private Task<bool> ConstructSamplePolygon(FeatureLayer polygonLayer, FeatureLayer lineLayer) { // execute the fine grained API calls on the CIM main thread return QueuedTask.Run(() => { // get the underlying feature class for each layer var polygonFeatureClass = polygonLayer.GetTable() as FeatureClass; var polygonDefinition = polygonFeatureClass.GetDefinition() as FeatureClassDefinition; var lineFeatureClass = lineLayer.GetTable() as FeatureClass; // construct a cursor to retrieve the line features var lineCursor = lineFeatureClass.Search(null, false); // set up the edit operation for the feature creation var createOperation = new EditOperation() { Name = "Create polygons", SelectNewFeatures = false }; PolylineBuilder polylineBuilder = new PolylineBuilder(polygonDefinition.GetSpatialReference()); while (lineCursor.MoveNext()) { // retrieve the first feature using (var lineFeature = lineCursor.Current as Feature) { // add the coordinate collection of the current geometry into our overall list of collections var polylineGeometry = lineFeature.GetShape() as Polyline; polylineBuilder.AddParts(polylineGeometry.Parts); } } // use the ConvexHull method from the GeometryEngine to construct the polygon geometry var newPolygon = GeometryEngine.Instance.ConvexHull(polylineBuilder.ToGeometry()) as Polygon; // queue the polygon creation createOperation.Create(polygonLayer, newPolygon); // execute the edit (polygon create) operation return createOperation.ExecuteAsync(); }); } protected async override void OnClick() { // to work in the context of the active display retrieve the current map Map activeMap = MapView.Active.Map; // retrieve the first line layer in the map var lineFeatureLayer = activeMap.GetLayersAsFlattenedList().OfType<FeatureLayer>().Where( lyr => lyr.ShapeType == ArcGIS.Core.CIM.esriGeometryType.esriGeometryPolyline).FirstOrDefault(); if (lineFeatureLayer == null) return; // retrieve the first polygon feature layer in the map var polygonFeatureLayer = activeMap.GetLayersAsFlattenedList().OfType<FeatureLayer>().Where( lyr => lyr.ShapeType == ArcGIS.Core.CIM.esriGeometryType.esriGeometryPolygon).FirstOrDefault(); if (polygonFeatureLayer == null) return; //construct the polyline based of the convex hull of all polylines await ConstructSamplePolygon(polygonFeatureLayer, lineFeatureLayer); }