Latest Contributions by ThadTilton

The good news: Features and graphics in your ArcGIS Runtime SDK for .NET app can be labeled using a combination of attribute values, text strings, and values calculated with an expression. You can set font characteristics, determine how labels are positioned and prioritized, and how conflicts between overlapping labels are automatically and dynamically resolved. By creating one or more label classes, you can define distinct labels for groups of features. The bad news: As of the 100.2.1 release, there's no API exposed for this. To implement labeling for a feature layer, graphics overlay, or map image sub-layer, you need to craft the appropriate JSON definition (text) to define your label classes (as described here). Bummer. But don't worry, a simple JSON serializable class is all it takes to simplify your labeling code. I'll walk you through the basic process in the steps below. If that's still too much work for you, feel free to simply download the attached code and try it out. The labeling class in the project (LabelClassInfo.cs) can be brought into any ArcGIS Runtime for .NET project and used to create labels for your layers. Start Visual Studio and create a new ArcGIS Runtime SDK for .NET app.  Add a new class to the project. Let's name it LabelClassInfo.cs. Add the following using statements at the top of the class. using Esri.ArcGISRuntime.Geometry; using Esri.ArcGISRuntime.Symbology; using System; using System.IO; using System.Runtime.Serialization; using System.Runtime.Serialization.Json;‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Decorate the class with the DataContract attribute. This indicates that the class will be serializable.      [DataContract]     public class LabelClassInfo     {‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Create properties for everything expected in the JSON definition of the label class. This information is defined under labelingInfo in the Web map specification. The specification defines an "allowOverrun" value, for example. This could be implemented with the following simple bool property. Note that the name of the property in the class does not need to match the name in the specification.         public bool AllowOverrun { get; set; }‍‍‍‍‍‍ Based on the specification, here are the properties (and corresponding data type) needed for the label class: allowOverrun (bool), deconflictionStrategy (string), labelExpression (string), labelExpressionInfo (object), labelPlacement (string), minScale (int), maxScale (int), name (string), priority (int), removeDuplicates (string), removeDuplicatesDistance (int), repeatLabel (bool), repeatLabelDistance (int), stackLabel (bool), stackAlignment (string), symbol (TextSymbol), useCodedValues (bool), where (string). OK, the list above looks pretty straightforward, except for the two properties that don't return primitive data types. Go ahead and create properties for everything except labelExpressionInfo and symbol (we'll circle back to those).  After you've defined the properties, in order to make them serializable you'll need to decorate them with the DataMember attribute. The string you supply for "Name" will be used in the output JSON and must match the name used in the Web map specification. Add the appropriate DataMember attribute to all properties.         [DataMember(Name = "deconflictionStrategy")]         public LabelPosition LabelPosition { get; set; }‍‍‍‍‍‍‍‍ The labelExpressionInfo property, returns object. What kind of object do we need here? In the specification, the JSON describes a class with a single property (not counting the deprecated "value" property). You'll therefore need to create a new private class (nested under your main class) with a single property that holds a (string) expression. This class will also be serializable, so you need the DataContract and DataMember attributes.          [DataContract]         private class ExpressionInfo         {             [DataMember(Name = "expression")]             public string Expression { get; set; }             public ExpressionInfo(string expression)             {                 Expression = expression;             }         }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ The labelExpressionInfo property should be based on the new ExpressionInfo type. To simplify the API, you might want to expose just the expression property (ArcadeExpression in the example below) and build the ExpressionInfo object that contains it internally.          [DataMember(Name ="labelExpressionInfo")]         private ExpressionInfo _labelExpressionInfo = new ExpressionInfo("");         public string ArcadeExpression         {             get { return _labelExpressionInfo.Expression; }             set { _labelExpressionInfo = new ExpressionInfo(value); }         }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ What about the symbol property that returns TextSymbol? You can handle this is much the same way: expose a public Symbol property of type TextSymbol, then use an internal property to get its JSON representation (yes, Esri.ArcGISRuntime.Symbology.Symbol is serializable!).         public TextSymbol Symbol { get; set; }         [DataMember(Name = "symbol")]         private string SymbolString         {             get { return this.Symbol.ToJson(); }             set { this.Symbol = (TextSymbol)TextSymbol.FromJson(value); }         }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Finally, create a method on LabelClassInfo to return the JSON representation of the object.         