flutter_map_geojson2 attribute filtering example

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_map_geojson2/flutter_map_geojson2.dart';
import 'package:flutter_map/flutter_map.dart';
import 'package:latlong2/latlong.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});
  // This widget is the root of your application.
  // @override
  Widget build(BuildContext context) {
    return MaterialApp(
      // Application name
      title: 'Flutter GeoJSON Demo',
      // Application theme data, you can set the colors for the application as
      // you want
      theme: ThemeData(
        // useMaterial3: false,
        primarySwatch: Colors.blue,
      ),
      // A widget which will be started on application startup
      home: PolygonFeatureCollection(title: 'Polygons Feature Collection'),
    );
  }
}

class PolygonFeatureCollection extends StatelessWidget {
  final String title;
  const PolygonFeatureCollection({super.key, required this.title});

  @override
  Widget build(BuildContext context) {
    GeoJsonStyleDefaults styleDefaults = GeoJsonStyleDefaults(
      strokeColor: Colors.red,
      strokeOpacity: 1,
      strokeWidth: 3,
      fillColor: Colors.blue,
    );
    return Scaffold(
      appBar: AppBar(
        // The title text which will be shown on the action bar
        title: Text(title),
      ),
      body: Center(
        child: FlutterMap(
          options: const MapOptions(
            initialCenter: LatLng(10.648822941560567, 13.269154369251979),
            initialZoom: 4.0,
          ),
          children: [
            GeoJsonLayer.asset(
              'assets/data/sample.geojson',
              onPolygon: (List<LatLng> points, List<List<LatLng>>? holes,
                  Map<String, dynamic> props,
                  {GeoJsonStyleDefaults? defaults}) {
                defaults ??= styleDefaults;

                final String colorHex = props['my_color'] ?? '';
                Color fillColor = defaults.fillColor;

                try {
                  fillColor =
                      Color(int.parse("0xFF${colorHex.replaceAll('#', '')}"));
                } catch (e) {
                  debugPrint("Invalid color: $colorHex");
                }

                return Polygon(
                    points: points,
                    holePointsList: holes,
                    color: fillColor,
                    borderColor: defaults.strokeColor,
                    borderStrokeWidth: 2.0);
              },
            ),
          ],
        ),
      ),
    );
  }
}

pubspec.yaml

name: fluttergeojsondemo
description: Flutter GeoJSON Demo.
publish_to: 'none'

version: 1.0.0+1

environment:
  sdk: ^3.0.0

dependencies:
  flutter:
    sdk: flutter
  flutter_map_geojson2: ^1.0.2
  flutter_map: ^7.0.2
  latlong2: ^0.9.1

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_lints: ^4.0.0

flutter:
  uses-material-design: true
  assets:
    - assets/data/sample.geojson