ArcGIS Pro 2.6 API Reference Guide
CreateLineGraphicElement Method (LayoutElementFactory)
Example 

ArcGIS.Desktop.Layouts Namespace > LayoutElementFactory Class : CreateLineGraphicElement Method
Layout or GroupElement
Polyline
CIMLineSymbol
Creates a graphic line element on a layout from a single polyline geometry. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
Public Function CreateLineGraphicElement( _
   ByVal elementContainer As ILayoutElementContainer, _
   ByVal polyline As Polyline, _
   Optional ByVal lineSymbol As CIMLineSymbol _
) As GraphicElement

Parameters

elementContainer
Layout or GroupElement
polyline
Polyline
lineSymbol
CIMLineSymbol

Return Value

Returns a GraphicElement.
Exceptions
ExceptionDescription
This method or property must be called within the lambda passed to QueuedTask.Run.
Map has reached maximum graphics count limit of 4000 elements. One or more elements cannot be created.
Map has reached maximum graphics size limit of 10 MB. One or more elements cannot be created.
Remarks
If the element container is a Layout then the element gets added to the root level of the layout TOC at the top most position. If the element container is a GroupElement then it gets added to the group at the topmost position.
Example
//Create a simple 2D line graphic and apply an existing line style item as the symbology.

//Construct on the worker thread
await QueuedTask.Run(() =>
{
  //Build 2d line geometry
  List<Coordinate2D> plCoords = new List<Coordinate2D>();
  plCoords.Add(new Coordinate2D(1, 8.5));
  plCoords.Add(new Coordinate2D(1.66, 9));
  plCoords.Add(new Coordinate2D(2.33, 8.1));
  plCoords.Add(new Coordinate2D(3, 8.5));
  Polyline linePl = PolylineBuilder.CreatePolyline(plCoords);

  //(optionally) Reference a line symbol in a style
  StyleProjectItem lnStylePrjItm = Project.Current.GetItems<StyleProjectItem>().FirstOrDefault(item => item.Name == "ArcGIS 2D");
  SymbolStyleItem lnSymStyleItm = lnStylePrjItm.SearchSymbols(StyleItemType.LineSymbol, "Line with 2 Markers")[0];
  CIMLineSymbol lineSym = lnSymStyleItm.Symbol as CIMLineSymbol;
  lineSym.SetSize(20);

  //Set symbolology, create and add element to layout

  //An alternative simple symbol is also commented out below.  This would elminate the four 
  //optional lines of code above that reference a style.

  //CIMLineSymbol lineSym = SymbolFactory.Instance.ConstructLineSymbol(ColorFactory.Instance.BlueRGB, 4.0, SimpleLineStyle.Solid);  //Alternative simple symbol
  GraphicElement lineElm = LayoutElementFactory.Instance.CreateLineGraphicElement(layout, linePl, lineSym);
  lineElm.SetName("New Line");
});
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

LayoutElementFactory Class
LayoutElementFactory Members