Java tutorial
/* * GeoTools - The Open Source Java GIS Toolkit * http://geotools.org * * (C) 2002-2008, Open Source Geospatial Foundation (OSGeo) * * This library 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; * version 2.1 of the License. * * This library 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. */ package org.geotools.renderer.chart; import java.awt.Graphics2D; import java.awt.geom.Rectangle2D; import java.awt.image.BufferedImage; import java.util.Map; import javax.swing.Icon; import javax.swing.ImageIcon; import org.geotools.renderer.style.ExternalGraphicFactory; import org.jfree.chart.JFreeChart; import org.jfree.eastwood.ChartEngine; import org.jfree.eastwood.Parameters; import org.opengis.feature.Feature; import org.opengis.filter.expression.Expression; /** * Parses Google charts like requests into various kinds of charts. * <p> * Underlying implementation is based on <a href="http://www.jfree.org/eastwood/">Eastwood charts</a> * and <a href="http://www.jfree.org/jfreechart/index.html">JFreeChart</a> * <p> * And example of a valid symbolizer use in SLD is: * <pre> * <ExternalGraphic> * <OnlineResource xlink:href="http://chart?cht=p&amp;chl=male|female&amp;chd=t:${100 * male / (male + female)},${100 * female / (male + female)}&amp;chs=200x100&amp;chf=bg,s,FFFFFF00"/> * <Format>application/chart</Format> * </ExternalGraphic> * </pre> * This request will generate a pie chart representing the percentages of female and male * population using attribute features and CQL expression to buid the percentage value to be * used. * </p> * <p> * For details on the URL format documentation refer to the online * <a href="http://code.google.com/intl/it-IT/apis/chart/">Google charts API</a>. * </p> * <p> * Also mind Eastwood does not implement all of the Google charts API, for example, * Venn diagram and spider diagrams are not supported. Check on the Eastwood project * pages for details. * </p> * @since 2.5.6 * * * * @source $URL$ */ public class ChartGraphicFactory implements ExternalGraphicFactory { public static final String FORMAT = "application/chart"; private static final String HTTP_CHART = "http://chart?"; public Icon getIcon(Feature feature, Expression urlExpression, String format, int size) throws Exception { // evaluate the expression as a string, get the query params String url = urlExpression.evaluate(feature, String.class); if (!validRequest(url, format)) return null; Map params = Parameters.parseQueryString(url.substring(HTTP_CHART.length())); // build the chart, guess its optimal size, return the icon representing it JFreeChart chart = ChartEngine.buildChart(params); int[] chartSize = computeChartSize(size, params); return new ImageIcon(drawChart(chart, chartSize[0], chartSize[1])); } private boolean validRequest(String url, String format) { return FORMAT.equals(format) && url.startsWith(HTTP_CHART); } /** * This method has been provided as a test utility only */ JFreeChart getChart(Feature feature, Expression urlExpression, String format, int size) throws Exception { // evaluate the expression as a string, get the query params String url = urlExpression.evaluate(feature, String.class); if (!validRequest(url, format)) return null; Map params = Parameters.parseQueryString(url.substring(HTTP_CHART.length())); // build the chart, guess its optimal size, return the icon representing it return ChartEngine.buildChart(params); } BufferedImage drawChart(JFreeChart chart, int w, int h) { BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_4BYTE_ABGR); Graphics2D gr = bi.createGraphics(); try { chart.draw(gr, new Rectangle2D.Double(0, 0, w, h)); } finally { gr.dispose(); } return bi; } int[] computeChartSize(int size, Map params) { // We have two size params here, the one coming from SLD, the one coming from the chs // parameter, let's try to respect the SLD one, but keep the form factor coming from // the chs param String[] sizes = (String[]) params.get("chs"); int[] dims = null; if (sizes != null) dims = parseCHS(sizes); if (dims == null && size <= 0) throw new IllegalArgumentException( "Chart size cannot be computed, a SLD size " + "is missing, so is the chs chart param"); if (size > 0) { if (dims == null) { dims = new int[] { size, size }; } else { if (dims[0] > dims[1]) { dims[1] = dims[1] * size / dims[0]; dims[0] = size; } else { dims[0] = dims[0] * size / dims[1]; dims[1] = size; } } } return dims; } /** * Parses the CHS parameter, should be in the form wxh, where w and h are integers and x is the * separator * * @param sizes * @return */ int[] parseCHS(String[] sizes) { int[] dims; dims = new int[2]; String[] xy = sizes[0].split("x"); if (xy.length != 2) throw new IllegalArgumentException( "The chs parameter should be in wxh form, " + "where w and h are measured in pixels"); dims[0] = Integer.parseInt(xy[0]); dims[1] = Integer.parseInt(xy[1]); return dims; } }