geojson_vi 1.0.2

GeoJSON package for Dart developers to create, read, update and delete the geospatial data interchange format. This package is referenced originally from the specification document by H. Butler, M. Da [...]

example/geojson_vi_example.dart

import 'package:geojson_vi/geojson_vi.dart';

void main() {
  
  // ### Create a Feature with Point geometry
  
  // New GeoJSON
  final geoJSON = GeoJSON.create('example/data/new.geojson');

  // One position
  final pos = <double>[];
  pos.add(105.7743099);
  pos.add(21.0717561);
  // or pos.addAll([105.7743099,21.0717561]);

  // Create a Point geometry from one position
  final geom_point = GeoJSONPoint(pos);
  
  // Create a Feature
  final feature_point = GeoJSONFeature(geom_point);
  feature_point.properties['marker-color'] = '#7e7e7e';
  feature_point.properties['marker-size'] = 'medium';
  feature_point.properties['marker-symbol'] = 'college';
  feature_point.properties['title'] = 'Hanoi University of Mining and Geology';
  feature_point.properties['department'] = 'Geoinformation Technology';
  feature_point.properties['address'] = 'No.18 Vien Street - Duc Thang Ward- Bac Tu Liem District - Ha Noi';
  feature_point.properties['url'] = 'http://humg.edu.vn';

  // Add the feature to featureCollection
  geoJSON.featureCollection.features.add(feature_point);


  // ### Create a Feature with LineString geometry
  
  // LineString from 3 positions
  final pos1 = [105.7771289,21.0715458];
  final pos2 = [105.7745218,21.0715658];
  final pos3 = [105.7729125,21.0715358];
  
  // Create a LineString geometry from array of position
  final geom_line_string = GeoJSONLineString([pos1, pos2, pos3]);
  
  // Create a Feature 
  final feature_line_string = GeoJSONFeature(geom_line_string);
  feature_line_string.properties['stroke'] = '#7e7e7e';
  feature_line_string.properties['stroke-width'] = 2;
  feature_line_string.properties['stroke-opacity'] = 1;
  feature_line_string.properties['title'] = 'Vien St.';
  
  // Add the fearture to featureCollection
  geoJSON.featureCollection.features.add(feature_line_string);


  // ### Create a Feature with Polygon geometry
  
  // A linear ring is a closed LineString with four or more positions.
  // The first and last positions are equivalent, and they MUST contain
  // identical values; their representation SHOULD also be identical.
  final p01 = [105.7739666,21.0726795]; // The first position
  final p02 = [105.7739719,21.0721991];
  final p03 = [105.7743394,21.0721966];
  final p04 = [105.7743310,21.0725269];
  final p05 = [105.7742564,21.0726120];
  final p06 = [105.7741865,21.0726095];
  final p07 = [105.7741785,21.0726746];
  final p08 = [105.7739666,21.0726795]; // The last position

  //The exterior ring (boundary)
  final linerRing = [p01,p02,p03,p04,p05,p06,p07,p08];
  
  // Create a Polygon geometry from array of position
  final geom_polygon = GeoJSONPolygon([
    linerRing,
    // and others the interior rings (if present) bound holes within the surface
  ]);
  
  // Create a Feature
  final feature_polygon = GeoJSONFeature(geom_polygon);
  feature_polygon.properties['stroke'] = '#555555';
  feature_polygon.properties['stroke-width'] = 2;
  feature_polygon.properties['stroke-opacity'] = 1;
  feature_polygon.properties['fill'] = '#ab7942';
  feature_polygon.properties['fill-opacity'] = 0.5;
  feature_polygon.properties['title'] = 'HUMG\'s Office';

  // Add to featureCollection
  geoJSON.featureCollection.features.add(feature_polygon);

  geoJSON.save();
}