Worked on platform interface

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/method_channel/method_channel_google_maps_flutter.dart

@@ -324,6 +324,18 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
     );
   }
 
+  @override
+  Future<void> updateHeatmapLayers(
+    HeatmapLayerUpdates heatmapLayerUpdates, {
+    required int mapId,
+  }) {
+    assert(heatmapLayerUpdates != null);
+    return channel(mapId).invokeMethod<void>(
+      'heatmapLayers#update',
+      heatmapLayerUpdates.toJson(),
+    );
+  }
+
   @override
   Future<void> updateTileOverlays({
     required Set<TileOverlay> newTileOverlays,
@@ -490,6 +502,7 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
     Set<Polygon> polygons = const <Polygon>{},
     Set<Polyline> polylines = const <Polyline>{},
     Set<Circle> circles = const <Circle>{},
+    Set<HeatmapLayer> heatmapLayers = const <HeatmapLayer>{},
     Set<TileOverlay> tileOverlays = const <TileOverlay>{},
     Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers,
     Map<String, dynamic> mapOptions = const <String, dynamic>{},
@@ -501,6 +514,7 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
       'polygonsToAdd': serializePolygonSet(polygons),
       'polylinesToAdd': serializePolylineSet(polylines),
       'circlesToAdd': serializeCircleSet(circles),
+      'heatmapLayersToAdd': serializeHeatmapLayerSet(heatmapLayers),
       'tileOverlaysToAdd': serializeTileOverlaySet(tileOverlays),
     };
 
@@ -572,6 +586,7 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
     Set<Polygon> polygons = const <Polygon>{},
     Set<Polyline> polylines = const <Polyline>{},
     Set<Circle> circles = const <Circle>{},
+    Set<HeatmapLayer> heatmapLayers = const <HeatmapLayer>{},
     Set<TileOverlay> tileOverlays = const <TileOverlay>{},
     Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers,
     Map<String, dynamic> mapOptions = const <String, dynamic>{},
@@ -585,6 +600,7 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
       polygons: polygons,
       polylines: polylines,
       circles: circles,
+      heatmapLayers: heatmapLayers,
       tileOverlays: tileOverlays,
       gestureRecognizers: gestureRecognizers,
       mapOptions: mapOptions,

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/platform_interface/google_maps_flutter_platform.dart

@@ -115,6 +115,19 @@ abstract class GoogleMapsFlutterPlatform extends PlatformInterface {
     throw UnimplementedError('updateCircles() has not been implemented.');
   }
 
+  /// Updates heatmap layer configuration.
+  ///
+  /// Change listeners are notified once the update has been made on the
+  /// platform side.
+  ///
+  /// The returned [Future] completes after listeners have been notified.
+  Future<void> updateHeatmapLayers(
+    HeatmapLayerUpdates heatmapLayerUpdates, {
+    required int mapId,
+  }) {
+    throw UnimplementedError('updateHeatmapLayers() has not been implemented.');
+  }
+
   /// Updates tile overlay configuration.
   ///
   /// Change listeners are notified once the update has been made on the
@@ -357,6 +370,7 @@ abstract class GoogleMapsFlutterPlatform extends PlatformInterface {
     Set<Polygon> polygons = const <Polygon>{},
     Set<Polyline> polylines = const <Polyline>{},
     Set<Circle> circles = const <Circle>{},
+    Set<HeatmapLayer> heatmapLayers = const <HeatmapLayer>{},
     Set<TileOverlay> tileOverlays = const <TileOverlay>{},
     Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers =
         const <Factory<OneSequenceGestureRecognizer>>{},
@@ -385,6 +399,7 @@ abstract class GoogleMapsFlutterPlatform extends PlatformInterface {
     Set<Polygon> polygons = const <Polygon>{},
     Set<Polyline> polylines = const <Polyline>{},
     Set<Circle> circles = const <Circle>{},
+    Set<HeatmapLayer> heatmapLayers = const <HeatmapLayer>{},
     Set<TileOverlay> tileOverlays = const <TileOverlay>{},
     Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers,
     Map<String, dynamic> mapOptions = const <String, dynamic>{},
@@ -397,6 +412,7 @@ abstract class GoogleMapsFlutterPlatform extends PlatformInterface {
       polygons: polygons,
       polylines: polylines,
       circles: circles,
+      heatmapLayers: heatmapLayers,
       tileOverlays: tileOverlays,
       gestureRecognizers: gestureRecognizers,
       mapOptions: mapOptions,

