onPaint method
Implementation
@override
void onPaint(PaintingContext context, Offset offset) {
  paintSegments(context, offset);
  paintMarkers(context, offset);
  paintDataLabels(context, offset);
  paintTrendline(context, offset);
}@override
void onPaint(PaintingContext context, Offset offset) {
  paintSegments(context, offset);
  paintMarkers(context, offset);
  paintDataLabels(context, offset);
  paintTrendline(context, offset);
}