getAnnotationDatum method
Generates a datum that describes an annotation. This can be implemented to customize annotation positioning.
We can't use Axis
Implementation
@override
DatumAnnotation getAnnotationDatum(Axis<Object> axis) {
// Remove floating point rounding errors by rounding to 2 decimal places of
// precision. The difference in the canvas is negligible.
final position = (axis.getLocation(value)! * 100).round() / 100;
return DatumAnnotation(
startPosition: position, endPosition: position, axisType: axisType);
}