How to change the icon size of Google Maps marker in Flutter?

Question

I am using google_maps_flutter in my flutter app to use google map I have custom marker icon and I load this with BitmapDescriptor.fromAsset(\"images/car.

Answer 1

Try BitmapDescriptor.fromAssetImage. It will ignore the image size as well.

BitmapDescriptor.fromAssetImage(
            ImageConfiguration(size: Size(32, 32)), 'assets/car.png')
        .then((onValue) {
      setState(() {
        markerIcon = onValue;
      });
    });

Also using default configuration fails.

loadMarkerImage(BuildContext context) {
    var config = createLocalImageConfiguration(context, size: Size(30, 30));
    BitmapDescriptor.fromAssetImage(config, 'assets/car.png')
        .then((onValue) {
      setState(() {
        markerIcon = onValue;
      });
    });
  }

Answer 2

All the answers given are perfect but I noticed that when you set the targetWidth to a specified number then you might have issues with different phones that have a different devicePixelRatio. So this is how I implemented it.

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


  Future<Uint8List> getBytesFromAsset(String path) async {
    double pixelRatio = MediaQuery.of(context).devicePixelRatio;
    ByteData data = await rootBundle.load(path);
    ui.Codec codec = await ui.instantiateImageCodec(
        data.buffer.asUint8List(),
        targetWidth: pixelRatio.round() * 30
    );
    ui.FrameInfo fi = await codec.getNextFrame();
    return (await fi.image.toByteData(format: ui.ImageByteFormat.png)).buffer.asUint8List();
  }

and use the method like this

final Uint8List markerIcon = await getBytesFromAsset('assets/images/bike.png');

Marker(icon: BitmapDescriptor.fromBytes(markerIcon),)

That gives me a dynamic size depending on the devicePixelRatio.

This worked perfectly for me.