ProSnippets GraphicsLayers

Language:              C#  
Subject:               GraphicsLayers  
Contributor:           ArcGIS Pro SDK Team <arcgisprosdk@esri.com>  
Organization:          esri, http://www.esri.com  
Date:                  10/16/2023  
ArcGIS Pro:            3.2  
Visual Studio:         2022  
.NET Target Framework: .Net 6  

Create GraphicsLayer

var map = MapView.Active.Map;
if (map.MapType != MapType.Map)
  return;// not 2D

var gl_param = new GraphicsLayerCreationParams { Name = "Graphics Layer" };
QueuedTask.Run(() =>
{
  //By default will be added to the top of the TOC
  var graphicsLayer = LayerFactory.Instance.CreateLayer<ArcGIS.Desktop.Mapping.GraphicsLayer>(gl_param, map);

  //Add to the bottom of the TOC
  gl_param.MapMemberIndex = -1; //bottom
  LayerFactory.Instance.CreateLayer<ArcGIS.Desktop.Mapping.GraphicsLayer>(gl_param, map);

  //Add a graphics layer to a group layer...
  var group_layer = map.GetLayersAsFlattenedList().OfType<GroupLayer>().First();
  LayerFactory.Instance.CreateLayer<ArcGIS.Desktop.Mapping.GraphicsLayer>(gl_param, group_layer);

  //TODO...use the graphics layer
  //

  // or use the specific CreateGroupLayer method
  LayerFactory.Instance.CreateGroupLayer(map, -1, "Graphics Layer");
});

Accessing GraphicsLayer

//get the first graphics layer in the map's collection of graphics layers
var graphicsLayer = map.GetLayersAsFlattenedList().OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer != null)
{
  //TODO...use the graphics layer      
}

Copy Graphic elements

//on the QueuedTask
var elems = sourceGraphicsLayer.FindElements(new List<string>() { "Point 1", "Line 3", "Text 1" });
var copiedElements = targetGraphicsLayer.CopyElements(elems);

Remove Graphic elements

//on the QueuedTask      
graphicsLayer.RemoveElements(graphicsLayer.GetSelectedElements());

Create Graphic Elements

Point Graphic Element using CIMGraphic

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
  .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
QueuedTask.Run(() =>
{
  //Place symbol in the center of the map
  var extent = MapView.Active.Extent;
  var location = extent.Center;

  //specify a symbol
  var pt_symbol = SymbolFactory.Instance.ConstructPointSymbol(
                        ColorFactory.Instance.GreenRGB);

  //create a CIMGraphic 
  var graphic = new CIMPointGraphic()
  {
    Symbol = pt_symbol.MakeSymbolReference(),
    Location = location //center of map
  };
  graphicsLayer.AddElement(graphic);
});

Line Graphic Element using CIMGraphic

//On the QueuedTask
//Place a line symbol using the extent's lower left and upper right corner.
var extent = MapView.Active.Extent;
//get the lower left corner of the extent
var pointFromCoordinates = new Coordinate2D(extent.XMin, extent.YMin);
//get the upper right corner of the extent
var pointToCoordinates = new Coordinate2D(extent.XMax, extent.YMax);
List<Coordinate2D> points = new List<Coordinate2D> { pointFromCoordinates, pointToCoordinates };
//create the polyline
var lineSegment = PolylineBuilderEx.CreatePolyline(points);

//specify a symbol
var line_symbol = SymbolFactory.Instance.ConstructLineSymbol(
                      ColorFactory.Instance.GreenRGB);

//create a CIMGraphic 
var graphic = new CIMLineGraphic()
{
  Symbol = line_symbol.MakeSymbolReference(),
  Line = lineSegment,
};
graphicsLayer.AddElement(graphic);

Polygon Graphic Element using CIMGraphic

//On the QueuedTask
//Place a polygon symbol using the mapview extent geometry
var extent = MapView.Active.Extent;
//Contract the extent
var polygonEnv = extent.Expand(-100000, -90000, false);
//create a polygon using the envelope
var polygon = PolygonBuilderEx.CreatePolygon(polygonEnv);

//specify a symbol
var poly_symbol = SymbolFactory.Instance.ConstructPolygonSymbol(
                      ColorFactory.Instance.GreenRGB);

//create a CIMGraphic 
var graphic = new CIMPolygonGraphic()
{
  Symbol = poly_symbol.MakeSymbolReference(),
  Polygon = polygon,
};
graphicsLayer.AddElement(graphic);

Multi-point Graphic Element using CIMGraphic

//On the QueuedTask
//Place a multipoint graphic using the mapview extent geometry
var extent = MapView.Active.Extent;
//Contract the extent
var polygonEnv = extent.Expand(-100000, -90000, false);
//create a polygon using the envelope
var polygon = PolygonBuilderEx.CreatePolygon(polygonEnv);
//Create MultipPoints from the polygon
var multiPoints = MultipointBuilderEx.CreateMultipoint(polygon);
//specify a symbol
var point_symbol = SymbolFactory.Instance.ConstructPointSymbol(
                      ColorFactory.Instance.GreenRGB);

