPath();
if (idPath != null)
{
context = new String[2];
context[1] = idPath;
}
else
context = new String[1];
context[0] = pageName;
return constructLink(cycle, SERVICE_NAME, context, null, true);
}
public void service(
IEngineServiceView engine,
IRequestCycle cycle,
ResponseOutputStream output)
throws ServletException, IOException
{
String context[] = getServiceContext(cycle.getRequestContext());
String pageName = context[0];
String idPath = (context.length == 1) ? null : context[1];
IPage page = cycle.getPage(pageName);
IComponent component = (idPath == null) ? page : page.getNestedComponent(idPath);
try
{
IChartProvider provider = (IChartProvider) component;
Chart chart = provider.getChart();
output.setContentType("image/jpeg");
// I've seen a few bits of wierdness (including a JVM crash) inside this code.
// Hopefully, its a multi-threading problem that can be resolved
// by synchronizing.
synchronized (this)
{
JPEGEncoder13.encode(chart, 1.0f, output);
}
}
catch (ClassCastException ex)
{
engine.reportException(
"Component " + component.getExtendedId() + " does not implement IChartProvider.",
ex);
return;
}
catch (Throwable ex)
{
engine.reportException("Error creating JPEG stream.", ex);
return;
}
return;
}
public String getName()
{
return SERVICE_NAME;
}
}