public string GetJson()         {             // Create a JSON serializer for the label class.             DataContractJsonSerializer jsonSerializer = new DataContractJsonSerializer(typeof(LabelClassInfo));             // Write the object to a memory stream.             MemoryStream stream = new MemoryStream();             jsonSerializer.WriteObject(stream, this);             // Read the stream to a string.             stream.Position = 0;             StreamReader reader = new StreamReader(stream);             string json = reader.ReadToEnd();             // HACK: clean up the json a bit.             json = json.Replace("\"{", "{").Replace("}\"", "}").Replace("\\", "\"").Replace("\"\"", "\"");             // Return the serialized string.             return json;         }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ You should now be able to use the new LabelClassInfo class to write code like the following to apply labels to a feature layer!             TextSymbol textSymbol = new TextSymbol             {                 FontFamily = "Arial",                 FontWeight = weight,                 Size = (int)TextSizeComboBox.SelectedValue,                 HorizontalAlignment = Esri.ArcGISRuntime.Symbology.HorizontalAlignment.Left,                 VerticalAlignment = Esri.ArcGISRuntime.Symbology.VerticalAlignment.Bottom,                 Color = (Color)ColorComboBox.SelectedValue             };             // Create a new LabelInfo object and set the relevant properties (including the text symbol).             LabelClassInfo labelInfo = new LabelClassInfo()             {                 LabelPosition = "static",                 ArcadeExpression = "return $feature['" + LabelFieldComboBox.SelectedItem + "'];",                 MinScale = 0,                 MaxScale = 0,                 Priority = 30,                 RemoveDuplicateLabels = "featureType",                 StackLabel = true,                 Symbol = textSymbol             };             // Get the raw JSON from the label info object.             labelJson = labelInfo.GetJson();             // Create a new label definition from the JSON string.             LabelDefinition labelDef = LabelDefinition.FromJson(labelJson);             // Clear existing label definitions.             _parcelsLayer.LabelDefinitions.Clear();             // Add the new label definition.             _parcelsLayer.LabelDefinitions.Add(labelDef);‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ OK, so it might not be the easiest thing to code, but once you have it you can reuse this class anytime you need to add labels for a layer. Apologies if the steps above were too vague or if you got stuck because I left something out! I've attached a project with the LabelClassInfo class and a WPF app for testing. The attached example also includes some enums for defining label position, placement, and handling of stacking and duplicates. Update (2018 March 13): I've attached a much cleaner version of the LabelClassInfo class ("LabelClassInfo2.cs") that uses Newtonsoft.Json (thanks to Matvei Stefarov on the ArcGIS Runtime SDK for .NET team). Including a link to a a utility that helps create your serializable class from JSON: Instantly parse JSON in any language | quicktype  ... View more

If you've ever had to show the density of point features on a map, you may already be familiar with the concept of a heat map, which allows you to generalize the display of points according to their density. A heat map provides an excellent tool for discovering patterns in your data. In addition to looking at density of point location, you can also provide a field in your dataset with which to weight the density. This allows you to look at the density of things like sales (dollars, for example) instead of just the density of customers over an area. Heat maps are displayed with a color ramp that usually shows dense areas with a darker color (red, for example) and sparse areas with a light color (such as yellow). You may have used a heat map renderer to display your point data in the ArcGIS Online map viewer or ArcGIS Pro. The heat map below shows the density of earthquakes weighted with a field that contains the magnitude. "Sounds great". You might be saying. "I'm excited to try it in my ArcGIS Runtime for .NET app"! "Um, yeah. About that." I would say, sheepishly looking at my shoes. While there is support in ArcGIS Runtime for reading things like a heat map renderer from a web map, there's no API exposed (as of v100.2.1) that allows you to construct one and apply it to a point layer without crafting the raw JSON definition. Fortunately, with a little effort, there's a way to make it much easier to work with. In a previous blog, I described how to create a serializable class to define labeling properties to apply to a layer. I'll describe the same technique here to define a heat map renderer class that can be serialized to JSON and applied to your point layer. If you don't really care about the details and just want to start using it, you can download the completed class and sample project and give it a try. Start Visual Studio and create a new ArcGIS Runtime SDK for .NET app.  