//create a CIMGraphic 
var graphic = new CIMMultipointGraphic
{
  Symbol = point_symbol.MakeSymbolReference(),
  Multipoint = multiPoints
};
graphicsLayer.AddElement(graphic);

Graphic Element using CIMSymbol

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
  .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
QueuedTask.Run(() =>
{
  //Place symbol in the center of the map
  var extent = MapView.Active.Extent;
  var location = extent.Center;

  //specify a symbol
  var pt_symbol = SymbolFactory.Instance.ConstructPointSymbol(
                        ColorFactory.Instance.GreenRGB);        
  graphicsLayer.AddElement(location, pt_symbol);
});

Text Graphic Element

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                    .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
QueuedTask.Run(() =>
{
  //Place symbol in the center of the map
  var extent = MapView.Active.Extent;
  var location = extent.Center;

  //specify a text symbol
  var text_symbol = SymbolFactory.Instance.ConstructTextSymbol
  (ColorFactory.Instance.BlackRGB, 8.5, "Corbel", "Regular");

  graphicsLayer.AddElement(location, text_symbol, "Text Example");
});

Bulk Graphics creation

//Point Feature layer to convert into graphics
var lyr = MapView.Active?.Map?.GetLayersAsFlattenedList().OfType<FeatureLayer>().FirstOrDefault();
//Graphics layer to store the graphics to
var gl = MapView.Active.Map.GetLayersAsFlattenedList().OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (lyr == null) return;
QueuedTask.Run(() =>
{
  //Point symbol for graphics
  var pointSymbol = SymbolFactory.Instance.ConstructPointSymbol(CIMColor.CreateRGBColor(100, 255, 40), 10, SimpleMarkerStyle.Circle);
  //Collection to hold the point graphics
  var listGraphicElements = new List<CIMGraphic>();
  //Iterate through each point feature in the feature layer
  using (RowCursor rows = lyr.Search()) //execute
  {
    int i = 0;
    while (rows.MoveNext())
    {
      using (var feature = rows.Current as Feature)
      {
        //Create a point graphic for the feature
        var crimePt = feature.GetShape() as MapPoint;
        if (crimePt != null)
        {
          var cimGraphicElement = new CIMPointGraphic
          {
            Location = crimePt, //MapPoint
            Symbol = pointSymbol.MakeSymbolReference()
          };
          //Add the point feature to the collection
          listGraphicElements.Add(cimGraphicElement);
          i++;
        }
      }
    }
  }
  //Magic happens...Add all the features to the Graphics layer 
  gl.AddElements(listGraphicElements);
});

Graphic Elements Selection

Select Graphic Elements

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                    .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
var elements = graphicsLayer.GetElementsAsFlattenedList()
                    .Where(e => e.Name.StartsWith("Text"));
QueuedTask.Run(() =>
{
  graphicsLayer.SelectElements(elements);
  //or select one element
  graphicsLayer.SelectElement(elements.FirstOrDefault());
});

Find Graphic elements

//on the QueuedTask
//Find elements by name
var elems = graphicsLayer.FindElements(new List<string>() { "Point 1", "Line 3", "Text 1" });
//Find elements by type
//Find all point graphics in the Graphics Layer
var pointGraphics = graphicsLayer.GetElementsAsFlattenedList().Where(elem => elem.GetGraphic() is CIMPointGraphic);
//Find all line graphics in the Graphics Layer
var lineGraphics = graphicsLayer.GetElementsAsFlattenedList().Where(elem => elem.GetGraphic() is CIMLineGraphic);
//Find all polygon graphics in the Graphics Layer
var polygonGraphics = graphicsLayer.GetElementsAsFlattenedList().Where(elem => elem.GetGraphic() is CIMPolygonGraphic);
//Find all text graphics in the Graphics Layer
var textGraphics = graphicsLayer.GetElementsAsFlattenedList().Where(elem => elem.GetGraphic() is CIMTextGraphic);
//Find all picture graphics in the Graphics Layer
var pictureGraphic = graphicsLayer.GetElementsAsFlattenedList().Where(elem => elem.GetGraphic() is CIMPictureGraphic);

Spatial selection of elements in all Graphics Layers

//Map Tool is used to perform Spatial selection.
//Graphic selection uses the selection geometry 
//to intersect the geometries of those elements (graphic or group) 
//that will be selected and then highlights them. 
protected override async Task<bool> OnSketchCompleteAsync(Geometry geometry)
{
  var selPoly = geometry as Polygon;
  return await QueuedTask.Run(() =>
  {     
    //note: the selected elements may belong to more than one layer...
    var elems = MapView.Active.SelectElements(selPoly, SelectionCombinationMethod.New);
    return true;
  });
}

Spatial selection of elements in one graphics layer

//on the QueuedTask
//Create an extent to use for the spatial selection
var extent = MapView.Active.Extent;
var selectionExtent = extent.Expand(0.5, 0.5, true);
//Select elements in specified graphics layer using the selection extent.
var selectedElements = MapView.Active.SelectElements(graphicsLayer, selectionExtent, SelectionCombinationMethod.Add);

