How to achieve pixel perfect rendering with bar chart

[RedShift1]

Hello

I'm trying to achieve a pixel perfect bar chart (no anti-aliasing effects, etc...). However with my current code, at some chart widths, the bars are not always equal size, for example:

Notice how bars D and E are 22 pixels wide, whilst the rest are 21 pixels wide. The spacing between the bars is also inconsistent. How can I prevent this from happening?

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtils;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.*;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.chart.ui.RectangleInsets;
import org.jfree.data.category.DefaultCategoryDataset;

import java.awt.*;
import java.io.File;
import java.io.IOException;

public class PixelPerfect2
{
    public static void main(String[] args) throws IOException
    {
        final DefaultCategoryDataset dataset = new DefaultCategoryDataset();

        dataset.addValue(20, "", "A 21px");
        dataset.addValue(20, "", "B 21px");
        dataset.addValue(20, "", "C 21px");
        dataset.addValue(20, "", "D 22px");
        dataset.addValue(20, "", "E 22px");
        dataset.addValue(20, "", "F 21px");
        dataset.addValue(20, "", "G 21px");
        dataset.addValue(20, "", "H 21px");

        final JFreeChart chart = ChartFactory.createStackedBarChart(null, "", "kWh", dataset);

        chart.setAntiAlias(false);
        chart.setTextAntiAlias(true);
        chart.removeLegend();

        final CategoryPlot plot = (CategoryPlot) chart.getPlot();

        final AxisSpace axisSpace = new AxisSpace();
        axisSpace.setBottom(60);
        axisSpace.setLeft(60);
        axisSpace.setRight(0);
        axisSpace.setTop(5);

        plot.setFixedDomainAxisSpace(axisSpace);
        plot.setFixedRangeAxisSpace(axisSpace);
        plot.setInsets(RectangleInsets.ZERO_INSETS);
        plot.setRangeGridlineStroke(new BasicStroke(1));
        plot.setRangeZeroBaselineVisible(true);
        plot.setRangeZeroBaselinePaint(Color.LIGHT_GRAY);

        final ValueAxis rangeAxis = plot.getRangeAxis();

        rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
        rangeAxis.setAxisLinePaint(Color.WHITE);
        rangeAxis.setAxisLineStroke(new BasicStroke(1));
        rangeAxis.setTickMarksVisible(true);
        rangeAxis.setTickMarkOutsideLength(4);
        rangeAxis.setTickMarkPaint(Color.DARK_GRAY);

        final CategoryAxis domainAxis = plot.getDomainAxis();

        domainAxis.setCategoryLabelPositions(CategoryLabelPositions.UP_45);
        domainAxis.setMaximumCategoryLabelWidthRatio(3);
        domainAxis.setAxisLinePaint(Color.WHITE);
        domainAxis.setAxisLineStroke(new BasicStroke(1));
        domainAxis.setTickMarksVisible(false);

        final BarRenderer renderer = (BarRenderer) plot.getRenderer();

        renderer.setDrawBarOutline(false);
        renderer.setShadowVisible(false);
        renderer.setShadowXOffset(0);
        renderer.setShadowYOffset(0);
        renderer.setSeriesPaint(0, new Color(38, 185, 154));
        renderer.setSeriesPaint(1, Color.decode("#03586A"));
        renderer.setDrawBarOutline(false);
        renderer.setSeriesOutlinePaint(0, Color.BLACK);
        renderer.setSeriesOutlinePaint(1, Color.BLACK);

        plot.setShadowGenerator(null);

        ChartUtils.saveChartAsPNG(new File("pixel_chart.png"), chart, 310, 240);
        System.out.println("Chart saved as pixel_chart.png");
    }
}

[trashgod]

You might look at adjusting the width and height values passed to ChartUtils.saveChartAsPNG(). An integral multiple of the number of bars would be a place to start.