CornerRadius

 using cAlgo.API;
 namespace cAlgo
 {
     // This sample indicator shows how to use the rectangle corner radius to create a round corner rectangle
     [Indicator(IsOverlay = true, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
     public class RectangleCornerRadiusSample : Indicator
     {
         protected override void Initialize()
         {
             var rectangle = new Rectangle
             {
                 RadiusX = 20,
                 RadiusY = 20,
                 HorizontalAlignment = HorizontalAlignment.Center,
                 VerticalAlignment = VerticalAlignment.Center,
                 Width = 200,
                 Height = 150,
                 FillColor = Color.FromArgb(100, Color.Red),
                 StrokeColor = Color.Yellow
             };
             Chart.AddControl(rectangle);
         }
         public override void Calculate(int index)
         {
         }
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 from cAlgo.API import *
 class Test():
     def initialize(self):
         rectangle = Rectangle()
         rectangle.RadiusX = 20
         rectangle.RadiusY = 20
         rectangle.HorizontalAlignment = HorizontalAlignment.Center
         rectangle.VerticalAlignment = VerticalAlignment.Center
         rectangle.Width = 200
         rectangle.Height = 150
         rectangle.FillColor = Color.FromArgb(100, Color.Red)
         rectangle.StrokeColor = Color.Yellow
         api.Chart.AddControl(rectangle)