How to use the Google Maps library with Flutter Web?

Please see the other answer. It is easier than this one!

I was able to get a workable solution, but it isn't pretty. Below is the implementation. If I get some time and a legit port doesn't come a long I will post an example repo.

import 'dart:html';

import 'package:flutter_web/material.dart';
import 'package:lift_ai/base/screen_state.dart';
import 'package:lift_ai/feature/property_common/property_contract.dart';
import 'package:lift_ai/feature/property_common/property_presenter_impl.dart';
import 'package:lift_ai/model/car_status.dart';
import 'package:lift_ai/model/property.dart';
import 'package:flutter_web_ui/ui.dart' as ui;
import 'package:lift_ai/util/widget_util.dart';


class PropertyMapPage extends StatefulWidget {
  final CarStatus carStatus;

  PropertyMapPage(Key key, this.carStatus) : super(key: key);

  @override
  _PropertyMapPageState createState() => _PropertyMapPageState(carStatus);
}

class _PropertyMapPageState extends State<PropertyMapPage>
    implements PropertyListView {
  PropertyPresenter _propertyListPresenter;
  List<Property> properties = [];
  CarStatus carStatus;
  String createdViewId = 'hello-world-html';
  bool inProgress = true;

  _PropertyMapPageState(this.carStatus) {
    _propertyListPresenter = PropertyPresenterImpl(this);
  }

  @override
  void initState() {
    super.initState();
    _propertyListPresenter.getProperties(carStatus, "");
  }

  @override
  void dispose() {
    super.dispose();
    _propertyListPresenter = null;
  }

  @override
  Widget build(BuildContext context) {
    print("Creating html view");

    if (inProgress) {
      return Center(child: CircularProgressIndicator());
    }

    return Row(
      children: <Widget>[
        Container(
            width: MediaQuery.of(context).size.width - 400,
            child: HtmlView(
              viewType: createdViewId,
            )),
        Container(
          width: 400,
          child: properties.isEmpty
              ? WidgetUtil.getEmptyPropertiesView(context)
              : ListView.builder(
                  padding: EdgeInsets.all(8.0),
                  itemCount: properties.length,
                  itemBuilder: (_, index) {
                    return WidgetUtil.buildListRow(
                        context, _propertyListPresenter, properties[index]);
                  },
                ),
        ),
      ],
    );
  }

  @override
  void showProperties(List<Property> properties) {
    String markers = "";

    for (Property property in properties) {
      String marker =
          "var marker = new google.maps.Marker({position: new google.maps.LatLng(${property.lat}, ${property.lng}), map: map, title: 'Hello ${property.id}!'});\n";
      markers += marker;
    }

    String createdViewUpdate = DateTime.now().toString();

    rootBundle.loadString('map.html').then((value) {
      value = value.replaceAll(new RegExp(r'markers'), markers);

      ui.platformViewRegistry.registerViewFactory(
          createdViewId,
          (int viewId) => IFrameElement()
            ..width = (MediaQuery.of(context).size.width - 400).toString()
            ..height = MediaQuery.of(context).size.height.toString()
            ..srcdoc = value
            ..style.border = 'none');
    });

    setState(() {
      inProgress = false;
      this.createdViewId = createdViewUpdate;
      this.properties = properties;
    });
  }

  @override
  void updateScreenState(ScreenState screenState) { }

  @override
  void showException(String string) {
    // TODO: implement showException
  }
}

map.html

<!DOCTYPE html>
<html>
<head>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <title>Simple Markers</title>
    <style>
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 100%;
      }
      /* Optional: Makes the sample page fill the window. */
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
    </style>
</head>
<body>
<div id="map"></div>
<script>

      function initMap() {
        var myLatLng = {lat: 41.850033, lng: -87.6500523};

        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 4,
          center: myLatLng
        });

        markers

      }
    </script>
<script async defer
        src="https://maps.googleapis.com/maps/api/js?key=API_KEY&callback=initMap">
</script>
</body>
</html>

enter image description here

The answer outlined by @panavtec below also works and might have an easier api work work with!

A sample repository of his solution is here:

https://github.com/dazza5000/flutter_web_google_maps_example


If you need to use the library, I found this alternative:

Widget getMap() {
String htmlId = "7";

final mapOptions = new MapOptions()
  ..zoom = 8
  ..center = new LatLng(-34.397, 150.644);

// ignore: undefined_prefixed_name
ui.platformViewRegistry.registerViewFactory(htmlId, (int viewId) {
  final elem = DivElement()
    ..id = htmlId
    ..style.width = "100%"
    ..style.height = "100%"
    ..style.border = 'none';

  new GMap(elem, mapOptions);

  return elem;
});

return HtmlElementView(viewType: htmlId);
}

I didn't tested it thoroughly but it seems to render the map.

A basic working example of this solution is here:

https://github.com/dazza5000/flutter_web_google_maps_example

Created a video walk-through of the project:

https://www.youtube.com/watch?v=iW7pCBL7yWk

Barebones blog article walking through solution:

http://whereisdarran.com/2020/01/google-maps-for-flutter-web/