topic Re: How to programatically create a line symbol with a Arrow at the endpoint. in ArcGIS Pro SDK Questions

How to programatically create a line symbol with a Arrow at the endpoint.

StephenCochrane — Wed, 21 Sep 2022 10:01:47 GMT

I am trying to programmatically construct a simple line symbol using ArcGIS pro sdk for .net. It should show the features with an arrow at the end node of each feature (and only at the end node). I am not sure if need to use line symbol with marker symbols (it seems a bit complicated for a relative simple symbol).

I the old ArcMap application I am migrating i had this code for the symbol

private static CartographicLineSymbolClass CreateArrowSymbol(Color c) { var color = new RgbColorClass() { Red = c.R, Green = c.G, Blue = c.B }; var de = new SimpleLineDecorationElementClass(); de.AddPosition(1); de.MarkerSymbol = new ArrowMarkerSymbolClass() { Color = color, Size = 8.0, Length = 6.0 }; var ld = new LineDecorationClass(); ld.AddElement(de); var symbol = new CartographicLineSymbolClass() { Color = color, Width = 1.5, LineDecoration = ld }; return symbol; }

Re: How to programatically create a line symbol with a Arrow at the endpoint.

CharlesMacleod — Wed, 21 Sep 2022 15:16:29 GMT

Stephen, i cover symbology in quite some depth here: ArcGIS Pro SDK for .NET: An Introduction to the Use of the CIM with Symbology in Pro (from Dev summit 2021) and, specifically, arrow heads: 48:30 ish

ppt and code is here: https://esri.github.io/arcgis-pro-sdk/techsessions/2021/PalmSprings/CIMSymbology.zip

You will need to use something called a CIMMarkerPlacementAtExtremities and apply that to your arrow marker. Along these lines (no pun intended):

var symbol_layers = new List<CIMSymbolLayer>(); var stroke = SymbolFactory.Instance.ConstructStroke( ColorFactory.Instance.BlackRGB, 2.0); //End arrow var arrow = SymbolFactory.Instance.ConstructMarker( 63, "ESRI Arrowhead", "Regular", 10) as CIMCharacterMarker; //Marker placement on end - Both, JustBegin, JustEnd var endMarkerPlacement = new CIMMarkerPlacementAtExtremities() { ExtremityPlacement = ExtremityPlacement.JustEnd, PlacePerPart = false, AngleToLine = true }; arrow.MarkerPlacement = endMarkerPlacement; //reverse Z-order symbol_layers.Add(arrow); symbol_layers.Add(stroke); var CIMLineSymbol = new CIMLineSymbol() { SymbolLayers = layers.ToArray() };

Re: How to programatically create a line symbol with a Arrow at the endpoint.

Wolf — Wed, 21 Sep 2022 21:11:52 GMT

Stephen, you can also use a pre-defined arrow symbol using this code:

if (_lineSymbol == null) { //Get all styles in the project var styleProjectItem2D = Project.Current.GetItems<StyleProjectItem>().FirstOrDefault(s => s.Name == "ArcGIS 2D"); await QueuedTask.Run(() => { //Get a specific project style by name var arrowLineSymbol = styleProjectItem2D.SearchSymbols(StyleItemType.LineSymbol, "Arrow Line 2 (Mid)")[0]; if (arrowLineSymbol == null) return; _lineSymbol = arrowLineSymbol.Symbol; }); }

The example symbology will look like this:

I attached a sample tool code snippet that shows the symbology using a graphic overlay.

EDIT: please substitute the SearchSymbol string using the following to get an arrow at the end:

styleProjectItem2D.SearchSymbols(StyleItemType.LineSymbol, "Bold Arrow 2")[0];

Re: How to programatically create a line symbol with a Arrow at the endpoint.

StephenCochrane — Sun, 02 Oct 2022 20:05:37 GMT

Hi Charles

Thanks a lot. The links were very use full for my project in general. In regard to your solution, it was working but I could not change the color of the marker (arrowhead).

I think it should be rather simple but setting the color in line 8 below does not seem to work. It got what I wanted using Wolf solution below so this it just my curiosity

private static CIMLineSymbol CreateArrowLineSymbol(System.Drawing.Color color) { var cimColor = ColorFactory.Instance.CreateColor(color); var symbol_layers = new List<CIMSymbolLayer>(); var stroke = SymbolFactory.Instance.ConstructStroke(cimColor, 2.0); //End arrow var arrow = SymbolFactory.Instance.ConstructMarker(63, "ESRI Arrowhead", "Regular", 10, cimColor) as CIMCharacterMarker; //Marker placement on end - Both, JustBegin, JustEnd var endMarkerPlacement = new CIMMarkerPlacementAtExtremities() { ExtremityPlacement = ExtremityPlacement.JustEnd, PlacePerPart = false, AngleToLine = true, }; arrow.MarkerPlacement = endMarkerPlacement; //reverse Z-order symbol_layers.Add(arrow); symbol_layers.Add(stroke); var CIMLineSymbol = new CIMLineSymbol() { SymbolLayers = symbol_layers.ToArray() }; return CIMLineSymbol; }

Re: How to programatically create a line symbol with a Arrow at the endpoint.

StephenCochrane — Sun, 02 Oct 2022 20:08:49 GMT

Thanks a lot, Wolf.

It worked super.