geocore 0.6.0

Geospatial data structures (features, geometry and metadata) and utilities (GeoJSON parser) for Dart.

example/geocore_example.dart

// Copyright (c) 2020-2021 Navibyte (https://navibyte.com). All rights reserved.
// Use of this source code is governed by a “BSD-3-Clause”-style license that is
// specified in the LICENSE file.
//
// Docs: https://github.com/navibyte/geospatial

// ignore_for_file: avoid_print, avoid_redundant_argument_values

import 'package:equatable/equatable.dart';

import 'package:geocore/geocore.dart';

/*
To test run this from command line: 

dart example/geocore_example.dart
*/

void main() {
  // configure Equatable to apply toString() default impls
  EquatableConfig.stringify = true;

  // call simple demos
  _parseGeoJSON();
  _basicStructures();
}

void _parseGeoJSON() {
  print('Parse GeoJSON sample data.');

  // sample GeoJSON data
  const sample = '''
    {
      "type": "FeatureCollection",
      "features": [
        {
          "type": "Feature",
          "id": "ROG",
          "geometry": {
            "type": "Point",
            "coordinates": [-0.0014, 51.4778, 45.0]  
          },
          "properties": {
            "title": "Royal Observatory",
            "place": "Greenwich",
            "city": "London",
            "isMuseum": true,
            "code": "000",
            "founded": 1675,
            "prime": "1884-10-22", 
            "measure": 5.79
          }
        }  
      ]
    }
  ''';

  // parse FeatureCollection using the default GeoJSON factory
  final fc = geoJSON.featureCollection(sample);

  // loop through features and print id, geometry and properties for each
  for (final f in fc.features) {
    print('Feature with id: ${f.id}');
    print('  geometry: ${f.geometry}');
    print('  properties:');
    for (final key in f.properties.keys) {
      print('    $key: ${f.properties[key]}');
    }
  }
}

void _basicStructures() {
  print('');
  print('Create some basic data structures.');

  // Geospatial feature with id, geometry and properties
  print(Feature.view(
    id: 'ROG',
    geometry: GeoPoint3.from([-0.0014, 51.4778, 45.0]),
    properties: <String, dynamic>{
      'title': 'Royal Observatory',
      'place': 'Greenwich',
      'city': 'London',
      'isMuseum': true,
      'code': '000',
      'founded': 1675,
      'prime': DateTime.utc(1884, 10, 22),
      'measure': 5.79,
    },
  ));

  // Geographic points (lon-lat, lon-lat-m, lon-lat-elev, lon-lat-elev-m)
  print(GeoPoint2.lonLat(-0.0014, 51.4778));
  print(GeoPoint2m.lonLatM(-0.0014, 51.4778, 123.0));
  print(GeoPoint3.lonLatElev(-0.0014, 51.4778, 45.0));
  print(GeoPoint3m.lonLatElevM(-0.0014, 51.4778, 45.0, 123.0));

  // Geographic points (lat-lon, lat-lon-m, lat-lon-elev, lat-lon-elev-m)
  print(GeoPoint2.latLon(51.4778, -0.0014));
  print(GeoPoint2m.latLonM(51.4778, -0.0014, 123.0));
  print(GeoPoint3.latLonElev(51.4778, -0.0014, 45.0));
  print(GeoPoint3m.latLonElevM(51.4778, -0.0014, 45.0, 123.0));

  // Geographic bounds represented as Bounds<GeoPoint>
  print(Bounds.of(
      min: GeoPoint2.lonLat(-180.0, -90.0),
      max: GeoPoint2.lonLat(180.0, 90.0)));
  print(Bounds.of(
      min: GeoPoint3.lonLatElev(-180.0, -90.0, 50.0),
      max: GeoPoint3.lonLatElev(180.0, 90.0, 100.0)));
  print(Bounds.of(
      min: GeoPoint2.latLon(-90.0, -180.0),
      max: GeoPoint2.latLon(90.0, 180.0)));

  // Geographic bounds as GeoBounds (that implements Bounds<GeoPoint>)
  print(GeoBounds.world());
  print(GeoBounds.bboxLonLat(-180.0, -90.0, 180.0, 90.0));
  print(GeoBounds.bboxLonLatElev(-180.0, -90.0, 50.0, 180.0, 90.0, 100.0));

  // Projected points (XY, XYM, XYZ and XYZM) using doubles
  print(Point2.xy(708221.0, 5707225.0));
  print(Point2m.xym(708221.0, 5707225.0, 123.0));
  print(Point3.xyz(708221.0, 5707225.0, 45.0));
  print(Point3m.xyzm(708221.0, 5707225.0, 45.0, 123.0));

  // Projected points (XY, XYZ) using integers
  print(Point2i.xy(708221, 5707225));
  print(Point3i.xyz(708221, 5707225, 45));

  // Series of points containg all types of points
  final points = PointSeries<Point>.view([
    // coords stored as double, GeoPoint3 implements Point<double>
    GeoPoint3.origin(),
    // coords stored as num (given as double or int),
    // Point2 implements Point<num>
    Point2.xy(708221.0, 5707225),
    // coords stored as int, Point3i implements Point<int>
    Point3i.xyz(708221, 5707225, 45)
  ]);
  print(points);
  print('Testing int coord value: '
      '${points[2].x} ${points[2].y} (type: ${points[2].z.runtimeType})');

  // Temporal intervals (open, open-started, open-ended, closed)
  print(Interval.open());
  print(Interval.openStart(DateTime.utc(2020, 10, 31)));
  print(Interval.openEnd(DateTime.utc(2020, 10, 01)));
  print(
      Interval.closed(DateTime.utc(2020, 10, 01), DateTime.utc(2020, 10, 31)));

  // Temporal instant
  print(Instant.parse('2020-10-31'));

  // Coordinate reference system (identifiers)
  print(CRS84);
  print(CRS84h);
  print(CRS.id('urn:ogc:def:crs:EPSG::4326'));

  // Extent with spatial and temporal parts
  print(Extent.single(
    crs: CRS84,
    bounds: GeoBounds.bboxLonLat(-180.0, -90.0, 180.0, 90.0),
    interval: Interval.fromJson(<dynamic>['..', '2020-10-31']),
  ));
}