// Copyright 2004, 2005 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 java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import org.apache.hivemind.util.Defense;
import org.apache.tapestry.IComponent;
import org.apache.tapestry.IPage;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.engine.IEngineService;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.error.RequestExceptionReporter;
import org.apache.tapestry.services.LinkFactory;
import org.apache.tapestry.services.ServiceConstants;
import org.apache.tapestry.util.ContentType;
import org.apache.tapestry.web.WebResponse;
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
* @since 1.0.10
*/
public class ChartService implements IEngineService
{
public static final String SERVICE_NAME = "chart";
/** @since 4.0 */
private RequestExceptionReporter _exceptionReporter;
/** @since 4.0 */
private LinkFactory _linkFactory;
/** @since 4.0 */
private WebResponse _response;
public ILink getLink(IRequestCycle cycle, Object parameter)
{
Defense.isAssignable(parameter, IComponent.class, "parameter");
IComponent component = (IComponent) parameter;
Map parameters = new HashMap();
parameters.put(ServiceConstants.SERVICE, SERVICE_NAME);
parameters.put(ServiceConstants.PAGE, component.getPage().getPageName());
parameters.put(ServiceConstants.COMPONENT, component.getIdPath());
return _linkFactory.constructLink(cycle, parameters, true);
}
public void service(IRequestCycle cycle) throws IOException
{
String pageName = cycle.getParameter(ServiceConstants.PAGE);
String componentId = cycle.getParameter(ServiceConstants.COMPONENT);
IPage page = cycle.getPage(pageName);
IComponent component = page.getNestedComponent(componentId);
try
{
IChartProvider provider = (IChartProvider) component;
Chart chart = provider.getChart();
OutputStream output = _response.getOutputStream(new ContentType("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)
{
_exceptionReporter.reportRequestException("Component " + component.getExtendedId()
+ " does not implement IChartProvider.", ex);
return;
}
catch (Throwable ex)
{
_exceptionReporter.reportRequestException("Error creating JPEG stream.", ex);
return;
}
return;
}
public String getName()
{
return SERVICE_NAME;
}
/** @since 4.0 */
public void setExceptionReporter(RequestExceptionReporter exceptionReporter)
{
_exceptionReporter = exceptionReporter;
}
/** @since 4.0 */
public void setLinkFactory(LinkFactory linkFactory)
{
_linkFactory = linkFactory;
}
/** @since 4.0 */
public void setResponse(WebResponse response)
{
_response = response;
}
}