GeoJSON class

The GeoJSON text format for coordinate, geometry and feature objects.

Rules applied by the format conforms with the GeoJSON formatting of coordinate lists and geometries.

Examples:

• point (x, y):
  • {"type":"Point","coordinates":[10.1,20.2]}
• point (x, y, z):
  • {"type":"Point","coordinates":[10.1,20.2,30.3]}
• box (min-x, min-y, max-x, max-y), as a property inside other object:
  • "bbox": [10.1,10.1,20.2,20.2]
• box (min-x, min-y, min-z, max-x, max-y, maz-z), as a property:
  • "bbox": [10.1,10.1,10.1,20.2,20.2,20.2]

Multi point (with 2D points): {"type":"MultiPoint","coordinates":[[10.1,10.1],[20.2,20.2],[30.3,30.3]]}

Line string (with 2D points): {"type":"LineString","coordinates":[[10.1,10.1],[20.2,20.2],[30.3,30.3]]}

Multi line string (with 2D points):

  {"type":"MultiLineString",
   "coordinates":[[[10.1,10.1],[20.2,20.2],[30.3,30.3]]]}

Polygon (with 2D points):

  {"type":"Polygon",
   "coordinates":[[[35,10],[45,45],[15,40],[10,20],[35,10]]]}

MultiPolygon (with 2D points):

  {"type":"Polygon",
   "coordinates":[[[[35,10],[45,45],[15,40],[10,20],[35,10]]]]}

Feature:

  {"type": "Feature",
   "id":1,
   "properties": {"prop1": 100},
   "geometry": {"type":"Point","coordinates":[10.1,20.2]}}

The GeoJSON specification about M coordinates: "Implementations SHOULD NOT extend positions beyond three elements because the semantics of extra elements are unspecified and ambiguous. Historically, some implementations have used a fourth element to carry a linear referencing measure (sometimes denoted as "M") or a numerical timestamp, but in most situations a parser will not be able to properly interpret these values. The interpretation and meaning of additional elements is beyond the scope of this specification, and additional elements MAY be ignored by parsers."

This implementation allows printing M coordinates, when available on source data. Such M coordinate values are always formatted as "fourth element.". However, it's possible that other implementations cannot read them:

• point (x, y, m), with z missing but formatted as 0, and m = 40.4:
  • {"type":"Point","coordinates":[10.1,20.2,0,40.4]}
• point (x, y, z, m), with z = 30.3 and m = 40.4:
  • {"type":"Point","coordinates":[10.1,20.2,30.3,40.4]}

When getting an encoder from text writer format objects this GeoJSON class provides you can use crs parameter to give hints (like axis order, and whether x and y must be swapped when writing) about coordinate reference system in text output. When crs is available then crs.swapXY is used to determine whether swapping (x/longitude <-> y/latitude) should occur.

See also the GeoJSONL format for decoding and encoding GeoJSON features in a text sequence with features delimited by line feeds.

Constructors

GeoJSON()

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

coordinateFormat({GeoJsonConf? conf}) → TextWriterFormat<CoordinateContent>

The GeoJSON text format (encoding only) for coordinate objects with optional conf.

featureFormat({GeoJsonConf? conf}) → TextFormat<FeatureContent>

The GeoJSON text format (encoding and decoding) for feature objects with optional conf.

geometryFormat({GeoJsonConf? conf}) → TextFormat<GeometryContent>

The GeoJSON text format (encoding and decoding) for geometry objects with optional conf.

Constants

contentType → const String

The content type (application/geo+json) for GeoJSON by RFC 7946.

coordinate → const TextWriterFormat<CoordinateContent>

The GeoJSON text format (encoding only) for coordinate objects.

feature → const TextFormat<FeatureContent>

The GeoJSON text format (encoding and decoding) for feature objects.

geometry → const TextFormat<GeometryContent>

The GeoJSON text format (encoding and decoding) for geometry objects.