public override Envelope Extent {get;}

// clip a polyline by a polygon

List<Coordinate2D> list = new List<Coordinate2D>();
list.Add(new Coordinate2D(1.0, 1.0));
list.Add(new Coordinate2D(1.0, 4.0));
list.Add(new Coordinate2D(4.0, 4.0));
list.Add(new Coordinate2D(4.0, 1.0));

Polygon polygon = PolygonBuilderEx.CreatePolygon(list, SpatialReferences.WGS84);

LineSegment crossingLine = LineBuilderEx.CreateLineSegment(MapPointBuilderEx.CreateMapPoint(0, 3), MapPointBuilderEx.CreateMapPoint(5.0, 3.0));
Polyline p = PolylineBuilderEx.CreatePolyline(crossingLine);
Geometry geometry = GeometryEngine.Instance.Clip(p, polygon.Extent);