/// <summary>
/// A way to add a multipolygon. Avoids erroneous conversion from multiple polygons containing holes to a simple list of coordinates.
/// </summary>
public async Task Add(GeoJsonMultiPolygonJsonString geoJsonMultiPolygonJsonString, Catchment otherCatchmentInfo)
{
var geographyFactory = await this.GeometryFactoryProvider.GetGeometryFactoryAsync();
var multiPolygonGeometry = geoJsonMultiPolygonJsonString.ToMultiPolygon(geographyFactory);
var catchmentEntity = new Entities.Catchment {
Identity = otherCatchmentInfo.Identity.Value,
Name = otherCatchmentInfo.Name,
Boundary = multiPolygonGeometry,
};
await this.AddCatchmentEntity(catchmentEntity, otherCatchmentInfo.Identity);
}
public static GeoJsonMultiPolygonJsonString ToGeoJsonMultiPolygonJsonString(this MultiPolygon multiPolygon)
{
var geoJsonSerializer = GeoJsonSerializer.Create();
using (var stringWriter = new StringWriter())
using (var jsonWriter = new JsonTextWriter(stringWriter))
{
geoJsonSerializer.Serialize(jsonWriter, multiPolygon);
var geoJsonMultiPolygonJsonStringValue = stringWriter.ToString();
var geoJsonMultiPolygonJsonString = GeoJsonMultiPolygonJsonString.From(geoJsonMultiPolygonJsonStringValue);
return(geoJsonMultiPolygonJsonString);
}
}
public async Task SetBoundary(CatchmentIdentity identity, GeoJsonMultiPolygonJsonString newGeoJsonMultiPolygonJsonString)
{
var geographyFactory = await this.GeometryFactoryProvider.GetGeometryFactoryAsync();
var newMultiPolygonGeometry = newGeoJsonMultiPolygonJsonString.ToMultiPolygon(geographyFactory);
await this.ExecuteInContextAsync(async dbContext =>
{
var entity = await dbContext.Catchments.GetByIdentity(identity).SingleAsync();
entity.Boundary = newMultiPolygonGeometry;
await dbContext.SaveChangesAsync();
});
}
public static async Task <CatchmentIdentity> Add(this ICatchmentsRepository repository, string name, GeoJsonMultiPolygonJsonString geoJsonMultiPolygonJsonString)
{
var catchmentIdentity = CatchmentIdentity.New();
var catchment = new Catchment()
{
Identity = catchmentIdentity,
Name = name,
};
await repository.Add(geoJsonMultiPolygonJsonString, catchment);
return(catchmentIdentity);
}
/// <summary>
/// Use a geometry factory to convert a multipolygon geojson string into a multipolygon.
/// NOTE: this requires that the keys 'type' and 'coordinates' be all-lowercase.
/// </summary>
public static MultiPolygon ToMultiPolygon(this GeoJsonMultiPolygonJsonString geoJsonMultiPolygonJsonString, IGeometryFactory geometryFactory)
{
// Deserialize string to a JObject.
var jObject = JObject.Parse(geoJsonMultiPolygonJsonString.Value);
// Test that the type *IS* multipolygon!
var geometryTypeValue = jObject["type"].Value <string>();
if (geometryTypeValue.ToLowerInvariant() != "multipolygon")
{
throw new ArgumentException("Input GeoJSON is not a multipolygon.", nameof(GeoJsonMultiPolygonJsonString));
}
// Create the linear rings.
var coordinatesToken = jObject["coordinates"];
var polygons = new List <IPolygon>();
foreach (var polygonValues in coordinatesToken.AsJEnumerable())
{
ILinearRing shell = null;
var holes = new List <ILinearRing>();
var isFirst = true;
foreach (var linearRingValues in polygonValues.AsJEnumerable())
{
var coordinateValues = linearRingValues.ToObject <double[][]>();
var coordinates = new List <Coordinate>();
foreach (var coordinateValue in coordinateValues)
{
// X is longitude.
var coordinate = new Coordinate(coordinateValue[0], coordinateValue[1]);
coordinates.Add(coordinate);
}
var linearRing = geometryFactory.CreateLinearRing(coordinates.ToArray());
if (isFirst)
{
isFirst = false;
// The first linear ring is assumed to be the outside shell and must be counter-clockwise for the SQL server database (to enclose a limited space, instead of the whole world but the space).
shell = linearRing.IsCCW ? linearRing : linearRing.Reverse() as LinearRing;
}
else
{
// Holes must be clockwise for the SQL server database.
var hole = linearRing.IsCCW ? linearRing.Reverse() as LinearRing : linearRing;
holes.Add(hole);
}
}
// Create the polygon.
var polygon = geometryFactory.CreatePolygon(shell, holes.ToArray());
polygons.Add(polygon);
}
// Create the multipolygon.
var multiPolygon = geometryFactory.CreateMultiPolygon(polygons.ToArray()) as MultiPolygon;
return(multiPolygon);
}
