--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/flys-artifacts/src/main/java/org/dive4elements/river/jfree/JFreeUtil.java	Thu Apr 25 12:06:39 2013 +0200
@@ -0,0 +1,143 @@
+package org.dive4elements.river.jfree;
+
+import java.awt.Shape;
+import java.awt.geom.Rectangle2D;
+import java.util.Iterator;
+import java.util.Random;
+
+import org.apache.log4j.Logger;
+import org.jfree.chart.entity.ChartEntity;
+import org.jfree.chart.entity.EntityCollection;
+import org.w3c.dom.Document;
+
+import org.dive4elements.river.artifacts.math.Function;
+
+public class JFreeUtil {
+
+    private static final Logger logger = Logger.getLogger(JFreeUtil.class);
+
+    /** Do not instantiate. */
+    private JFreeUtil() {
+    }
+
+
+    /**
+     * True if \param hotspot collides with a Entity in \param entities.
+     * @param hotspot Shape to compare against other shapes (bounds only).
+     * @param entities entities against which to compare shape.
+     * @param exclusiveEntityClass If not null, consider only entities of
+     *        given class.
+     * @return true if a collision (non-zero intersection) exists between
+     *        shapes.
+     */
+    public static boolean collides(Shape hotspot, EntityCollection entities,
+        Class exclusiveEntityClass) {
+        if (entities == null) return false;
+
+        Rectangle2D hotspotBox = hotspot.getBounds2D();
+
+        for (Iterator i = entities.iterator(); i.hasNext(); ) {
+            Object next = i.next();
+            ChartEntity entity = (ChartEntity) next;
+            if (exclusiveEntityClass == null
+                || exclusiveEntityClass.isInstance(entity))
+                {
+                if (entity.getArea().intersects(hotspotBox)) {
+                    // Found collision, early stop.
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+
+    /**
+     * This function samples a randomized line that contains of x and y values
+     * between <i>startX</i>, <i>endX</i>, <i>startY</i> and <i>endY</i>. The
+     * number of points in the line is specified by <i>num</i>.
+     *
+     * @param num The number of points in the line.
+     * @param startX The min value of the x values.
+     * @param endX The max value of the x values.
+     * @param startY The min value of the y values.
+     * @param endY The max value of the y values.
+     * @return an array with [allX-values, allY-values].
+     * @throws IllegalArgumentException
+     */
+    public static double[][] randomizeLine(
+        int    num,
+        double startX,
+        double endX,
+        double startY,
+        double endY
+    ) throws IllegalArgumentException
+    {
+        if (num <= 0) {
+            throw new IllegalArgumentException("Parameter 'num' has to be > 0");
+        }
+
+        Random random = new Random();
+
+        double[] x = new double[num];
+        double[] y = new double[num];
+
+        for (int i = 0; i < num; i++) {
+            double xFac = random.nextDouble();
+            double yFac = random.nextDouble();
+
+            x[i] = startX + xFac * (endX - startX);
+            y[i] = startY + yFac * (endY - startY);
+
+            logger.debug("Created new point: " + x[i] + "|" + y[i]);
+        }
+
+        return new double[][] { x, y };
+    }
+
+
+    public static StyledXYSeries sampleFunction2D(
+        Function func,
+        Document theme,
+        String   seriesKey,
+        int      samples,
+        double   start,
+        double   end
+    ) {
+        StyledXYSeries series = new StyledXYSeries(seriesKey, theme);
+
+        double step = (end - start) / (samples - 1);
+
+        for (int i = 0; i < samples; i++) {
+            double x = start + (step * i);
+            series.add(x, func.value(x));
+        }
+
+        return series;
+    }
+
+    public static StyledXYSeries sampleFunction2DPositive(
+        Function func,
+        Document theme,
+        String   seriesKey,
+        int      samples,
+        double   start,
+        double   end
+    ) {
+        StyledXYSeries series = new StyledXYSeries(seriesKey, theme);
+
+        double step = (end - start) / (samples - 1);
+
+        for (int i = 0; i < samples; i++) {
+            double x = start + (step * i);
+            double v = func.value(x);
+            if (x > 0d && v > 0d) {
+                series.add(x, v);
+            }
+        }
+
+        return series;
+    }
+}
+// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :