ArcGIS Pro 2.6 API Reference Guide
CreateRectangleGraphicElement Method (IElementFactory)
Example 

ArcGIS.Desktop.Layouts Namespace > IElementFactory Interface : CreateRectangleGraphicElement Method
Layout or GroupElement
Envelope
CIMPolygonSymbol
Creates a graphic rectangle element on a layout from a single envelope geometry. This method must be called on the MCT. Use QueuedTask.Run.
Syntax

Parameters

elementContainer
Layout or GroupElement
envelope
Envelope
polygonSymbol
CIMPolygonSymbol

Return Value

Returns a GraphicElement.
Exceptions
ExceptionDescription
This method or property must be called within the lambda passed to QueuedTask.Run.
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 rectangle graphic and apply simple fill and outline symbols.

//Construct on the worker thread
await QueuedTask.Run(() =>
{
  //Build 2D envelope geometry
  Coordinate2D rec_ll = new Coordinate2D(1.0, 4.75);
  Coordinate2D rec_ur = new Coordinate2D(3.0, 5.75);
  Envelope rec_env = EnvelopeBuilder.CreateEnvelope(rec_ll, rec_ur);

  //Set symbolology, create and add element to layout
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.BlackRGB, 5.0, SimpleLineStyle.Solid);
  CIMPolygonSymbol polySym = SymbolFactory.Instance.ConstructPolygonSymbol(ColorFactory.Instance.GreenRGB, SimpleFillStyle.DiagonalCross, outline);
  GraphicElement recElm = LayoutElementFactory.Instance.CreateRectangleGraphicElement(layout, rec_env, polySym);
  recElm.SetName("New Rectangle");
});
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

IElementFactory Interface
IElementFactory Members