Save graphics overlays?

Question

We would like to save the graphics overlays on a map and allow a user to add them back to a map at a later time.  I did not see any functionality in the SDK for persisting the overlays.  Without writing a lot of custom code, is it possible to save the overlays or even the complete map with the overlays?

JoeHershman · Answer

You could make it really clean and roll your own ToJson public static class OverlayExtension { public static string ToJson(this GraphicsOverlay overlay) { JArray array = new JArray(); foreach (var graphic in overlay.Graphics) { JProperty geometry = new JProperty("geometry", graphic.Geometry.ToJson()); JProperty symbol = new JProperty("symbol", graphic.Symbol.ToJson()); JObject jObject = new JObject(geometry, symbol); array.Add(jObject); } return array.ToString(); } public static void FromJson(this GraphicsOverlay overlay, string json) { JArray array = JArray.Parse(json); foreach (var jObject in array.OfType<JObject>()) { string geometry = jObject["geometry"].ToString(); string symbol = jObject["symbol"].ToString(); var graphic = new Graphic(Geometry.FromJson(geometry), Symbol.FromJson(symbol)); overlay.Graphics.Add(graphic); } } }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Then in code string json = EditGraphicsOverlay.ToJson(); //Write to file //read from file EditGraphicsOverlay.FromJson(json);‍‍‍‍‍‍‍‍‍‍

JoeHershman · Answer

I think it would be pretty straight forward to just build out your own json array for each element using the .ToJson methods. Something like... // Save to file JArray array = new JArray(); foreach (var graphic in overlay.Graphics) { JProperty geometry = new JProperty("geometry", graphic.Geometry.ToJson()); JProperty symbol = new JProperty("symbol", graphic.Symbol.ToJson()); JObject jObject = new JObject(geometry, symbol); array.Add(jObject); } StreamWriter sw = new StreamWriter("D:\outfile.json"); JsonWriter writer = new JsonTextWriter(sw); array.WriteTo(writer); writer.Close(); //read back in StreamReader reader = new StreamReader("D:\outfile.json"); string json = reader.ReadToEnd(); JArray array = JArray.Parse(json); foreach (var d in array.OfType<JObject>()) { string geo = d["geometry"].ToString(); string sym = d["symbol"].ToString(); var graph = new Graphic(Geometry.FromJson(geo), Symbol.FromJson(sym)); overlay.Graphics.Add(graph); }‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

JonShuler · Answer

We are using the API to sketch shapes (polygon, point, etc) on the map.  I found that the the Graphics object has a ToJson() for the geometry and symbol data so looking into using that.  I will also look into FeatureCollection.