void DrawAlarmZone(FlexChart chart, IRenderEngine engine, double xmin, double ymin, double xmax, double ymax, Color fill)
{
var pt1 = chart.DataToPoint(new PointF((float)xmin, (float)ymin));
var pt2 = chart.DataToPoint(new PointF((float)xmax, (float)ymax));
engine.SetFill(new SolidBrush(fill));
engine.SetStroke(new SolidBrush(Color.Transparent));
engine.DrawRect(Math.Min(pt1.X, pt2.X), Math.Min(pt1.Y, pt2.Y), Math.Abs(pt2.X - pt1.X), Math.Abs(pt2.Y - pt1.Y));
}
