--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/de/intevation/flys/exports/InfoGeneratorHelper.java	Wed Jun 01 08:01:07 2011 +0000
@@ -0,0 +1,160 @@
+package de.intevation.flys.exports;
+
+import java.awt.geom.AffineTransform;
+import java.awt.geom.NoninvertibleTransformException;
+import java.awt.geom.Rectangle2D;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+
+import org.apache.log4j.Logger;
+
+import org.jfree.chart.ChartRenderingInfo;
+import org.jfree.chart.JFreeChart;
+import org.jfree.chart.plot.XYPlot;
+import org.jfree.data.Range;
+
+import de.intevation.artifacts.common.ArtifactNamespaceContext;
+import de.intevation.artifacts.common.utils.XMLUtils;
+import de.intevation.artifacts.common.utils.XMLUtils.ElementCreator;
+
+
+/**
+ * This class helps generating chart info documents.
+ *
+ * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
+ */
+public class InfoGeneratorHelper {
+
+    private static final Logger logger =
+        Logger.getLogger(InfoGeneratorHelper.class);
+
+
+    private InfoGeneratorHelper() {
+    }
+
+
+    /**
+     * Triggers the creation of the chart info document.
+     *
+     * @param chart The JFreeChart chart.
+     * @param info An info object that has been created while chart creation.
+     *
+     * @return the info document.
+     */
+    public static Document createInfoDocument(
+        JFreeChart         chart,
+        ChartRenderingInfo info)
+    {
+        logger.debug("InfoGeneratorHelper.createInfoDocument");
+
+        Document doc = XMLUtils.newDocument();
+
+        ElementCreator cr = new ElementCreator(
+            doc,
+            ArtifactNamespaceContext.NAMESPACE_URI,
+            ArtifactNamespaceContext.NAMESPACE_PREFIX);
+
+        Element chartinfo = cr.create("chartinfo");
+
+        chartinfo.appendChild(createTransformationElement(cr, chart, info));
+
+        doc.appendChild(chartinfo);
+
+        return doc;
+    }
+
+
+    /**
+     * This method appends the values of a transformation matrix to transform
+     * image pixel coordinates into chart coordinates.
+     *
+     * @param cr The ElementCreator.
+     * @param chart The chart object.
+     * @param info The ChartRenderingInfo that is filled while chart creation.
+     *
+     * @return an element that contains one or more transformation matrix.
+     */
+    protected static Element createTransformationElement(
+        ElementCreator     cr,
+        JFreeChart         chart,
+        ChartRenderingInfo info)
+    {
+        logger.debug("InfoGeneratorHelper.createTransformationElement");
+
+        Element tf = cr.create("transformation-matrix");
+
+        Rectangle2D dataArea = info.getPlotInfo().getDataArea();
+
+        XYPlot plot   = (XYPlot) chart.getPlot();
+        Range  xRange = plot.getDomainAxis().getRange();
+        Range  yRange = plot.getRangeAxis().getRange();
+
+        double[] tm = createTransformationMatrix(dataArea, xRange, yRange);
+
+        cr.addAttr(tf, "sx", String.valueOf(tm[0]), true);
+        cr.addAttr(tf, "sy", String.valueOf(tm[1]), true);
+        cr.addAttr(tf, "tx", String.valueOf(tm[2]), true);
+        cr.addAttr(tf, "ty", String.valueOf(tm[3]), true);
+
+        return tf;
+    }
+
+
+    /**
+     * This method determines a transformation matrix to transform pixel
+     * coordinates of the chart image into chart coordinates.
+     *
+     * @param dataArea The rectangle that contains the data points of the chart.
+     * @param xRange The x axis range.
+     * @param yRange The y axis range.
+     *
+     * @return a double array as follows: [sx, sy, tx, ty].
+     */
+    protected static double[] createTransformationMatrix(
+        Rectangle2D dataArea,
+        Range       xRange,
+        Range       yRange)
+    {
+        double offsetX = dataArea.getX();
+        double width   = dataArea.getWidth() - 1;
+        double offsetY = dataArea.getY();
+        double height  = dataArea.getHeight();
+
+        double lowerX  = xRange.getLowerBound();
+        double upperX  = xRange.getUpperBound();
+        double lowerY  = yRange.getLowerBound();
+        double upperY  = yRange.getUpperBound();
+
+        double dMoveX = upperX - lowerX;
+        double fMoveX = width * lowerX;
+        double dMoveY = lowerY - upperY;
+        double fMoveY = height * upperY;
+
+        AffineTransform t1 = AffineTransform.getTranslateInstance(
+                offsetX - ( fMoveX / dMoveX ),
+                offsetY - ( fMoveY / dMoveY ) );
+
+        AffineTransform t2 = AffineTransform.getScaleInstance(
+                width / (upperX - lowerX),
+                height / (lowerY - upperY));
+
+        t1.concatenate(t2);
+
+        try {
+            t1.invert();
+
+            double[] c = new double[6];
+            t1.getMatrix(c);
+
+            return new double[] { c[0], c[3], c[4], c[5] };
+        }
+        catch (NoninvertibleTransformException e) {
+            // do nothing
+            logger.warn("Matrix is not invertible.");
+        }
+
+        return new double[] { 1d, 1d, 0d, 0d };
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :