public class CIMLineSymbol : CIMMultiLayerSymbol, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

{
  //Note: Must be on QueuedTask.Run
  //Build geometry
  List<Coordinate2D> plCoords = new List<Coordinate2D>();
  plCoords.Add(new Coordinate2D(1.5, 10.5));
  plCoords.Add(new Coordinate2D(1.25, 9.5));
  plCoords.Add(new Coordinate2D(1, 10.5));
  plCoords.Add(new Coordinate2D(0.75, 9.5));
  plCoords.Add(new Coordinate2D(0.5, 10.5));
  plCoords.Add(new Coordinate2D(0.5, 1));
  plCoords.Add(new Coordinate2D(0.75, 2));
  plCoords.Add(new Coordinate2D(1, 1));
  Polyline linePl = PolylineBuilderEx.CreatePolyline(plCoords);

  //Set symbology, create and add element to layout
  CIMLineSymbol lineSym = SymbolFactory.Instance.ConstructLineSymbol(
            ColorFactory.Instance.BlackRGB, 2.0, SimpleLineStyle.Solid);
  //var graphic = GraphicFactory.Instance.CreateShapeGraphic(linePl, lineSym);

  var ge = ElementFactory.Instance.CreateGraphicElement(
                          layout, linePl, lineSym, "New Freehand");
}

{
  //Create a simple 2D line graphic and apply an existing line
  //style item as the symbology.
  //Note: Must be on 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 = PolylineBuilderEx.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 symbology, create and add element to layout

  //An alternative simple symbol is also commented out below.
  //This would eliminate the four optional lines of code above that
  //reference a style.
  //
  //CIMLineSymbol lineSym = SymbolFactory.Instance.ConstructLineSymbol(
  //         ColorFactory.Instance.BlueRGB, 4.0, SimpleLineStyle.Solid);  


  GraphicElement lineElm = ElementFactory.Instance.CreateGraphicElement(
                                              layout, linePl, lineSym);
  lineElm.SetName("New Line");
}

{
    CIMLineSymbol lineSymbol = SymbolFactory.Instance.ConstructLineSymbol(ColorFactory.Instance.BlueRGB, 4.0, SimpleLineStyle.Solid);
}

{
    CIMStroke stroke = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.BlackRGB, 2.0);
    CIMLineSymbol lineSymbolFromStroke = SymbolFactory.Instance.ConstructLineSymbol(stroke);
}

{
    //Note: Needs QueuedTask to 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 }
    };
}

{
      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>
/// Create a line symbol with the markers placed at a 45 degree angle. <br/>  
/// ![LineSymbolAngleMarker](https://ArcGIS.github.io/arcgis-pro-sdk/images/Symbology/line-marker-angle.png)
/// </summary>
{
  //Create a line symbol with the markers placed at a 45 degree angle.
  //Create a marker from the "|" character.  This is the marker that will be used to render the line layer.
  //Note: Run withing QueuedTask
  var lineMarker = SymbolFactory.Instance.ConstructMarker(124, "Agency FB", "Regular", 12);

  //Default line symbol which will be modified 
  CIMLineSymbol lineSymbolWithMarkersAtAngle = SymbolFactory.Instance.ConstructLineSymbol(ColorFactory.Instance.BlackRGB, 2, SimpleLineStyle.Solid);

  //Modifying the marker to align with line
  //First define "markerplacement"
  CIMMarkerPlacementAlongLineSameSize markerPlacement = new CIMMarkerPlacementAlongLineSameSize()
  {
    AngleToLine = true,
    PlacementTemplate = new double[] { 5 }
  };
  //assign the markerplacement to the marker
  lineMarker.MarkerPlacement = markerPlacement;
  //angle the marker if needed
  lineMarker.Rotation = 45;

  //assign the marker as a layer to the line symbol
  lineSymbolWithMarkersAtAngle.SymbolLayers[0] = lineMarker;
}

/// <summary>
/// Create a line symbol with a dash and two markers.<br/>          
/// This line symbol comprises three symbol layers listed below: 
/// 1. A solid stroke that has dashes.
/// 1. A circle marker.
/// 1. A square marker.
/// ![LineSymbolTwoMarkers](https://ArcGIS.github.io/arcgis-pro-sdk/images/Symbology/line-dash-two-markers.png)
/// </summary>
{
  //Create a line symbol with a dash and two markers.
  //Note: Run withing QueuedTask
  CIMLineSymbol dash2MarkersLine = new CIMLineSymbol();
  var mySymbolLyrs = new CIMSymbolLayer[]
        {
              new CIMSolidStroke()
              {
                  Color = ColorFactory.Instance.BlackRGB,
                  Enable = true,
                  ColorLocked = true,
                  CapStyle = LineCapStyle.Round,
                  JoinStyle = LineJoinStyle.Round,
                  LineStyle3D = Simple3DLineStyle.Strip,
                  MiterLimit = 10,
                  Width = 1,
                  CloseCaps3D = false,
                  Effects = new CIMGeometricEffect[]
                  {
                      new CIMGeometricEffectDashes()
                      {
                          CustomEndingOffset = 0,
                          DashTemplate = new double[] {20, 10, 20, 10},
                          LineDashEnding = LineDashEnding.HalfPattern,
                          OffsetAlongLine = 0,
                          ControlPointEnding = LineDashEnding.NoConstraint
                      },
                      new CIMGeometricEffectOffset()
                      {
                          Method = GeometricEffectOffsetMethod.Bevelled,
                          Offset = 0,
                          Option = GeometricEffectOffsetOption.Fast
                      }
                  },
              },
              CreateCircleMarkerPerSpecs(),
              CreateSquareMarkerPerSpecs()
    };
  dash2MarkersLine.SymbolLayers = mySymbolLyrs;