Use the NuGet Package Manager to add the Newtonsoft.Json package to the project. Add a new class to the project. Let's name it HeatMapRenderer.cs. Add the following using statements at the top of the class. using Newtonsoft.Json; using System; using System.Collections.Generic; using System.Windows.Media;‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Create properties for everything expected in the JSON definition of the heat map renderer class. This information is defined under heatmapRenderer in the Web map specification. The specification defines a "blurRadius" value, for example. This could be implemented with the following simple long property. Note that the name of the property in the class does not need to match the name in the specification.  public long BlurRadius { get; set; }‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Based on the specification, here are the properties (and corresponding data type) needed for the heat map renderer class: blurRadius (long) colorStops (list of objects) field (string) maxPixelIntensity (double) minPixelIntensity (double) type (string). OK, the list above looks pretty straightforward, except for the property that returns a list of objects. Go ahead and create properties for everything except colorStops (we'll circle back to that one).  The Type property needs to be set with "heatmap" as the default, as shown here. public string Type { get; set; } = "heatmap";‍‍‍‍‍‍‍‍‍‍‍‍‍‍ After you've defined the properties, in order to make them serializable you'll need to decorate them with the  JsonProperty attribute. The string you supply will be used in the output JSON and must match the name used in the Web map specification. Add the appropriate JsonProperty attribute to all properties, as shown below for the BlurRadius property. [JsonProperty("blurRadius")] public long BlurRadius { get; set; }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ The colorStops value is defined with a list of objects. What kind of object do we need here? In the specification, the JSON describes a colorStop class with two properties: color and ratio. You'll therefore need to create a new class with those properties. Let's call the class ColorStop. public partial class ColorStop {     [JsonProperty("ratio")]     public double Ratio { get; set; }     [JsonProperty("color")]     public int[] Color { get; set; } }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ The ratio property is a double. Color is a four value array (R, G, B, A). The constructor for ColorStop will accept a ratio (double) and a Color. The color values are used to set the array. public ColorStop(double ratio, Color color) {     Ratio = ratio;     Color = new int[] { color.R, color.G, color.B, color.A }; }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Return to the HeatMapRenderer class and add a property to hold the color stops. Initialize the property with an empty list of color stops. [JsonProperty("colorStops")] public List<ColorStop> ColorStops { get; set; } = new List<ColorStop>();‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Add some helper methods to add or clear color stops in the collection. public void AddColorStop(double ratio, Color color) {     if (ratio > 1.0 || ratio < 0.0) { throw new Exception("Argument 'ratio' must be a value between 0 and 1."); };     ColorStop stop = new ColorStop(ratio, color);     ColorStops.Add(stop); } public void ClearColorStops() {     ColorStops.Clear(); }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Finally, add a ToJson method that returns the JSON representation of the class. public string ToJson() {     return JsonConvert.SerializeObject(this); }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ You should now be able to use the new HeatMapRenderer class to write code like the following to apply a heat map renderer to a point feature layer! // Create a new HeatMapRenderer with info provided by the user. HeatMapRenderer heatMapRendererInfo = new HeatMapRenderer {     BlurRadius = blurRadius,     MinPixelIntensity = minIntensity,     MaxPixelIntensity = maxIntensity }; // Use a selected field to weight the point density if the user chooses to do so. if (UseFieldCheckBox.IsChecked == true) {     heatMapRendererInfo.Field = (FieldComboBox.SelectedValue as Field).Name; }  // Add the chosen color stops (plus transparent for empty areas). heatMapRendererInfo.AddColorStop(0.0, Colors.Transparent); heatMapRendererInfo.AddColorStop(0.10, (Color)StartColorComboBox.SelectedValue); heatMapRendererInfo.AddColorStop(1.0, (Color)EndColorComboBox.SelectedValue); // Get the JSON representation of the renderer class. string heatMapJson = heatMapRendererInfo.ToJson(); // Use the static Renderer.FromJson method to create a new renderer from the JSON string. var heatMapRenderer = Renderer.FromJson(heatMapJson); // Apply the renderer to a point layer in the map. _quakesLayer.Renderer = heatMapRenderer;‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ I'd agree with you if you think this is a lot of code to write to implement a heat map renderer. But remember, this class can be used in all your ArcGIS Runtime for .NET apps when you want to apply heat map rendering. Apologies if you were unable to successfully follow the steps above. Fortunately, the attached project contains the HeatMapRenderer class, as well as a WPF app for testing the heat map renderer. ... View more