System.Object
   Xamarin.Forms.BindableObject
      Xamarin.Forms.Element
         Xamarin.Forms.VisualElement
            Xamarin.Forms.View
               C1.Xamarin.Forms.Chart.Annotation.AnnotationBase
                  C1.Xamarin.Forms.Chart.Annotation.Image
                  C1.Xamarin.Forms.Chart.Annotation.Shape
                     C1.Xamarin.Forms.Chart.Annotation.Circle
                     C1.Xamarin.Forms.Chart.Annotation.Ellipse
                     C1.Xamarin.Forms.Chart.Annotation.Line
                     C1.Xamarin.Forms.Chart.Annotation.Polygon
                     C1.Xamarin.Forms.Chart.Annotation.Rectangle
                     C1.Xamarin.Forms.Chart.Annotation.Square
                  C1.Xamarin.Forms.Chart.Annotation.Template
                  C1.Xamarin.Forms.Chart.Annotation.Text
               C1.Xamarin.Forms.Chart.Annotation.AnnotationLayer

Reference

C1.Xamarin.Forms.Chart Assembly