jFreeChart GroupedStackedBarRenderer Sublabel alignment in vertical mode

Question

I'm having a small layout problem with jFreeChart (1.0.14, latest maven version). As images do more than words here:

note the vertical displacement of the bars relative to the sublabels "A", "B", "C", "D". I'm not sure if this is a bug or a mis-configuration. See the code attached below to reproduce.

This code is taken out of my current project, thus there might be some unnecessary stuff in there.

package de.test;

import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Map;
import java.util.Random;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

import javax.swing.JFrame;
import javax.swing.JMenuBar;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryLabelPosition;
import org.jfree.chart.axis.CategoryLabelPositions;
import org.jfree.chart.axis.CategoryLabelWidthType;
import org.jfree.chart.axis.SubCategoryAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.GroupedStackedBarRenderer;
import org.jfree.data.KeyToGroupMap;
import org.jfree.data.category.DefaultCategoryDataset;
import org.jfree.text.TextBlockAnchor;
import org.jfree.ui.RectangleAnchor;
import org.jfree.ui.TextAnchor;

public class MainFrame extends JFrame {
    private static final long serialVersionUID = 5309704066433738856L;
    private ChartPanel panel;

    public static void main(String[] args) {
    new MainFrame();
    }

    public MainFrame() {
    JMenuBar menuBar = new JMenuBar();

    setDefaultCloseOperation(EXIT_ON_CLOSE);

    JFreeChart chart = ChartFactory.createStackedBarChart("", "", "", null, PlotOrientation.HORIZONTAL, false, true, false);
    chart.setBackgroundPaint(getBackground());
    chart.setTextAntiAlias(true);
    panel = new ChartPanel(chart, 400, 400, 100, 100, 1000, 1000, true, false, false, true, false, false);

    Set<String> subCategories = new TreeSet<>();
    GroupedStackedBarRenderer groupedStackedBarRenderer = new GroupedStackedBarRenderer();
    groupedStackedBarRenderer.setDrawBarOutline(true);

    GradientPaint billPaint = new GradientPaint(0.0F, 0.0F, Color.GREEN.darker(), 0.0F, 0.0F, Color.GREEN);
    GradientPaint creditPaint = new GradientPaint(0.0F, 0.0F, Color.RED.darker(), 0.0F, 0.0F, Color.RED);

    SubCategoryAxis subCategoryAxis = new SubCategoryAxis(null);
    subCategoryAxis.setCategoryLabelPositions(CategoryLabelPositions.replaceLeftPosition( //
        subCategoryAxis.getCategoryLabelPositions(), //
        new CategoryLabelPosition(RectangleAnchor.CENTER, TextBlockAnchor.BOTTOM_CENTER, TextAnchor.BOTTOM_CENTER, -Math.PI / 2,
            CategoryLabelWidthType.CATEGORY, 1f)));
    subCategoryAxis.setMinorTickMarksVisible(false);
    subCategoryAxis.setAxisLineVisible(false);
    subCategoryAxis.setTickLabelFont(subCategoryAxis.getLabelFont().deriveFont(Font.BOLD));
    KeyToGroupMap keyToGroupMap = new KeyToGroupMap();

    Map<String, Map<String, Map<String, Double>>> map = generateRandomSet(new HashSet<>(Arrays.asList("ab", "cd", "ef", "gh")),
        new HashSet<>(Arrays.asList("A", "B", "C", "D")));
    DefaultCategoryDataset dataset = new DefaultCategoryDataset();
    for (String employee : map.keySet()) {
        Map<String, Map<String, Double>> classMap = map.get(employee);
        for (String serviceClass : classMap.keySet()) {
        Map<String, Double> typeMap = classMap.get(serviceClass);
        subCategories.add(serviceClass.toString());
        Double billValue = typeMap.containsKey("RE") ? (Double) typeMap.get("RE") : 0D;
        Double creditNoteValue = typeMap.containsKey("GU") ? (Double) typeMap.get("GU") : 0D;
        Double effectiveValue = Math.max(0, billValue - creditNoteValue);
        dataset.addValue(effectiveValue, serviceClass + " (RE)", employee);
        dataset.addValue(creditNoteValue, serviceClass + " (GU)", employee);
        }
    }
    CategoryPlot categoryPlot = (CategoryPlot) panel.getChart().getPlot();
    categoryPlot.setDataset(dataset);
    categoryPlot.setDomainAxis(subCategoryAxis);
    categoryPlot.setRenderer(groupedStackedBarRenderer);

    int counter = 0;
    for (String subCategory : subCategories) {
        groupedStackedBarRenderer.setSeriesPaint(counter * 2, billPaint);
        groupedStackedBarRenderer.setSeriesPaint(counter++ * 2 + 1, creditPaint);
        keyToGroupMap.mapKeyToGroup(subCategory + " (RE)", subCategory);
        keyToGroupMap.mapKeyToGroup(subCategory + " (GU)", subCategory);
        subCategoryAxis.addSubCategory(subCategory);
    }
    groupedStackedBarRenderer.setSeriesToGroupMap(keyToGroupMap);

    setJMenuBar(menuBar);
    add(panel);

    setTitle("main.title");

    pack();
    setVisible(true);

    }

    private Map<String, Map<String, Map<String, Double>>> generateRandomSet(Set<String> emplNames, Set<String> subNames) {
    Random rnd = new Random();
    Map<String, Map<String, Map<String, Double>>> result = new TreeMap<>();
    for (String empl : emplNames) {
        Map<String, Map<String, Double>> emplData = new TreeMap<>();
        for (String sub : subNames) {
        Map<String, Double> subData = new TreeMap<>();
        subData.put("RE", rnd.nextDouble() * 1000 + 1000);
        subData.put("GU", rnd.nextDouble() * 1000);
        emplData.put(sub, subData);
        }
        result.put(empl, emplData);
    }
    return result;
    }
}

Answer 1

From source code of new KeyToGroupMap(), we can see that if default group is not specified, it will use "Default Group" as the default group. And this implicit default group will be counted in getGroupCount() function.

GroupedStackedBarRenderer will calculate bar width, margins, and etc using group count. Possibly, one implicit group has been added when drawing bars. So the labels misalign bars.

Fix: use A as default group when creating KeyToGroupMap: KeyToGroupMap keyToGroupMap = new KeyToGroupMap("A");

By the way, I am not sure it is a bug or not.

/**
 * Creates a new map with a default group named 'Default Group'.
 */
public KeyToGroupMap() {
    this("Default Group");
}

/**
 * Creates a new map with the specified default group.
 *
 * @param defaultGroup  the default group (<code>null</code> not permitted).
 */
public KeyToGroupMap(Comparable defaultGroup) {
    if (defaultGroup == null) {
        throw new IllegalArgumentException("Null 'defaultGroup' argument.");
    }
    this.defaultGroup = defaultGroup;
    this.groups = new ArrayList();
    this.keyToGroupMap = new HashMap();
}

/**
 * Returns the number of groups in the map.
 *
 * @return The number of groups in the map.
 */
public int getGroupCount() {
    return this.groups.size() + 1;
}