CODE EXAMPLE FOR DART

custom marker google maps flutter

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();
  }
 
 // init marker icon 
 
  final Uint8List markerIcon2 =
        await getBytesFromAsset('assets/images/m1.png', 99);
    final Uint8List markerIcon1 =
        await getBytesFromAsset('assets/images/camion.png', 139);
        
    teste1 = BitmapDescriptor.fromBytes(markerIcon2);
    teste2 = BitmapDescriptor.fromBytes(markerIcon1);
    
  // show marker 
    Marker(icon: teste1)
    Marker(icon: teste2)