Returns number of elements in each data set dimension, so i can validate a that all
IAxisPlotDataSets on a ComboChart have the same number of elements, as well as the
number of Axis Labels equal the number of data elements other charts.
This Class is used to recieve callbacks from the chart renderers after they render
their value to the chart, with value meaning their bar, point, line, etc...
To optimze performance of the ImageMap Object, we create it once we know how many data
elements are in the chart which is dependent on the AxisChart or PieChart2D
You do not have to explicitly set a ScaleCalculator implementation as jCharts will
create one, but if you do not like the way Scale ranges are created, you could
create your own implementation of ScaleCalculator and jCharts will use it!
Constructor when using transformed (derived) fonts
The need for this arises because the java metrics classes return either 0 or very strange
values for the width and height of a string (TextLayout, LineMetrics, etc..) when
the font is derived
It would seem to make sense to pass in the min and the max, but we want to allow
people to use custom implementations which will be created when the AxisChart
constructor gets called and we will not have looped the data to find the min
and max yet.