GeoJSON layer for Flutter Map
This package adds a GeoJsonLayer class, which can be added to a list
of layers in flutter_map to display data from a GeoJSON source. There
are convenience constructors for using GeoJSON data from an asset
or to download it from a website. The layer supports
simplespec
to style features according to their properties, and allows overriding
the defaults and filtering the features.
Getting started
The same as for all other packages: copy the package name and version
into your pubspec.yaml, and in your class, import the package:
import 'package:flutter_map_geojson2/flutter_map_geojson2.dart';
Usage
Pretty straightforward if you have used flutter_map before. Use the
layer like this:
@override
Widget build(BuildContext context) {
return FlutterMap(
options: MapOptions(...),
layers: [
GeoJsonLayer.memory({
'type': 'Feature',
'geometry': {
'type': 'LineString',
'coordinates': [
[24.7, 59.4],
[24.8, 59.401]
],
},
'properties': {
'stroke': '#22e',
'stroke-width': 11,
},
}),
],
);
}
Alternatively you can package a GeoJSON file in the assets (don't forget to
list them in pubspec.yaml) and add to your map like this:
layers: [
GeoJsonLayer.asset('data/overlay.geojson'),
],
To override marker and other object creation functions, see the corresponding
layer class arguments. You can have lines and polygons tappable by supplying
a hitNotifier object. For markers, you obviously can override the entire
thing.
Additional information
Note that there is no explicit error handling in the widget. Meaning, if you get broken data, it just won't be displayed without any notification. Broken GeoJSON features get silently skipped. If you have any ideas on how to do this properly, I'd love to hear them.
Thanks to flutter_map authors for the ultimate mapping solution for Flutter, and to Joze, the flutter_map_geojson author for the inspiration. This package differs from his in using cleaner API and recent Flutter Map features.