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geojson vi

geojson_vi: An Open-Source Dart and Flutter Library for Efficiently Handling GeoJSON Data in Compliance with RFC 7946 #

geojson_vi is an open-source library for Dart and Flutter developers, specifically designed to provide comprehensive support for the GeoJSON geospatial data interchange format as per the RFC 7946 standard. The software is a flexible, reliable tool that allows developers to parse, read, create, update, search, and delete geospatial data effectively.
Feature Highlights of geojson_vi #
Powerful Tools for Efficient GeoJSON Data Handling. Some of the primary ones include:

Parsing and Reading GeoJSON Data: geojson_vi allows developers to quickly parse and read GeoJSON data, ensuring full compliance with RFC 7946 standard.
Creating, Updating, Searching, and Deleting GeoJSON Data: With geojson_vi, developers can easily manipulate GeoJSON data, from creating new data entries to updating, searching, and deleting existing data.
Support for All GeoJSON Objects: geojson_vi offers comprehensive support for a wide range of Geometry types (GeoJSONPoint, GeoJSONMultiPoint, GeoJSONLineString, GeoJSONMultiLineString, GeoJSONPolygon, GeoJSONMultiPolygon, GeoJSONGeometryCollection), Feature, and FeatureCollection, making it a versatile tool for effectively managing diverse geospatial data.

GeoJSON UML Model #

Class structure of the geojson_vi library

Detailed Class Diagram of GeoJSON Geometry in the geojson_vi library

Usage #
Create GeoJSON object #
final map = {
'type': 'Point',
'coordinates': [105.77389, 21.0720414]
};

final jsonString =
'{"type": "Point", "coordinates": [105.78070163726807, 21.067921688241626]}';

final polygonCoordinates = [
[
[104.765625, 20.468189],
[106.545410, 20.468189],
[106.545410, 21.596150],
[104.765625, 21.596150],
[104.765625, 20.468189]
]
];

// Creating a GeoJSON object from data without knowing its type
final pointFromMap = GeoJSON.fromMap(map);

// Creating a GeoJSONPoint object from a JSON string when the type is known
final pointFromJSON = GeoJSONPoint.fromJSON(jsonString);

// Creating a GeoJSONGeometry object from data without knowing its type
final geometryFromMap = GeoJSONGeometry.fromMap(map);

// Creating a GeoJSONPoint object from a JSON string when the type is known
final geometryFromJSON = GeoJSONPoint.fromJSON(jsonString);

// Creating a GeoJSONPoint object from coordinates data
final pointFromCoordinates = GeoJSONPoint([105.77389, 21.0720414]);

// Creating a GeoJSONFeature object
final feature = GeoJSONFeature(
GeoJSONPoint([105.780701, 21.067921]),
properties: {
'title': 'Hanoi University of Mining and Geology',
'url': 'http://humg.edu.vn',
},
);

// Creating a GeoJSONFeatureCollection object
final featureCollection = GeoJSONFeatureCollection([]);
featureCollection.features.add(feature);

// Creating more GeoJSONFeature
final polygon = GeoJSONPolygon(polygonCoordinates);
final polygonFeature = GeoJSONFeature(polygon);
featureCollection.features.add(polygonFeature);
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Demo #
import 'package:geojson_vi/geojson_vi.dart';

void main() {
final featureCollection = GeoJSONFeatureCollection([]);
final point = GeoJSONPoint([105.7743099, 21.0717561]);
final feature = GeoJSONFeature(point, properties: {
'marker-color': '#7e7e7e',
'marker-size': 'medium',
'marker-symbol': 'college',
'title': 'Hanoi University of Mining and Geology',
'department': 'Geoinformation Technology',
'address':
'No.18 Vien Street - Duc Thang Ward - Bac Tu Liem District - Ha Noi, Vietnam',
'url': 'http://humg.edu.vn'
});
featureCollection.features.add(feature);
final pos1 = [105.7771289, 21.0715458];
final pos2 = [105.7745218, 21.0715658];
final pos3 = [105.7729125, 21.0715358];
final lineString = GeoJSONLineString([pos1, pos2, pos3]);
featureCollection.features.add(GeoJSONFeature(lineString, properties: {
'stroke': '#7e7e7e',
'stroke-width': 2,
'stroke-opacity': 1,
'title': 'Vien St.'
}));
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
final linerRing = [p01, p02, p03, p04, p05, p06, p07, p08];
featureCollection.features.add(
GeoJSONFeature(
GeoJSONPolygon([linerRing]),
properties: {
'stroke': '#555555',
'stroke-width': 2,
'stroke-opacity': 1,
'fill': '#ab7942',
'fill-opacity': 0.5,
'title': "HUMG's Office"
},
),
);
print(featureCollection.toJSON());
}
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Output: new.geojson
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {
"marker-color": "#7e7e7e",
"marker-size": "medium",
"marker-symbol": "college",
"title": "Hanoi University of Mining and Geology",
"department": "Geoinformation Technology",
"address": "No.18 Vien Street - Duc Thang Ward - Bac Tu Liem District - Ha Noi, Vietnam",
"url": "http://humg.edu.vn"
},
"geometry": {
"type": "Point",
"coordinates": [
105.7743099,
21.0717561
]
}
},
{
"type": "Feature",
"properties": {
"stroke": "#7e7e7e",
"stroke-width": 2,
"stroke-opacity": 1,
"title": "Vien St."
},
"geometry": {
"type": "LineString",
"coordinates": [
[
105.7771289,
21.0715458
],
[
105.7745218,
21.0715658
],
[
105.7729125,
21.0715358
]
]
}
},
{
"type": "Feature",
"properties": {
"stroke": "#555555",
"stroke-width": 2,
"stroke-opacity": 1,
"fill": "#ab7942",
"fill-opacity": 0.5,
"title": "HUMG's Office"
},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
105.7739666,
21.0726795
],
[
105.7739719,
21.0721991
],
[
105.7743394,
21.0721966
],
[
105.774331,
21.0725269
],
[
105.7742564,
21.072612
],
[
105.7741865,
21.0726095
],
[
105.7741785,
21.0726746
],
[
105.7739666,
21.0726795
]
]
]
}
}
]
}
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Quick viewing on geojson.io

Reference #
H. Butler, M. Daly, A. Doyle, S. Gillies, S. Hagen, and T. Schaub, "The GeoJSON Format", August 2016, https://tools.ietf.org/html/rfc7946.
Features and bugs #
Please file feature requests and bugs at the issue tracker.