JavaFX manually set NumberAxis ticks - javafx

Question

I have a LineChart that displays a market indicator such as this one:
As you see, what is interesting when using this kind of indicator is when the indicator is above or below threshold lines.
I want to do exactly as shown on the picture above: only have ticks on the YAxis at given values (middle, upper limit, lower limit).
Is it possible?

Answer 1

Following #kleopatra advice in the comments, I implemented my own NumberAxis:
public class FixedTicksAxis extends ValueAxis<Number> {
// List of ticks
private final List<Number> ticks;
// Formatter
private NumberAxis.DefaultFormatter defaultFormatter;
public FixedTicksAxis(Number... ticks) {
super();
this.ticks = Arrays.asList(ticks);
this.defaultFormatter = new NumberAxis.DefaultFormatter(new NumberAxis());
}
#Override
protected List<Number> calculateMinorTickMarks() {
return new ArrayList<>();
}
#Override
protected void setRange(Object range, boolean animate) {
final double[] rangeProps = (double[]) range;
final double lowerBound = rangeProps[0];
final double upperBound = rangeProps[1];
final double scale = rangeProps[2];
setLowerBound(lowerBound);
setUpperBound(upperBound);
currentLowerBound.set(lowerBound);
setScale(scale);
}
#Override
protected Object getRange() {
return new double[]{
getLowerBound(),
getUpperBound(),
getScale(),
};
}
#Override
protected List<Number> calculateTickValues(double length, Object range) {
return ticks;
}
#Override
protected String getTickMarkLabel(Number value) {
StringConverter<Number> formatter = getTickLabelFormatter();
if (formatter == null) formatter = defaultFormatter;
return formatter.toString(value);
}
}
NumberAxis is final, so I can't subclass it.
I didn't want to copy/paste the content of NumberAxis, but I cannot use a delegate for the protected methods, so I did not find any other way than copy/pasting...
But it works, using:
FixedTicksAxis yAxis = new FixedTicksAxis(30, 50, 70);
We get: