private async Task GetPolygonData()
{
var country = await _dbContext.Countries.FirstOrDefaultAsync();
//Geometry to geoJSON
var lines = new List <GeoJSON.Net.Geometry.LineString>();
var polygon = country.Border as NetTopologySuite.Geometries.Polygon;
List <Coordinate[]> res = new List <Coordinate[]>();
res.Add(polygon.Shell.Coordinates);
foreach (ILineString interiorRing in polygon.InteriorRings)
{
res.Add(interiorRing.Coordinates);
}
foreach (var line in res)
{
var coordinates = new List <IPosition>();
foreach (var item in line)
{
coordinates.Add(new Position(item.X, item.Y, item.Z));
}
lines.Add(new GeoJSON.Net.Geometry.LineString(coordinates));
}
GeoJSON.Net.Geometry.Polygon jsonPolygon = new GeoJSON.Net.Geometry.Polygon(lines);
var s = JsonConvert.SerializeObject(jsonPolygon);
//Geometry to wkt
var writer = new NetTopologySuite.IO.WKTWriter();
var s2 = writer.Write(country.Border);
Console.WriteLine($"GeoJSON结果:{s},WKT结果:{s2}");
}
public IActionResult GetPolygon(int countryId)
{
var country = _dbContext.Countries.FirstOrDefault(x => x.CountryID == countryId);
if (country == null)
{
return(Json($"查询不到id为{countryId}的国家"));
}
//Geometry to GeoJSON
//https://nettopologysuite.github.io/html/class_net_topology_suite_1_1_geometries_1_1_polygon.html
//https://github.com/synhershko/nettopologysuite/blob/master/NetTopologySuite.IO/NetTopologySuite.IO.GeoJSON/Converters/GeometryConverter.cs
//->已copy到GeometryConverter和GeometryArrayConverter
var lines = new List <GeoJSON.Net.Geometry.LineString>();
var polygon = country.Border as NetTopologySuite.Geometries.Polygon;
List <Coordinate[]> res = new List <Coordinate[]>();
res.Add(polygon.Shell.Coordinates);
foreach (ILineString interiorRing in polygon.InteriorRings)
{
res.Add(interiorRing.Coordinates);
}
foreach (var line in res)
{
var coordinates = new List <IPosition>();
foreach (var item in line)
{
coordinates.Add(new Position(item.X, item.Y, item.Z));
}
lines.Add(new GeoJSON.Net.Geometry.LineString(coordinates));
}
GeoJSON.Net.Geometry.Polygon jsonPolygon = new GeoJSON.Net.Geometry.Polygon(lines);
var s = JsonConvert.SerializeObject(jsonPolygon);
//Geometry to wkt
//点和线的是静态方法，面的是方法_(:з」∠)_
var writer = new NetTopologySuite.IO.WKTWriter();
var s2 = writer.Write(country.Border);
return(Json($"GeoJSON结果:{s},WKT结果:{s2}"));
}
