JFreeChart StackedXYAreaRenderer causes “crimp” in chart

Question

I\'m using JFreeChart to show a stacked line chart of two sets of data over time, in this example dogs and cats.

import jav         


        

Answer 1

ChartFactory.createStackedXYAreaChart() instantiates StackedXYAreaRenderer2 to avoid this problem. Your example replaces it with an instance of StackedXYAreaRenderer. Either,

• Use the factory's renderer and a custom DateAxis.

  private JFreeChart createChart(TimeTableXYDataset chartData) {
      JFreeChart chart = ChartFactory.createStackedXYAreaChart(
          "Dogs and Cats", "Time", "Count", chartData,
          PlotOrientation.VERTICAL, false, true, false);
      DateAxis dateAxis = new DateAxis();
      dateAxis.setDateFormatOverride(new SimpleDateFormat("HH:mm"));
      dateAxis.setTickLabelFont(dateAxis.getTickLabelFont().deriveFont(20f));
      XYPlot plot = (XYPlot) chart.getPlot();
      plot.setDomainAxis(dateAxis);
      return chart;
  }
  

• Recapitulate the factory, as shown here, in your createChart() method.

  private JFreeChart createChart(TimeTableXYDataset chartData) {
      DateAxis dateAxis = new DateAxis("Time");
      dateAxis.setDateFormatOverride(new SimpleDateFormat("HH:mm"));
      dateAxis.setTickLabelFont(dateAxis.getTickLabelFont().deriveFont(20f));
      NumberAxis yAxis = new NumberAxis("Count");
      XYToolTipGenerator toolTipGenerator = new StandardXYToolTipGenerator();
      StackedXYAreaRenderer2 renderer = new StackedXYAreaRenderer2(
          toolTipGenerator, null);
      renderer.setOutline(true);
      XYPlot plot = new XYPlot(chartData, dateAxis, yAxis, renderer);
      plot.setOrientation(PlotOrientation.VERTICAL);
      plot.setRangeAxis(yAxis);  // forces recalculation of the axis range
      JFreeChart chart = new JFreeChart("Dogs and Cats",
          JFreeChart.DEFAULT_TITLE_FONT, plot, false);
      new StandardChartTheme("JFree").apply(chart);
      return chart;
  }
  

Can you expand a little bit on why the StackedXYRenderer causes that crimp?

The author writes, "StackedXYAreaRenderer2 uses a different drawing approach, calculating a polygon for each data point and filling that." In contrast, StackedXYAreaRenderer appears to close a single Shape by connecting the endpoints with a straight line.