public override GeoJSONObject ReadJson(JsonReader reader, Type objectType, GeoJSONObject existingValue, bool hasExistingValue, JsonSerializer serializer)
{
if (reader.TokenType == JsonToken.Null) //GeoJSONObject can be abstract
{
return(null);
}
JObject token = JObject.Load(reader);
if (!token.TryGetValue("type", StringComparison.OrdinalIgnoreCase, out JToken TypeToken))
{
throw new JsonReaderException("Invalid geojson object, does not have 'type' field.");
}
// Match GeoJSONType to actual type
GeoJSONType tokenType = TypeToken.ToObject <GeoJSONType>(serializer);
Type actualType = tokenType switch
{
GeoJSONType.Point => typeof(Point),
GeoJSONType.LineString => typeof(LineString),
GeoJSONType.Polygon => typeof(Polygon),
GeoJSONType.Feature => typeof(Feature),
GeoJSONType.FeatureCollection => typeof(FeatureCollection),
_ => null, //TODO: proper check here
};
if (existingValue == null || existingValue.GetType() != actualType)
{
return((GeoJSONObject)token.ToObject(actualType, serializer));
}
else
{
using (JsonReader derivedTypeReader = token.CreateReader())
{
serializer.Populate(derivedTypeReader, existingValue);
}
return(existingValue);
}
}
public async Task NavigateToNewEditPage(GeoJSONType type)
{
Page currentPage = GetCurrentPage();
await currentPage.Navigation.PushModalAsync(new EditFeatureView(new EditFeatureViewModel(type)));
}
protected GeoJSONObject(GeoJSONType type) => Type = type;
/// <summary>
/// 创建GeometryGeoJson对象，并对Type进行赋值
/// </summary>
/// <param name="type"></param>
public GeometryGeoJson(GeoJSONType type)
{
this.Type = type;
}
