--- a/gnv-artifacts/src/main/java/de/intevation/gnv/chart/DefaultHistogram.java	Wed May 26 17:01:29 2010 +0000
+++ b/gnv-artifacts/src/main/java/de/intevation/gnv/chart/DefaultHistogram.java	Thu May 27 07:41:14 2010 +0000
@@ -1,9 +1,5 @@
 package de.intevation.gnv.chart;
 
-import java.text.NumberFormat;
-import java.text.ParseException;
-
-import java.util.Locale;
 import java.util.Map;
 
 import org.apache.log4j.Logger;
@@ -12,8 +8,6 @@
 
 import org.jfree.chart.plot.XYPlot;
 
-import org.jfree.data.statistics.HistogramDataset;
-
 /**
  * Default implementation of {@link de.intevation.gnv.chart.AbstractHistogram}.
  *
@@ -67,6 +61,8 @@
      */
     protected Map requestParameter;
 
+    protected double[] minmax = null;
+
 
     /**
      * Constructor to create DefaultHistogram objects.
@@ -91,10 +87,13 @@
         // prepare data and create add them to histogram dataset
         String   name   = (String)   data[0];
         double[] values = toDouble((Double[]) data[1]);
-        int      bins   = getBinCount(values);
 
-        HistogramDataset dataset = new HistogramDataset();
-        dataset.addSeries(name, values, bins);
+        double binWidth = getBinWidth(values);
+        int    binCount = getBinCount();
+
+        AdvancedHistogramDataset dataset =
+            new AdvancedHistogramDataset(binCount, binWidth);
+        dataset.addSeries(name, values);
 
         plot.setDataset(0, dataset);
     }
@@ -110,6 +109,9 @@
      * @return Array which contains min and max value
      */
     protected double[] getMinMax(double[] values) {
+        if (minmax != null)
+            return minmax;
+
         double[] minmax = new double[2];
         minmax[0] = Double.MAX_VALUE;
         minmax[1] = Double.MIN_VALUE;
@@ -120,6 +122,8 @@
             minmax[1] = values[i] > minmax[1] ? values[i] : minmax[1];
         }
 
+        this.minmax = minmax;
+
         return minmax;
     }
 
@@ -144,38 +148,21 @@
 
 
     /**
-     * Method to calculate the number of bins this chart should be parted into.
-     * The real calculation takes place in {@link #getBinCountByNumber} and
-     * {@link #getBinCountByWidth}. This method switches between these methods
-     * depending on the object stored in {@link #requestParameter}.
-     *
-     * @param values All values used in this histogram
+     * Method to retrieve the number of bins.
      *
-     * @return Number of bins
+     * @return the number of bins that is specified in <i>requestParameter</i>
+     * or -1 if the number of bins is not the dominant value to calculate the
+     * width of a single bin.
      */
-    protected int getBinCount(double[] values) {
-        String param = (String) requestParameter.get(REQUEST_KEY_BIN_CHOICE);
-
-        if (param != null && param.equalsIgnoreCase(REQUEST_KEY_BIN_WIDTH)) {
-            return getBinCountByWidth(values);
+    protected int getBinCount() {
+        // Return -1 to trigger a calculation of the number of bins in
+        // AdvancedHistogramDataset if the user chose the bin width as dominant
+        // value.
+        String choice = (String) requestParameter.get(REQUEST_KEY_BIN_CHOICE);
+        if (choice != null && choice.equalsIgnoreCase(REQUEST_KEY_BIN_WIDTH)) {
+            return -1;
         }
-        else {
-            return getBinCountByNumber();
-        }
-    }
-
 
-    /**
-     * Method to retrieve the number of bins. If {@link #requestParameter}
-     * contains a valid <code>Integer</code> at
-     * <code>REQUEST_KEY_BIN_COUNT</code> and this is smaller than or equal
-     * {@link #MAXIMAL_BINS}, this value is used. If no valid
-     * <code>Integer</code> is given or if the value in {@link #requestParameter}
-     * is bigger than {@link #MAXIMAL_BINS}, {@link #DEFAULT_BINS} is used.
-     *
-     * @return Number of bins
-     */
-    protected int getBinCountByNumber() {
         int    bins  = -1;
         String param = (String) requestParameter.get(REQUEST_KEY_BIN_COUNT);
 
@@ -196,16 +183,25 @@
 
 
     /**
-     * Serves the number of bins depending on a given width for each bin, but
-     * maximum bin count is limited by {@link #MAXIMAL_BINS}.
+     * Serves width of a single bin.
      *
      * @param values All values in this histogram
      *
-     * @return Number of bins
+     * @return The bin width that is given in <i>requestParameter</i> or -1 if
+     * the bin width is not the dominant value for calculating the number of
+     * bins in the histogram.
      */
-    protected int getBinCountByWidth(double[] values) {
-        int    bins   = -1;
-        String param  = (String) requestParameter.get(REQUEST_KEY_BIN_WIDTH);
+    protected double getBinWidth(double[] values) {
+        // Return -1 to trigger a calculation of the bin width in
+        // AdvancedHistogramDataset if the user chose the number of bins as
+        // dominant value.
+        String choice = (String) requestParameter.get(REQUEST_KEY_BIN_CHOICE);
+        if (choice == null || !choice.equalsIgnoreCase(REQUEST_KEY_BIN_WIDTH)) {
+            return -1;
+        }
+
+        int    bins  = -1;
+        String param = (String) requestParameter.get(REQUEST_KEY_BIN_WIDTH);
 
         double[] minmax     = getMinMax(values);
         double   totalWidth = minmax[1] - minmax[0];
@@ -215,9 +211,14 @@
 
         bins = (int) Math.round(tmpBins);
         bins = bins <= 0 ? DEFAULT_BINS : bins;
-        bins = bins >  MAXIMAL_BINS ? MAXIMAL_BINS : bins;
 
-        return bins;
+        // the calculated number of bins with the given width exceed the maximum
+        // number of bins.
+        if (bins > MAXIMAL_BINS) {
+            return totalWidth / (MAXIMAL_BINS);
+        }
+
+        return binWidth;
     }
 }
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