ChartEllipse

 using cAlgo.API;
 namespace cAlgo
 {
     // This sample indicator draw an ellipse on chart
     [Indicator(IsOverlay = true, TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
     public class ChartEllipseSample : Indicator
     {
         protected override void Initialize()
         {
             Draw();
         }
         public override void Calculate(int index)
         {
             Draw();
         }
         private void Draw()
         {
             var y1 = Bars.HighPrices[Chart.FirstVisibleBarIndex] > Bars.HighPrices[Chart.LastVisibleBarIndex] ? Bars.HighPrices[Chart.FirstVisibleBarIndex] : Bars.HighPrices[Chart.LastVisibleBarIndex];
             var y2 = Bars.LowPrices[Chart.FirstVisibleBarIndex] < Bars.LowPrices[Chart.LastVisibleBarIndex] ? Bars.LowPrices[Chart.FirstVisibleBarIndex] : Bars.LowPrices[Chart.LastVisibleBarIndex];
             var ellipse = Chart.DrawEllipse("ellipse", Chart.FirstVisibleBarIndex, y1, Chart.LastVisibleBarIndex, y2, Color.FromArgb(50, Color.Red.R, Color.Red.G, Color.Red.B));
             ellipse.IsFilled = true;
         }
     }
 }

 import clr
 clr.AddReference("cAlgo.API")
 from cAlgo.API import *
 class Test():
     def initialize(self):
         self.draw()
     def calculate(self, index):
         self.draw()
     def draw(self):
         y1 = api.Bars.HighPrices[api.Chart.FirstVisibleBarIndex] if api.Bars.HighPrices[api.Chart.FirstVisibleBarIndex] > api.Bars.HighPrices[api.Chart.LastVisibleBarIndex] else api.Bars.HighPrices[api.Chart.LastVisibleBarIndex]
         y2 = api.Bars.LowPrices[api.Chart.FirstVisibleBarIndex] if api.Bars.LowPrices[api.Chart.FirstVisibleBarIndex] < api.Bars.LowPrices[api.Chart.LastVisibleBarIndex] else api.Bars.LowPrices[api.Chart.LastVisibleBarIndex]
         ellipse = api.Chart.DrawEllipse("ellipse", api.Chart.FirstVisibleBarIndex, y1, api.Chart.LastVisibleBarIndex, y2, Color.FromArgb(50, Color.Red.R, Color.Red.G, Color.Red.B))
         ellipse.IsFilled = True