public abstract class CIMSymbolLayer : CIMObject, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

//These methods must be called within the lambda passed to QueuedTask.Run
var lineStrokeRed = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.RedRGB, 4.0);
var markerCircle = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.RedRGB, 12, SimpleMarkerStyle.Circle);
markerCircle.MarkerPlacement = new CIMMarkerPlacementOnVertices()
{
  AngleToLine = true,
  PlaceOnEndPoints = true,
  Offset = 0
};
var lineSymbolWithCircles = new CIMLineSymbol()
{
  SymbolLayers = new CIMSymbolLayer[2] { markerCircle, lineStrokeRed }
};

//These methods must be called within the lambda passed to QueuedTask.Run
var markerTriangle = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.RedRGB, 12, SimpleMarkerStyle.Triangle);
markerTriangle.Rotation = -90; // or -90
markerTriangle.MarkerPlacement = new CIMMarkerPlacementOnLine() { AngleToLine = true, RelativeTo = PlacementOnLineRelativeTo.LineEnd };

var lineSymbolWithArrow = new CIMLineSymbol()
{
  SymbolLayers = new CIMSymbolLayer[2] { markerTriangle,
              SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.RedRGB, 2)
          }
};

/// <summary>
/// Creates Mesh procedural symbol with various textures.
/// ![MeshProceduralTexture](http://Esri.github.io/arcgis-pro-sdk/images/Symbology/mesh-procedural-texture.png)
/// </summary>
/// <remarks>Note: The rule package used in this method can be obtained from the Sample Data included in the arcgis-pro-sdk-community-samples repository.</remarks>
/// <returns></returns>
private static readonly string _rulePkgPath = @"C:\Data\RulePackages\MultipatchTextures.rpk";
public static Task<CIMMeshSymbol> CreateProceduralMeshSymbolAsync()
{
    return QueuedTask.Run<CIMMeshSymbol>(() =>
    {                  
        CIMSymbolLayer[] proceduralSymbolLyr =
        {
            new CIMProceduralSymbolLayer()
            {
                PrimitiveName = "Textures",
                RulePackage = _rulePkgPath,
                RulePackageName = "Textures",
            }
        };
        var myMeshSymbol = new CIMMeshSymbol()
        {
            SymbolLayers = proceduralSymbolLyr
        };

        return myMeshSymbol;
    });
}

/// <summary>
/// Create a polygon symbol using the ConstructHatchFill method . <br/>
/// ![PolygonSymbolDiagonalCrossHatch](http://Esri.github.io/arcgis-pro-sdk/images/Symbology/ConstructHatchFill.png)
/// </summary>
/// <returns></returns>
private static Task<CIMPolygonSymbol> CreateHatchFillPolygonAsync()
{
  return QueuedTask.Run<CIMPolygonSymbol>(() =>
  {
    CIMStroke lineStroke = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(51, 51, 51, 60), 4, SimpleLineStyle.Solid);
    //gradient
    var hatchFill = SymbolFactory.Instance.ConstructHatchFill(lineStroke, 45, 6, 0);

    List<CIMSymbolLayer> symbolLayers = new List<CIMSymbolLayer>
    {
      hatchFill
    };
    return new CIMPolygonSymbol() { SymbolLayers = symbolLayers.ToArray() };
  });
}

/// <summary>
/// Create a polygon symbol with a gradient color fill. <br/>
/// ![PolygonSymbolGradientColor](http://Esri.github.io/arcgis-pro-sdk/images/Symbology/polygon-gradient-color.png)
/// </summary>
/// <remarks>
/// 1. Create a solid colored stroke with 50% transparency
/// 1. Create a fill using gradient colors red through green
/// 1. Apply both the stroke and fill as a symbol layer array to the new PolygonSymbol
/// </remarks>
/// <returns></returns>
public static Task<CIMPolygonSymbol> CreateGradientFillAsync()
{
  return QueuedTask.Run<CIMPolygonSymbol>(() =>
  {
    var trans = 50.0;//semi transparent
    CIMStroke outline = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(0, 0, 0, trans), 2.0, SimpleLineStyle.Solid);
    //Mimic cross hatch
    CIMFill solidColorHatch =
           new CIMGradientFill()
       {
         ColorRamp = ColorFactory.Instance.ConstructColorRamp(ColorRampAlgorithm.LinearContinuous,
                                  ColorFactory.Instance.RedRGB, ColorFactory.Instance.GreenRGB)
       };
    List<CIMSymbolLayer> symbolLayers = new List<CIMSymbolLayer>
      {
                outline,
                solidColorHatch
      };

    return new CIMPolygonSymbol() { SymbolLayers = symbolLayers.ToArray() };
  });
}