//Must be on QueuedTask.Run(() => { ...
//Build geometry
Coordinate2D center = new Coordinate2D(2, 2.75);
var eabElp = new EllipticArcBuilderEx(
center, 0, 1, 0.45, ArcOrientation.ArcClockwise);
var ellipse = eabElp.ToSegment();
//Set symbology, create and add element to layout
CIMStroke outline = SymbolFactory.Instance.ConstructStroke(
ColorFactory.Instance.GreenRGB, 2.0, SimpleLineStyle.Dot);
CIMPolygonSymbol ellipseSym = SymbolFactory.Instance.ConstructPolygonSymbol(
ColorFactory.Instance.GreyRGB, SimpleFillStyle.Vertical, outline);
var poly = PolygonBuilderEx.CreatePolygon(
PolylineBuilderEx.CreatePolyline(ellipse, AttributeFlags.AllAttributes));
var ge = ElementFactory.Instance.CreatePredefinedShapeGraphicElement(
container, PredefinedShape.Ellipse, poly.Extent.Center, 0, 0, ellipseSym,
"New Ellipse2", false, new ElementInfo() { Anchor = Anchor.TopRightCorner });