  static CIMMarker CreateCircleMarkerPerSpecs()
  {
    var circleMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.BlackRGB, 5, SimpleMarkerStyle.Circle) as CIMVectorMarker;
    //Modifying the marker to align with line
    //First define "markerplacement"
    CIMMarkerPlacementAlongLineSameSize markerPlacement = new CIMMarkerPlacementAlongLineSameSize()
    {
      AngleToLine = true,
      Offset = 0,
      Endings = PlacementEndings.Custom,
      OffsetAlongLine = 15,
      PlacementTemplate = new double[] { 60 }
    };
    //assign the markerplacement to the marker
    circleMarker.MarkerPlacement = markerPlacement;
    return circleMarker;
  }
  static CIMMarker CreateSquareMarkerPerSpecs()
  {
    var squareMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.BlueRGB, 5, SimpleMarkerStyle.Square) as CIMVectorMarker;
    CIMMarkerPlacementAlongLineSameSize markerPlacement2 = new CIMMarkerPlacementAlongLineSameSize()
    {
      AngleToLine = true,
      Endings = PlacementEndings.Custom,
      OffsetAlongLine = 45,
      PlacementTemplate = new double[] { 60 },
    };
    squareMarker.MarkerPlacement = markerPlacement2;
    return squareMarker;
  }
}

/// <summary>
/// Create a line symbol with a dash and two markers. <br/>
/// In this pattern of creating this symbol, a [CIMVectorMarker](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic6176.html) object is created as a new [CIMSymbolLayer](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic5503.html).
/// The circle and square markers created by [ContructMarker](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic12350.html) method is then assigned to the [MarkerGraphics](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic6188.html) property of the CIMVectorMarker. 
/// When using this method, the CIMVectorMarker's [Frame](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic6187.html) property needs to be set to the [CIMMarker](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic3264.html) object's Frame. 
/// Similarly, the CIMVectorMarker's [Size](https://pro.arcgis.com/en/pro-app/sdk/api-reference/#topic3284.html) property needs to be set to the CIMMarker object's size.
/// This line symbol comprises three symbol layers listed below: 
/// 1. A solid stroke that has dashes.
/// 1. A circle marker.
/// 1. A square marker.
/// ![LineSymbolTwoMarkers](https://ArcGIS.github.io/arcgis-pro-sdk/images/Symbology/line-dash-two-markers.png)
/// </summary>
{
  // Create a line symbol with a dash and two markers.
  //default line symbol that will get modified.
  //Note: Run withing QueuedTask
  CIMLineSymbol dash2MarkersLine = new CIMLineSymbol();
  //circle marker to be used in our line symbol as a layer
  var circleMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.BlackRGB, 5, SimpleMarkerStyle.Circle) as CIMVectorMarker;
  //circle marker to be used in our line symbol as a layer
  var squareMarker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.BlueRGB, 5, SimpleMarkerStyle.Square) as CIMVectorMarker;
  //Create the array of layers that make the new line symbol
  CIMSymbolLayer[] mySymbolLyrs =
      {
              new CIMSolidStroke() //dash line
              {
                  Color = ColorFactory.Instance.BlackRGB,
                  Enable = true,
                  ColorLocked = true,
                  CapStyle = LineCapStyle.Round,
                  JoinStyle = LineJoinStyle.Round,
                  LineStyle3D = Simple3DLineStyle.Strip,
                  MiterLimit = 10,
                  Width = 1,
                  CloseCaps3D = false,
                  Effects = new CIMGeometricEffect[]
                  {
                      new CIMGeometricEffectDashes()
                      {
                          CustomEndingOffset = 0,
                          DashTemplate = new double[] {20, 10, 20, 10},
                          LineDashEnding = LineDashEnding.HalfPattern,
                          OffsetAlongLine = 0,
                          ControlPointEnding = LineDashEnding.NoConstraint
                      },
                      new CIMGeometricEffectOffset()
                      {
                          Method = GeometricEffectOffsetMethod.Bevelled,
                          Offset = 0,
                          Option = GeometricEffectOffsetOption.Fast
                      }
                  }
              },
              new CIMVectorMarker() //circle marker
              {
                  MarkerGraphics = circleMarker.MarkerGraphics,
                  Frame = circleMarker.Frame, //need to match the CIMVector marker's frame to the circleMarker's frame.
                  Size = circleMarker.Size,    //need to match the CIMVector marker's size to the circleMarker's size.                    
                 MarkerPlacement = new CIMMarkerPlacementAlongLineSameSize()
                 {
                     AngleToLine = true,
                     Offset = 0,
                     Endings = PlacementEndings.Custom,
                     OffsetAlongLine = 15,
                     PlacementTemplate = new double[] {60},
                 }

              },
              new CIMVectorMarker() //square marker
              {
                 MarkerGraphics = squareMarker.MarkerGraphics,
                 Frame = squareMarker.Frame, //need to match the CIMVector marker's frame to the squareMarker frame.
                 Size = squareMarker.Size, //need to match the CIMVector marker's size to the squareMarker size.
                 MarkerPlacement = new CIMMarkerPlacementAlongLineSameSize()
                 {
                     AngleToLine = true,
                     Endings = PlacementEndings.Custom,
                     OffsetAlongLine = 45,
                     PlacementTemplate = new double[] {60},
                 }
              }
    };
  dash2MarkersLine.SymbolLayers = mySymbolLyrs;
}

/// <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);
}