mapScreen.dart

  //******* getMarkers */
  Future<Uint8List> getBytesFromAsset(String path, int width) async {
    ByteData data = await rootBundle.load(path);
    ui.Codec codec = await ui.instantiateImageCodec(data.buffer.asUint8List(),
        targetWidth: width);
    ui.FrameInfo fi = await codec.getNextFrame();
    return (await fi.image.toByteData(format: ui.ImageByteFormat.png))
        .buffer
        .asUint8List();
  }

  void getMarkers() async {
    final Uint8List userMarkerIcon =
        await getBytesFromAsset('assets/normalMarker.png', 75);

    final Uint8List selectedMarkerIcon =
        await getBytesFromAsset('assets/selectedMarker.png', 100);

    markers = {};

    Tools.markersList.forEach((element) {
      if (element.latitude != null && element.longitude != null) {
        if (element.id == indexMarker) {
          markers.add(Marker(
              draggable: false,
              markerId: MarkerId(element.latitude + element.longitude),
              position: LatLng(
                double.tryParse(element.latitude),
                double.tryParse(element.longitude),
              ),
              icon: BitmapDescriptor.fromBytes(selectedMarkerIcon),
              infoWindow: InfoWindow(title: element.name)));
        } else {
          markers.add(Marker(
              draggable: false,
              markerId: MarkerId(element.latitude + element.longitude),
              position: LatLng(
                double.tryParse(element.latitude),
                double.tryParse(element.longitude),
              ),
              icon: BitmapDescriptor.fromBytes(userMarkerIcon),
              infoWindow: InfoWindow(title: element.name)));
        }
      }
    });

    valueNotifier.value = indexMarker; // we will need it soon 
  }