Add custom dynamic entity data source

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 // Copyright 2023 Esri. // // Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. // You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific // language governing permissions and limitations under the License.  using Esri.ArcGISRuntime.Data; using Esri.ArcGISRuntime.Geometry; using Esri.ArcGISRuntime.RealTime; using System; using System.Collections.Generic; using System.Diagnostics; using System.IO; using System.Linq; using System.Text.Json; using System.Threading; using System.Threading.Tasks;  namespace ArcGIS.WPF.Samples.AddCustomDynamicEntityDataSource {  public class SimulatedDataSource : DynamicEntityDataSource  {  // Hold a reference to the file stream reader, the process task, and the cancellation token source.  private Task _processTask;  private StreamReader _streamReader;  private CancellationTokenSource _cancellationTokenSource;  private List<Field> _fields;   public SimulatedDataSource(string filePath, string entityIdField, TimeSpan delay)  {  FilePath = filePath;  EntityIdField = entityIdField;  Delay = delay;  }   #region Properties   // Expose the file path, entity ID field, and delay length as properties.  public string FilePath { get; }  public string EntityIdField { get; }  public TimeSpan Delay { get; }   #endregion Properties   protected override Task<DynamicEntityDataSourceInfo> OnLoadAsync()  {  return Task.Run(() =>  {  // Derive schema from the first row in the custom data source.  _fields = GetSchema();   // Open the file for processing.  Stream stream = File.OpenRead(FilePath);  _streamReader = new StreamReader(stream);   // Create a new DynamicEntityDataSourceInfo using the entity ID field and the fields derived from the attributes of each observation in the custom data source.  return new DynamicEntityDataSourceInfo(EntityIdField, _fields) { SpatialReference = SpatialReferences.Wgs84 };  });  }   protected override Task OnConnectAsync(CancellationToken cancellationToken)  {  // On connecting to the custom data source begin processing the file.  _cancellationTokenSource = new CancellationTokenSource();  _processTask = Task.Run(() => ObservationProcessLoopAsync(), _cancellationTokenSource.Token);  return Task.CompletedTask;  }   protected override async Task OnDisconnectAsync()  {  // On disconnecting from the custom data source, stop processing the file.  _cancellationTokenSource?.Cancel();   if (_processTask != null) await _processTask;   _cancellationTokenSource = null;  _processTask = null;  }   private async Task ObservationProcessLoopAsync()  {  try  {  while (!_cancellationTokenSource.IsCancellationRequested)  {  // Process the next observation.  var processed = await ProcessNextObservation();   // If the end of the file has been reached, break out of the loop.  if (_streamReader.EndOfStream) break;   // If the observation was not processed, continue to the next observation.  if (!processed) continue;   // If there is no delay, yield to the UI thread otherwise delay for the specified amount of time.  if (Delay == TimeSpan.Zero)  {  await Task.Yield();  }  else  {  await Task.Delay(Delay, _cancellationTokenSource.Token);  }  }  }  catch (Exception ex)  {  Debug.WriteLine(ex.ToString());  }  }   private async Task<bool> ProcessNextObservation()  {  _ = _streamReader ?? throw new ArgumentNullException("File stream not available.");   // Read the next observation.  var json = await _streamReader.ReadLineAsync();   // If there is no json to read or the schema is not available, return false.  if (string.IsNullOrEmpty(json) || _fields is null) return false;   try  {  JsonElement jsonElement = JsonSerializer.Deserialize<JsonElement>(json);   // Create a new MapPoint from the x and y coordinates of the observation.  MapPoint point = null;  if (jsonElement.TryGetProperty("geometry", out JsonElement jsonGeometry))  {  point = new MapPoint(  jsonGeometry.GetProperty("x").GetDouble(),  jsonGeometry.GetProperty("y").GetDouble(),  SpatialReferences.Wgs84);  }   // Get the dictionary of attributes from the observation using the field names as keys.  Dictionary<string, object> attributes = new Dictionary<string, object>();  if (jsonElement.TryGetProperty("attributes", out JsonElement jsonAttributes))  {  foreach (var field in _fields)  {  if (jsonAttributes.TryGetProperty(field.Name, out JsonElement prop))  {  object value = null;  if (prop.ValueKind != JsonValueKind.Null)  {  if (prop.ValueKind == JsonValueKind.Number && field.FieldType == FieldType.Float64)  {  value = prop.GetDouble();  }  else if (prop.ValueKind == JsonValueKind.Number && field.FieldType == FieldType.Int32)  {  value = prop.GetInt32();  }  else if (prop.ValueKind == JsonValueKind.String)  {  value = prop.GetString();  }  }  attributes.Add(field.Name, value);  }  }  }   // Add the observation to the custom data source.  AddObservation(point, attributes);  return true;  }  catch (Exception ex)  {  Debug.WriteLine($"{ex}");  return false;  }  }   private static List<Field> GetSchema()  {  // Return a list of fields matching the attributes of each observation in the custom data source.  return new List<Field>()  {  new Field(FieldType.Text, "MMSI", string.Empty, 256),  new Field(FieldType.Float64, "BaseDateTime", string.Empty, 8),  new Field(FieldType.Float64, "LAT", string.Empty, 8),  new Field(FieldType.Float64, "LONG", string.Empty, 8),  new Field(FieldType.Float64, "SOG", string.Empty, 8),  new Field(FieldType.Float64, "COG", string.Empty, 8),  new Field(FieldType.Float64, "Heading", string.Empty, 8),  new Field(FieldType.Text, "VesselName", string.Empty, 256),  new Field(FieldType.Text, "IMO", string.Empty, 256),  new Field(FieldType.Text, "CallSign", string.Empty, 256),  new Field(FieldType.Text, "VesselType", string.Empty, 256),  new Field(FieldType.Text, "Status", string.Empty, 256),  new Field(FieldType.Float64, "Length", string.Empty, 8),  new Field(FieldType.Float64, "Width", string.Empty, 8),  new Field(FieldType.Text, "Cargo", string.Empty, 256),  new Field(FieldType.Text, "globalid", string.Empty, 256)  };  }  } }