2

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?

Baked Inhalf
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1 Answers1

2

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);

image

Other implementations of OHLCDataset have corresponding accessors.

trashgod
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  • Ok I was assuming that coordinates (0, 0) would be top left corner on the plot... I will try your code out! – Baked Inhalf Jun 14 '19 at 08:04
  • Oh I see.. the Y-coordinate is `price` and the X-coordinate is in `milliseconds`. So since I use daily chart, my X-values are LARGE, like `3600 * 1000 * 24` – Baked Inhalf Jun 14 '19 at 09:11
  • @BakedInhalf: Exactly; I've updated the fragment to use the target item's period. – trashgod Jun 14 '19 at 16:26