How to Add Custom Markers on Google Maps in Flutter?

import 'package:flutter/material.dart';
import 'package:google_maps/Convert_Lat_Long.dart';
import 'package:google_maps/HomePage.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'GFG',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.green,
      ),
      // First screen of our app
      home: const HomePage(),
    );
  }
}

import 'dart:async';
import 'dart:typed_data';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:geolocator/geolocator.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {

  // created controller for displaying Google Maps
  Completer<GoogleMapController> _controller = Completer();

  // given camera position 
  static final CameraPosition _kGoogle = const CameraPosition(
      target: LatLng(19.0759837, 72.8776559),
    zoom: 15,
  );

  Uint8List? marketimages;
  List<String> images = ['images/car.png','images/bus.png', 'images/travelling.png', 'images/bycicle.png', 'images/food-delivery.png'];

  // created empty list of markers
  final List<Marker> _markers = <Marker>[];
  
  // created list of coordinates of various locations
  final List<LatLng> _latLen = <LatLng>[

    LatLng(19.0759837, 72.8776559),
    LatLng(28.679079, 77.069710),
    LatLng(26.850000, 80.949997),
    LatLng(24.879999, 74.629997),
    LatLng(16.166700, 74.833298),
    LatLng(12.971599, 77.594563),
  ];

  // declared method to get Images
  Future<Uint8List> getImages(String path, int width) async{
    ByteData data = await rootBundle.load(path);
    ui.Codec codec = await ui.instantiateImageCodec(data.buffer.asUint8List(), targetHeight: width);
    ui.FrameInfo fi = await codec.getNextFrame();
    return(await fi.image.toByteData(format: ui.ImageByteFormat.png))!.buffer.asUint8List();

  }
  
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    // initialize loadData method
    loadData();
  }

  // created method for displaying custom markers according to index 
  loadData() async{
    for(int i=0 ;i<images.length; i++){
      final Uint8List markIcons = await getImages(images[i], 100);
      // makers added according to index
      _markers.add(
        Marker(
          // given marker id
          markerId: MarkerId(i.toString()),
          // given marker icon
          icon: BitmapDescriptor.fromBytes(markIcons),
          // given position
          position: _latLen[i],
          infoWindow: InfoWindow(
            // given title for marker
            title: 'Location: '+i.toString(),
          ),
        )
      );
      setState(() {
      });
    }
  }
  
 @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Color(0xFF0F9D58),
        // on below line we have given title of app
        title: Text("GFG"),
      ),
      body: Container(
        child: SafeArea(
          child: GoogleMap(
            // given camera position
              initialCameraPosition: _kGoogle,
            // set markers on google map
            markers: Set<Marker>.of(_markers),
            // on below line we have given map type 
            mapType: MapType.normal,
            // on below line we have enabled location
            myLocationEnabled: true,
            myLocationButtonEnabled: true,
            // on below line we have enabled compass 
            compassEnabled: true,
            // below line displays google map in our app
            onMapCreated: (GoogleMapController controller){
                _controller.complete(controller);
            },
          ),
        ),
      ),
    );
  }
}