public class CIMHatchFill : CIMFill, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

/// <summary>
/// Create a polygon symbol with a diagonal cross hatch fill. <br/>
/// ![PolygonSymbolDiagonalCrossHatch](https://ArcGIS.github.io/arcgis-pro-sdk/images/Symbology/polygon-diagonal-crosshatch.png)
/// </summary>
{
  var trans = 50.0;//semi transparent
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(0, 0, 0, trans), 2.0, SimpleLineStyle.Solid);

  //Stroke for the fill
  var solid = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(255, 0, 0, trans), 1.0, SimpleLineStyle.Solid);

  //Mimic cross hatch
  CIMFill[] diagonalCross =
            {
              new CIMHatchFill() {
                  Enable = true,
                  Rotation = 45.0,
                  Separation = 5.0,
                  LineSymbol = new CIMLineSymbol() { SymbolLayers = new CIMSymbolLayer[1] { solid } }
              },
              new CIMHatchFill() {
                  Enable = true,
                  Rotation = -45.0,
                  Separation = 5.0,
                  LineSymbol = new CIMLineSymbol() { SymbolLayers = new CIMSymbolLayer[1] { solid } }
              }
    };
  List<CIMSymbolLayer> symbolLayers =
    [
      outline, .. diagonalCross
    ];
  //This is the polygon symbol with a diagonal cross hatch fill
  CIMPolygonSymbol diagonalCrossHatchFillSymbol = new()
  {
    SymbolLayers = [.. symbolLayers]
  };
  //To apply the symbol to a polygon feature layer
  //var renderer = theLayer.GetRenderer() as CIMSimpleRenderer;
  //renderer.Symbol = diagonalCrossHatchFillSymbol.MakeSymbolReference();
  //theLayer.SetRenderer(renderer);
}

/// <summary>
/// Create a polygon symbol with a dash dot fill. <br/>
/// ![PolygonSymbolDashDot](https://ArcGIS.github.io/arcgis-pro-sdk/images/Symbology/polygon-dash-dot.png)
/// </summary>
{
  //Note: Run withing QueuedTask
  var trans = 50.0;//semi transparent
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(CIMColor.CreateRGBColor(0, 0, 0, trans), 2.0, SimpleLineStyle.Solid);

  //Stroke for the fill            
  var dashDot = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.RedRGB, 1.0, SimpleLineStyle.DashDotDot);
  //Mimic cross hatch
  CIMFill[] solidColorHatch =
        {

           new CIMHatchFill()
          {
              Enable = true,
              Rotation = 0.0,
              Separation = 2.5,
              LineSymbol = new CIMLineSymbol(){SymbolLayers = new CIMSymbolLayer[1] {dashDot } }
          },
           new CIMSolidFill()
          {
              Enable = true,
              Color = ColorFactory.Instance.CreateRGBColor(255, 255, 0)
          },
};
  List<CIMSymbolLayer> symbolLayers = [outline, .. solidColorHatch];
  //This is the polygon symbol with a dash dot fill
  CIMPolygonSymbol dashDotFillPolygon = new CIMPolygonSymbol() { SymbolLayers = symbolLayers.ToArray() };
  //To apply the symbol to a polygon feature layer
  //var renderer = theLayer.GetRenderer() as CIMSimpleRenderer;
  //renderer.Symbol = dashDotFillPolygon.MakeSymbolReference();
  //theLayer.SetRenderer(renderer);
}