DefaultChartGenerator.java

/*
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.xwiki.chart.internal;

import java.io.IOException;
import java.util.List;
import java.util.Map;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Provider;
import javax.inject.Singleton;

import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.Plot;
import org.xwiki.chart.ChartCustomizer;
import org.xwiki.chart.ChartGenerator;
import org.xwiki.chart.ChartGeneratorException;
import org.xwiki.chart.internal.plot.PlotGenerator;
import org.xwiki.chart.model.ChartModel;
import org.xwiki.component.annotation.Component;
import org.xwiki.component.manager.ComponentLookupException;
import org.xwiki.component.manager.ComponentManager;

/**
 * The default implementation of {@link ChartGenerator} component interface which utilizes the JFreeChart charting
 * library.
 * 
 * @version $Id: 07b85af85828ad693a871decbab950e14cb7d73a $
 * @since 2.0M1
 */
@Component
@Singleton
public class DefaultChartGenerator implements ChartGenerator
{
    /**
     * Used to lookup plot generators dynamically.
     */
    @Inject
    @Named("context")
    private Provider<ComponentManager> contextComponentManager;

    @Inject
    private Provider<List<ChartCustomizer>> customizerProvider;

    @Override
    public byte[] generate(ChartModel model, Map<String, String> parameters) throws ChartGeneratorException
    {
        setDefaultParams(parameters);
        String type = parameters.get(TYPE_PARAM);
        String title = parameters.get(TITLE_PARAM);

        PlotGenerator generator;
        try {
            generator = contextComponentManager.get().getInstance(PlotGenerator.class, type);
        } catch (ComponentLookupException e) {
            throw new ChartGeneratorException(String.format("No such chart type : [%s].", type), e);
        }

        Plot plot = generator.generate(model, parameters);
        JFreeChart jfchart = new JFreeChart(title, plot);

        // Run customizations
        for (ChartCustomizer customizer : this.customizerProvider.get()) {
            customizer.customize(jfchart, parameters);
        }

        int width = Integer.parseInt(parameters.get(WIDTH_PARAM));
        int height = Integer.parseInt(parameters.get(HEIGHT_PARAM));
        try {
            return ChartUtilities.encodeAsPNG(jfchart.createBufferedImage(width, height));
        } catch (IOException ex) {
            throw new ChartGeneratorException("Error while png encoding the chart image.");
        }
    }

    /**
     * Sets up default values for certain parameters, if they are not provided.
     * 
     * @param parameters the parameter set which the values are to be put into
     */
    public void setDefaultParams(Map<String, String> parameters)
    {
        setParam(SERIES_PARAM, "rows", parameters);
        setParam(WIDTH_PARAM, "400", parameters);
        setParam(HEIGHT_PARAM, "300", parameters);
    }

    /**
     * Sets up values in a map, unless they already exist.
     * 
     * @param key the key
     * @param value the corresponding value
     * @param map the map in which the values are put
     */
    private static void setParam(String key, String value, Map<String, String> map)
    {
        if (!map.containsKey(key)) {
            map.put(key, value);
        }
    }
}