getDiameter method
returns the diameter of the pie- or radar-chart
@return
Implementation
double getDiameter() {
Rect content = Rect.fromLTRB(
viewPortHandler!.getContentRect().left + extraLeftOffset,
viewPortHandler!.getContentRect().top + extraTopOffset,
viewPortHandler!.getContentRect().right - extraRightOffset,
viewPortHandler!.getContentRect().bottom - extraBottomOffset);
return min(content.width, content.height);
}