calcMinMax method
Calculates the y-min and y-max value and the y-delta and x-delta value
Implementation
@override
void calcMinMax() {
xAxis!.calculate(getData()!.xMin, getData()!.xMax);
// calculate axis range (min / max) according to provided data
_axisLeft!.calculate(getData()!.getYMin2(AxisDependency.left),
getData()!.getYMax2(AxisDependency.left));
_axisRight!.calculate(getData()!.getYMin2(AxisDependency.right),
getData()!.getYMax2(AxisDependency.right));
}