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/types/heatmap_layer.dart

@@ -0,0 +1,128 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart' show listEquals;
+import 'package:flutter/material.dart' show Color;
+import 'package:flutter/foundation.dart' show immutable;
+
+import 'types.dart';
+
+/// Uniquely identifies a [HeatmapLayer] among [GoogleMap] heatmap layers.
+///
+/// This does not have to be globally unique, only unique among the list.
+@immutable
+class HeatmapLayerId extends MapsObjectId<HeatmapLayer> {
+  /// Creates an immutable identifier for a [HeatmapLayer].
+  const HeatmapLayerId(String value) : super(value);
+}
+
+/// Draws a heatmap layer on the map.
+@immutable
+class HeatmapLayer implements MapsObject<HeatmapLayer> {
+  /// Creates an immutable representation of a [HeatmapLayer] to draw on
+  /// [GoogleMap].
+  const HeatmapLayer({
+    required this.heatmapLayerId,
+    this.data = const [],
+    this.dissipating = true,
+    this.gradient,
+    this.maxIntensity,
+    this.opacity = 0.6,
+    this.radius,
+  });
+
+  /// Uniquely identifies a [HeatmapLayer].
+  final HeatmapLayerId heatmapLayerId;
+
+  @override
+  HeatmapLayerId get mapsId => heatmapLayerId;
+
+  /// The data points to display.
+  final List<WeightedLatLng> data;
+
+  /// Specifies whether heatmaps dissipate on zoom. By default, the radius of
+  /// influence of a data point is specified by the radius option only. When
+  /// dissipating is disabled, the radius option is interpreted as a radius at
+  /// zoom level 0.
+  final bool dissipating;
+
+  /// The color gradient of the heatmap
+  final List<Color>? gradient;
+
+  /// The maximum intensity of the heatmap. By default, heatmap colors are
+  /// dynamically scaled according to the greatest concentration of points at
+  /// any particular pixel on the map. This property allows you to specify a
+  /// fixed maximum.
+  final double? maxIntensity;
+
+  /// The opacity of the heatmap, expressed as a number between 0 and 1.
+  /// Defaults to 0.6.
+  final double opacity;
+
+  /// The radius of influence for each data point, in pixels.
+  final double? radius;
+
+  /// Creates a new [HeatmapLayer] object whose values are the same as this
+  /// instance, unless overwritten by the specified parameters.
+  HeatmapLayer copyWith({
+    List<WeightedLatLng>? dataParam,
+    bool? dissipatingParam,
+    List<Color>? gradientParam,
+    double? maxIntensityParam,
+    double? opacityParam,
+    double? radiusParam,
+  }) {
+    return HeatmapLayer(
+      heatmapLayerId: heatmapLayerId,
+      data: dataParam ?? data,
+      dissipating: dissipatingParam ?? dissipating,
+      gradient: gradientParam ?? gradient,
+      maxIntensity: maxIntensityParam ?? maxIntensity,
+      opacity: opacityParam ?? opacity,
+      radius: radiusParam ?? radius,
+    );
+  }
+
+  /// Creates a new [HeatmapLayer] object whose values are the same as this
+  /// instance.
+  HeatmapLayer clone() => copyWith();
+
+  /// Converts this object to something serializable in JSON.
+  Object toJson() {
+    final Map<String, Object> json = <String, Object>{};
+
+    void addIfPresent(String fieldName, Object? value) {
+      if (value != null) {
+        json[fieldName] = value;
+      }
+    }
+
+    addIfPresent('heatmapLayerId', heatmapLayerId.value);
+    addIfPresent('data', data.map((e) => e.toJson()));
+    addIfPresent('dissipating', dissipating);
+    addIfPresent('gradient', gradient?.map((e) => e.value));
+    addIfPresent('maxIntensity', maxIntensity);
+    addIfPresent('opacity', opacity);
+    addIfPresent('radius', radius);
+
+    return json;
+  }
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) return true;
+    if (other.runtimeType != runtimeType) return false;
+    final HeatmapLayer typedOther = other as HeatmapLayer;
+    return heatmapLayerId == typedOther.heatmapLayerId &&
+        listEquals(data, typedOther.data) &&
+        dissipating == typedOther.dissipating &&
+        listEquals(gradient, typedOther.gradient) &&
+        maxIntensity == typedOther.maxIntensity &&
+        opacity == typedOther.opacity &&
+        radius == typedOther.radius;
+  }
+
+  @override
+  int get hashCode => heatmapLayerId.hashCode;
+}

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/types/heatmap_layer_updates.dart

