geobase 0.1.0-a.1

Geospatial data (features, geometries, coordinates) writers (GeoJSON, WKT) for Dart.

Geospatial data writers

The package provides data writers for geospatial features, geometries, coordinates and properties. Currently the supported formats are GeoJSON and WKT (Well-known text representation of geometry).

There are also data structures to represent positions and bounding boxes, both for geographic coordinate systems and projected (or cartesian) coordinate systems.

Features

• 🔢 enums for geospatial coordinate and geometry types
• 🌐 geographic positions and bounding boxes (longitude-latitude-elevation)
• 🗺️ projected positions and bounding boxes (cartesian XYZ)
• 📃 geospatial data writers for features, geometries, coordinates, properties:
  • 🌎 supported formats: GeoJSON
• 📃 geospatial data writers for geometries and coordinates:
  • 🪧 supported formats: WKT

This package is at BETA stage, interfaces not fully final yet.

Getting started

The package requires at least Dart SDK 2.12, and it supports all Dart and Flutter platforms.

Usage

Add the dependency in your pubspec.yaml:

dependencies:
  geobase: ^0.1.0-a.1

Import it:

import `package:geobase/geobase.dart`

A sample to write a Point geometry to WKT (with z and m coordinates too):

  // geometry writer for WKT
  final writer = wktFormat().geometriesToText();

  // prints:
  //    POINT ZM(10.123 20.25 -30.95 -1.999)
  print(
    writer
      ..geometryWithPosition(
        type: Geom.point,
        coordType: Coords.xyzm,
        coordinates: const Position(x: 10.123, y: 20.25, z: -30.95, m: -1.999),
      )
      ..toString(),
  );

A sample to write a LineString geometry to GeoJSON:

  // geometry writer for GeoJSON
  final writer = geoJsonFormat().geometriesToText();

  // prints (however without line breaks):
  //    {"type":"LineString",
  //     "bbox":[-1.1,-3.49,3.5,-1.1],
  //     "coordinates":[[-1.1,-1.1],[2.1,-2.5],[3.5,-3.49]]}
  print(
    writer
      ..geometryWithPositions1D(
        type: Geom.lineString,
        bbox: const GeoBox(west: -1.1, south: -3.49, east: 3.5, north: -1.1),
        coordinates: [
          const GeoPosition(lon: -1.1, lat: -1.1),
          const GeoPosition(lon: 2.1, lat: -2.5),
          const GeoPosition(lon: 3.5, lat: -3.49),
        ],
      )
      ..toString(),
  );

A sample to write a Feature geometry to GeoJSON:

  // feature writer for GeoJSON
  final writer = geoJsonFormat().featuresToText();

  // prints (however without line breaks):
  //    {"type":"Feature",
  //     "id":"fid-1",
  //     "geometry":
  //        {"type":"Point","coordinates":[10.123,20.25]},
  //     "properties":
  //        {"foo":100,"bar":"this is property value","baz":true}}
  print(
    writer
      ..feature(
        id: 'fid-1',
        geometries: (gw) => gw.geometryWithPosition(
          type: Geom.point,
          coordinates: const GeoPosition(lon: 10.123, lat: 20.25),
        ),
        properties: {
          'foo': 100,
          'bar': 'this is property value',
          'baz': true,
        },
      )
      ..toString(),
  );

Package

This is a Dart package named geobase under the geospatial code repository.

See also the geocore package for geometry and feature data structures, data parsers, coordinate transformations and other utitilies.

Authors

This project is authored by Navibyte.

More information and other links are available at the geospatial repository from GitHub.

License

This project is licensed under the "BSD-3-Clause"-style license.

Please see the LICENSE.