Select Text Graphic Elements

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                    .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
var all_text = graphicsLayer.GetElementsAsFlattenedList()
              .Where(e => e.GetGraphic() is CIMTextGraphic);

Un-Select Graphic elements

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                    .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;
//unselect the first element in the currently selected elements
var elem = graphicsLayer.GetSelectedElements().FirstOrDefault();
QueuedTask.Run( () => {
  if (elem != null)
    //Unselect one element
    graphicsLayer.UnSelectElement(elem);

  //unselect all elements
  graphicsLayer.UnSelectElements();
  //equivalent to
  graphicsLayer.ClearSelection();
});

Graphic Element Events

Subscribe to ElementSelectionChangedEvent

ArcGIS.Desktop.Layouts.Events.ElementEvent.Subscribe((args) => {
  //check if the container is a graphics layer - could be a Layout (or even map view)
  if (args.Container is ArcGIS.Desktop.Mapping.GraphicsLayer graphicsLayer)
  {
    //get the total selection count for the container
    var count = args.Elements.Count();
    //Check count - could have been an unselect or clearselect
    if (count > 0)
    {
      //this is a selection or add to selection
      var elems = graphicsLayer.GetSelectedElements();
      //TODO process the selection...
    }
    else
    {
      //This is an unselect or clear selection
      //TODO process the unselect or clear select
    }
  }
});

Grouping and Ordering Graphic Elements

Group Graphic Elements

var graphicsLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                    .OfType<ArcGIS.Desktop.Mapping.GraphicsLayer>().FirstOrDefault();
if (graphicsLayer == null)
  return;

var elemsToGroup = graphicsLayer.GetSelectedElements();
//Note: run within the QueuedTask
//group  elements
var groupElement = graphicsLayer.GroupElements(elemsToGroup);

Un-Group Graphic Elements

var selectedElements = graphicsLayer.GetSelectedElements().ToList(); ;
if (selectedElements?.Any() == false)//must be at least 1.
  return;
var elementsToUnGroup = new List<GroupElement>();
//All selected elements should be grouped.
if (selectedElements.Count() == selectedElements.OfType<GroupElement>().Count())
{
  //Convert to a GroupElement list.
  elementsToUnGroup = selectedElements.ConvertAll(x => (GroupElement)x);
}
if (elementsToUnGroup.Count() == 0)
  return;
//UnGroup
graphicsLayer.UnGroupElements(elementsToUnGroup);

Parent of GroupElement

//check the parent
var parent = groupElement.Elements.First().GetParent();//will be the group element
//top-most parent
var top_most = groupElement.Elements.First().GetParent(true);//will be the GraphicsLayer

Ordering: Send backward and Bring forward

//On the QueuedTask
//get the current selection set
var sel_elems = graphicsLayer.GetSelectedElements();
//can they be brought forward? This will also check that all elements have the same parent
if (graphicsLayer.CanBringForward(sel_elems))
{
  //bring forward
  graphicsLayer.BringForward(sel_elems);
  //bring to front (of parent)
  //graphicsLayer.BringToFront(sel_elems);
}
else if (graphicsLayer.CanSendBackward(sel_elems))
{
  //send back
  graphicsLayer.SendBackward(sel_elems);
  //send to the back (of parent)
  //graphicsLayer.SendToBack(sel_elems);
}

Get Z-Order

var selElementsZOrder = graphicsLayer.GetSelectedElements();
//list out the z order
foreach (var elem in selElementsZOrder)
  System.Diagnostics.Debug.WriteLine($"{elem.Name}: z-order {elem.ZOrder}");

Modifying Graphic Elements

Move Graphic Elements

//Each selected element will move to a set distance to the upper right.
var selElements = graphicsLayer.GetSelectedElements();
if (selElements.Count == 0) return;
//Move the element up
foreach (var selElement in selElements)
{
  //Get the element's bounds
  var elementPoly = PolygonBuilderEx.CreatePolygon(selElement.GetBounds());
  //get the coordinates of the element bounding envelope.
  var pointsList = elementPoly.Copy2DCoordinatesToList();
  //Move the element's Anchor point to the upper right.
  selElement.SetAnchorPoint(pointsList[1]);
}

Modify symbology of a Graphic Element

//within a queued Task
//get the first line element in the layer
var ge = graphicsLayer.FindElement("Line 10") as GraphicElement;
var graphic = ge.GetGraphic();
if (graphic is CIMLineGraphic lineGraphic)
{
  //change its symbol
  lineGraphic.Symbol =
   SymbolFactory.Instance.ConstructLineSymbol(
     SymbolFactory.Instance.ConstructStroke(
 ColorFactory.Instance.BlueRGB, 2, SimpleLineStyle.DashDot)).MakeSymbolReference();
  //apply the change
  ge.SetGraphic(lineGraphic);
}