java - Annotations on candlestick chart not working

Question

I'm trying to add annotations to a chart. It seems like it's added, since the size() of the plot's annotations list increases if I add one more. The problem is that it's not being displayed.

OHLCDataset candles = createCandleDataset();

// Create chart
chart = ChartFactory.createCandlestickChart(
    "mychart", "", "", candles, true);

XYPlot plot = (XYPlot) chart.getPlot();        

XYShapeAnnotation a1 = new XYShapeAnnotation(
    new Rectangle2D.Double(10.0, 20.0, 20.0, 30.0),
    new BasicStroke(1.0f), Color.blue);
plot.addAnnotation(a1);

ChartPanel panel = new ChartPanel(chart);
setContentPane(panel);

Any ideas?

Answer 1

The XYShapeAnnotation API says:

The shape coordinates are specified in data space.

The coordinates of your Rectangle2D may be inapparent relative to your actual data. Instead, use coordinates from your OHLCDataset to construct your annotation. Focusing on the second item in series1 in this example, the chart below illustrates retrieving data from the underlying OHLCSeries to create an annotation one period wide and spanning the high/low value.

// series
addSeries1();
OHLCSeries series = seriesCollection.getSeries(0);
OHLCItem item = (OHLCItem) series.getDataItem(1);
RegularTimePeriod t = item.getPeriod();
long x = t.getFirstMillisecond();
long w = t.getLastMillisecond() - t.getFirstMillisecond(); 
double y = item.getLowValue();
double h = item.getHighValue() - y;
XYShapeAnnotation a1 = new XYShapeAnnotation(
    new Rectangle2D.Double(x, y, w, h),
    new BasicStroke(1f), Color.blue
);
chart.getXYPlot().addAnnotation(a1);

Other implementations of OHLCDataset have corresponding accessors.