nextapp.echo2.chart.webcontainer.ChartImageService.java Source code

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Here is the source code for nextapp.echo2.chart.webcontainer.ChartImageService.java

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/* 
 * This file is part of the Echo2 Chart Library.
 * Copyright (C) 2005-2009 NextApp, Inc.
 *
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 */

package nextapp.echo2.chart.webcontainer;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.http.HttpServletRequest;

import org.jfree.chart.JFreeChart;

import nextapp.echo2.app.Extent;
import nextapp.echo2.chart.app.ChartDisplay;
import nextapp.echo2.webcontainer.ContainerInstance;
import nextapp.echo2.webcontainer.RenderContext;
import nextapp.echo2.webcontainer.image.PngEncoder;
import nextapp.echo2.webcontainer.propertyrender.ExtentRender;
import nextapp.echo2.webrender.Connection;
import nextapp.echo2.webrender.ContentType;
import nextapp.echo2.webrender.Service;
import nextapp.echo2.webrender.WebRenderServlet;

/**
 * <code>Service</code> to render chart images.
 */
public class ChartImageService implements Service {

    /**
     * Parameter keys used in generating service URI.
     */
    private static final String[] URI_PARAMETER_KEYS = { "chartId", "v" };

    /**
     * Returns the appropriate URI to display a chart for a specific 
     * <code>ChartDisplay</code> component.
     * 
     * @param rc the relevant <code>RenderContext</code>
     * @param chartDisplay the rendering <code>ChartDisplay</code>
     * @param version the version number of the chart 
     *        (incremented when chart is re-rendered due to an update)
     * @return the URI
     */
    static final String getUri(RenderContext rc, ChartDisplay chartDisplay, int version) {
        return rc.getContainerInstance().getServiceUri(INSTANCE, URI_PARAMETER_KEYS,
                new String[] { chartDisplay.getRenderId(), Integer.toString(version) });
    }

    /**
     * Singleton instance.
     */
    private static final ChartImageService INSTANCE = new ChartImageService();

    static {
        WebRenderServlet.getServiceRegistry().add(INSTANCE);
    }

    /** Self-instantiated singleton. */
    private ChartImageService() {
    }

    /**
     * @see nextapp.echo2.webrender.Service#getId()
     */
    public String getId() {
        return "Echo2Chart.ImageService";
    }

    /**
     * @see nextapp.echo2.webrender.Service#getVersion()
     */
    public int getVersion() {
        return DO_NOT_CACHE;
    }

    /**
     * @see nextapp.echo2.webrender.Service#service(nextapp.echo2.webrender.Connection)
     */
    public void service(Connection conn) throws IOException {
        try {
            ContainerInstance containerInstance = (ContainerInstance) conn.getUserInstance();
            HttpServletRequest request = conn.getRequest();
            String chartId = request.getParameter("chartId");
            ChartDisplay chartDisplay = (ChartDisplay) containerInstance.getApplicationInstance()
                    .getComponentByRenderId(chartId);
            synchronized (chartDisplay) {
                if (chartDisplay == null || !chartDisplay.isRenderVisible()) {
                    throw new IllegalArgumentException("Invalid chart id.");
                }

                int width = ExtentRender.toPixels(
                        (Extent) chartDisplay.getRenderProperty(ChartDisplay.PROPERTY_WIDTH),
                        ChartDisplayPeer.DEFAULT_WIDTH);
                int height = ExtentRender.toPixels(
                        (Extent) chartDisplay.getRenderProperty(ChartDisplay.PROPERTY_HEIGHT),
                        ChartDisplayPeer.DEFAULT_HEIGHT);
                JFreeChart chart = chartDisplay.getChart();
                BufferedImage image;
                synchronized (chart) {
                    image = chart.createBufferedImage(width, height);
                }
                PngEncoder encoder = new PngEncoder(image, true, null, 3);
                conn.setContentType(ContentType.IMAGE_PNG);
                OutputStream out = conn.getOutputStream();
                encoder.encode(out);
            }
        } catch (IOException ex) {
            // Internet Explorer appears to enjoy making half-hearted requests for images, wherein it resets the connection
            // leaving us with an IOException.  This exception is silently eaten.
            ex.printStackTrace();
        }
    }
}