TickLabeller based on the formatting and bounding-box capabilities of the GrannyTextRenderer. This class by default creates a DatumFormatter for the tickDescriptor it receives, and then uses the grannyFormat method to get the label. This object is useful as-is, but provides an easy way to get complex labels (e.g. TCAs) by overriding init and getLabel.
the formatter.
sets the ticks and DatumFormatter before drawing.
override the formatter in the TickVDescriptor.