@@ -0,0 +1,27 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'types.dart';
+
+/// [HeatmapLayer] update events to be applied to the [GoogleMap].
+///
+/// Used in [GoogleMapController] when the map is updated.
+// (Do not re-export)
+class HeatmapLayerUpdates extends MapsObjectUpdates<HeatmapLayer> {
+  /// Computes [HeatmapLayerUpdates] given previous and current [HeatmapLayer]s.
+  HeatmapLayerUpdates.from(
+    Set<HeatmapLayer> previous,
+    Set<HeatmapLayer> current,
+  ) : super.from(previous, current, objectName: 'heatmapLayer');
+
+  /// Set of HeatmapLayers to be added in this update.
+  Set<HeatmapLayer> get heatmapLayersToAdd => objectsToAdd;
+
+  /// Set of HeatmapLayers to be removed in this update.
+  Set<HeatmapLayerId> get heatmapLayerIdsToRemove =>
+      objectIdsToRemove.cast<HeatmapLayerId>();
+
+  /// Set of HeatmapLayers to be changed in this update.
+  Set<HeatmapLayer> get heatmapLayersToChange => objectsToChange;
+}

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/types/location.dart

@@ -132,3 +132,45 @@ class LatLngBounds {
   @override
   int get hashCode => Object.hash(southwest, northeast);
 }
+
+/// A data point entry for a heatmap.
+/// This is a geographical data point with a weight attribute.
+class WeightedLatLng {
+  /// The location of the data point.
+  final LatLng location;
+
+  /// The weighting value of the data point.
+  final double weight;
+
+  /// Creates a [WeightedLatLng] with the specified [weight]
+  WeightedLatLng(this.location, {this.weight = 1.0});
+
+  /// Converts this object to something serializable in JSON.
+  Object toJson() {
+    return <Object>[location.toJson(), weight];
+  }
+
+  /// Initialize a [WeightedLatLng] from an \[location, weight\] array.
+  static WeightedLatLng? fromJson(Object? json) {
+    if (json == null) {
+      return null;
+    }
+    assert(json is List && json.length == 2);
+    final list = json as List;
+    return WeightedLatLng(
+      LatLng.fromJson(list[0])!,
+      weight: list[1],
+    );
+  }
+
+  @override
+  String toString() => '$runtimeType($location, $weight)';
+
+  @override
+  bool operator ==(Object o) {
+    return o is WeightedLatLng && o.location == location && o.weight == weight;
+  }
+
+  @override
+  int get hashCode => Object.hash(location, weight);
+}

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/types/types.dart

@@ -9,6 +9,8 @@ export 'camera.dart';
 export 'cap.dart';
 export 'circle_updates.dart';
 export 'circle.dart';
+export 'heatmap_layer_updates.dart';
+export 'heatmap_layer.dart';
 export 'joint_type.dart';
 export 'location.dart';
 export 'maps_object_updates.dart';
@@ -28,6 +30,7 @@ export 'ui.dart';
 
 // Export the utils, they're used by the Widget
 export 'utils/circle.dart';
+export 'utils/heatmap_layer.dart';
 export 'utils/marker.dart';
 export 'utils/polygon.dart';
 export 'utils/polyline.dart';

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/types/utils/heatmap_layer.dart

@@ -0,0 +1,20 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../types.dart';
+import 'maps_object.dart';
+
+/// Converts an [Iterable] of HeatmapLayers in a Map of
+/// HeatmapLayerId -> HeatmapLayer.
+Map<HeatmapLayerId, HeatmapLayer> keyByHeatmapLayerId(
+  Iterable<HeatmapLayer> heatmapLayers,
+) {
+  return keyByMapsObjectId<HeatmapLayer>(heatmapLayers)
+      .cast<HeatmapLayerId, HeatmapLayer>();
+}
+
+/// Converts a Set of HeatmapLayers into something serializable in JSON.
+Object serializeHeatmapLayerSet(Set<HeatmapLayer> heatmapLayers) {
+  return serializeMapsObjectSet(heatmapLayers);
+}

packages/google_maps_flutter/google_maps_flutter_platform_interface/test/platform_interface/google_maps_flutter_platform_test.dart

@@ -80,6 +80,7 @@ class BuildViewGoogleMapsFlutterPlatform extends GoogleMapsFlutterPlatform {
     Set<Polygon> polygons = const <Polygon>{},
     Set<Polyline> polylines = const <Polyline>{},
     Set<Circle> circles = const <Circle>{},
+    Set<HeatmapLayer> heatmapLayers = const <HeatmapLayer>{},
     Set<TileOverlay> tileOverlays = const <TileOverlay>{},
     Set<Factory<OneSequenceGestureRecognizer>>? gestureRecognizers =
         const <Factory<OneSequenceGestureRecognizer>>{},