Draw Shapes on Map

_{Last updated: July 15, 2026 | 3 minutes read}

This example presents how to create a Flutter app that draws and displays shapes like polylines, polygons, and points on a map using Maps SDK for Flutter.

How it works

The example app demonstrates the following features:

• Draw and display polylines, polygons, and points on the map.
• Handle user interaction through app bar buttons.

Polygon drawing

Polyline drawing

Points drawing

UI and Map Integration

This code defines the main UI elements, including the map and an app bar with buttons to draw polylines, polygons, and points on the map.

main.dartView on Github

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Draw Shapes',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late GemMapController _mapController;

  @override
  void dispose() {
    GemKit.release();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.deepPurple[900],
        title: const Text('Draw Shapes', style: TextStyle(color: Colors.white)),
        actions: [
          IconButton(
            onPressed: _onPolylineButtonPressed,
            icon: const Icon(Icons.adjust, color: Colors.white),
          ),
          IconButton(
            onPressed: _onPolygonButtonPressed,
            icon: const Icon(Icons.change_history, color: Colors.white),
          ),
          IconButton(
            onPressed: _onPointsButtonPressed,
            icon: const Icon(Icons.more_horiz, color: Colors.white),
          ),
        ],
      ),
      body: GemMap(
        key: ValueKey("GemMap"),
        onMapCreated: _onMapCreated,
        appAuthorization: projectApiToken,
      ),
    );
  }

Drawing and Displaying Shapes

This code snippet defines the methods to draw and display different shapes (polyline, polygon, points) on the map. Each method creates a MarkerCollection , adds markers with specific coordinates, and displays them on the map.

main.dartView on Github

  void _onMapCreated(GemMapController controller) async {
    // Save controller for further usage.
    _mapController = controller;
  }

  // Method to draw and center on a polyline
  void _onPolylineButtonPressed() {
    // Create a marker collection
    final markerCollection = MarkerCollection(
      markerType: MarkerType.polyline,
      name: 'Polyline marker collection',
    );

    // Set coordinates of marker
    final marker = Marker();
    marker.setCoordinates([
      Coordinates(latitude: 52.360495, longitude: 4.936882),
      Coordinates(latitude: 52.360495, longitude: 4.836882),
    ]);
    markerCollection.add(marker);

    _showMarkerCollectionOnMap(markerCollection);
  }

  // Method to draw and center on a polygon
  void _onPolygonButtonPressed() {
    // Create a marker collection
    final markerCollection = MarkerCollection(
      markerType: MarkerType.polygon,
      name: 'Polygon marker collection',
    );

    // Set coordinates of marker
    final marker = Marker();
    marker.setCoordinates([
      Coordinates(latitude: 52.340234, longitude: 4.886882),
      Coordinates(latitude: 52.300495, longitude: 4.936882),
      Coordinates(latitude: 52.300495, longitude: 4.836882),
    ]);
    markerCollection.add(marker);

    _showMarkerCollectionOnMap(markerCollection);
  }

  // Method to draw and center on points
  void _onPointsButtonPressed() {
    // Create a marker collection
    final markerCollection = MarkerCollection(
      markerType: MarkerType.point,
      name: 'Points marker collection',
    );

    // Set coordinates of marker
    final marker = Marker();
    marker.setCoordinates([
      Coordinates(latitude: 52.380495, longitude: 4.930882),
      Coordinates(latitude: 52.380495, longitude: 4.900882),
      Coordinates(latitude: 52.380495, longitude: 4.870882),
      Coordinates(latitude: 52.380495, longitude: 4.840882),
    ]);
    markerCollection.add(marker);

    _showMarkerCollectionOnMap(markerCollection);
  }

Utility Functions

This utility method clears any previous markers on the map, then displays the new MarkerCollection and centers the map on the area containing the markers.

main.dartView on Github

  Future<void> _showMarkerCollectionOnMap(
    MarkerCollection markerCollection,
  ) async {
    final settings = MarkerCollectionRenderSettings();

    // Clear previous markers from the map
    await _mapController.preferences.markers.clear();

    // Show the current marker on map and center on it
    _mapController.preferences.markers.add(
      markerCollection,
      settings: settings,
    );
    _mapController.centerOnArea(markerCollection.area, zoomLevel: 50);
  }