地理空間 - Flutter SDK

final smallCircle =
    GeoCircle(GeoPoint(lon: -121.9, lat: 47.3), 0.25.degrees);
final largeCircleCenter = GeoPoint(lon: -122.6, lat: 47.8);
// The SDK provides convenience methods to convert measurements to radians.
final radiusFromKm = GeoDistance.fromKilometers(44.4);
final largeCircle = GeoCircle(largeCircleCenter, radiusFromKm);

final largeBox = GeoBox(
    GeoPoint(lon: -122.7, lat: 47.3), GeoPoint(lon: -122.1, lat: 48.1));
final smallBoxSouthWest = GeoPoint(lon: -122.4, lat: 47.5);
final smallBoxNorthEast = GeoPoint(lon: -121.8, lat: 47.9);
final smallBox = GeoBox(smallBoxSouthWest, smallBoxNorthEast);

// To store geospatial data, create an embedded object with this structure.
// Name it whatever is most convenient for your application.
@RealmModel(ObjectType.embeddedObject)
class _MyGeoPoint {
  // These two properties are required to persist geo data.
  final String type = 'Point';
  final List<double> coordinates = const [];
  // You can optionally implement convenience methods to simplify
  // creating and working with geospatial data.
  double get lon => coordinates[0];
  set lon(double value) => coordinates[0] = value;
  double get lat => coordinates[1];
  set lat(double value) => coordinates[1] = value;
  GeoPoint toGeoPoint() => GeoPoint(lon: lon, lat: lat);
}

// Use the GeoJSON-compatible class as a property in your model.
@RealmModel()
class _Company {
  @PrimaryKey()
  late ObjectId id;
  _MyGeoPoint? location;
}

final realm =
    Realm(Configuration.local([MyGeoPoint.schema, Company.schema]));
realm.write(() {
  realm.addAll([
    Company(
      firstCompanyID,
      location: MyGeoPoint(coordinates: [-122.35, 47.68]),
    ),
    Company(
      secondCompanyID,
      location: MyGeoPoint(coordinates: [-121.85, 47.9]),
    )
  ]);
});