Avoid replacing advanced marker content on move

packages/google_maps_flutter/google_maps_flutter_web/example/latest/integration_test/advanced_markers_test.dart

@@ -335,6 +335,72 @@ void main() {
       expect(icon.style.height, '${expectedSize}px');
     });
 
+    testWidgets('changeMarkers preserves bitmap icon content when position changes', (
+      WidgetTester tester,
+    ) async {
+      const markerId = MarkerId('1');
+      final Uint8List bytes = const Base64Decoder().convert(iconImageBase64);
+      final markers = <AdvancedMarker>{
+        AdvancedMarker(
+          markerId: markerId,
+          icon: BytesMapBitmap(bytes, imagePixelRatio: 1),
+          position: const LatLng(1, 2),
+        ),
+      };
+      await controller.addMarkers(markers);
+
+      final gmaps.AdvancedMarkerElement? marker = controller.markers[markerId]?.marker;
+      expect(marker, isNotNull);
+      final icon = marker!.content as HTMLImageElement?;
+      expect(icon, isNotNull);
+      final String blobUrl = icon!.src;
+
+      final updatedMarkers = <AdvancedMarker>{
+        AdvancedMarker(
+          markerId: markerId,
+          icon: BytesMapBitmap(bytes, imagePixelRatio: 1),
+          position: const LatLng(42, 54),
+        ),
+      };
+      await controller.changeMarkers(updatedMarkers);
+
+      final position = marker.position! as gmaps.LatLngLiteral;
+      expect(position.lat, equals(42));
+      expect(position.lng, equals(54));
+      expect(icon.isSameNode(marker.content), isTrue);
+      expect(icon.src, blobUrl);
+    });
+
+    testWidgets('changeMarkers replaces bitmap icon content when alpha changes', (
+      WidgetTester tester,
+    ) async {
+      const markerId = MarkerId('1');
+      final Uint8List bytes = const Base64Decoder().convert(iconImageBase64);
+      final markers = <AdvancedMarker>{
+        AdvancedMarker(markerId: markerId, icon: BytesMapBitmap(bytes, imagePixelRatio: 1)),
+      };
+      await controller.addMarkers(markers);
+
+      final gmaps.AdvancedMarkerElement? marker = controller.markers[markerId]?.marker;
+      expect(marker, isNotNull);
+      final icon = marker!.content as HTMLImageElement?;
+      expect(icon, isNotNull);
+
+      final updatedMarkers = <AdvancedMarker>{
+        AdvancedMarker(
+          markerId: markerId,
+          alpha: 0.5,
+          icon: BytesMapBitmap(bytes, imagePixelRatio: 1),
+        ),
+      };
+      await controller.changeMarkers(updatedMarkers);
+
+      final updatedIcon = marker.content as HTMLImageElement?;
+      expect(updatedIcon, isNotNull);
+      expect(updatedIcon!.isSameNode(icon), isFalse);
+      expect(updatedIcon.style.opacity, '0.5');
+    });
+
     testWidgets('markers with custom bitmap icon and pixel ratio work', (
       WidgetTester tester,
     ) async {

packages/google_maps_flutter/google_maps_flutter_web/lib/src/convert.dart

@@ -689,22 +689,68 @@ Future<gmaps.Icon?> _gmIconFromBitmapDescriptor(
   return icon;
 }
 
+class _AdvancedMarkerContentConfiguration {
+  _AdvancedMarkerContentConfiguration({
+    required this.alpha,
+    required this.visible,
+    required this.rotation,
+    required this.iconHash,
+  });
+
+  factory _AdvancedMarkerContentConfiguration.fromMarker(AdvancedMarker marker) {
+    return _AdvancedMarkerContentConfiguration(
+      alpha: marker.alpha,
+      visible: marker.visible,
+      rotation: marker.rotation,
+      iconHash: const DeepCollectionEquality().hash(marker.icon.toJson()),
+    );
+  }
+
+  final double alpha;
+  final bool visible;
+  final double rotation;
+  final int iconHash;
+
+  bool isMatchFor(AdvancedMarker marker) {
+    return alpha == marker.alpha &&
+        visible == marker.visible &&
+        rotation == marker.rotation &&
+        iconHash == const DeepCollectionEquality().hash(marker.icon.toJson());
+  }
+}
+
+bool _isAdvancedMarkerContentUpdateRequired(
+  Marker marker,
+  _AdvancedMarkerContentConfiguration? previousConfiguration,
+) {
+  if (marker is! AdvancedMarker || previousConfiguration == null) {
+    return true;
+  }
+  return !previousConfiguration.isMatchFor(marker);
+}
+
 // Computes the options for a new [gmaps.Marker] from an incoming set of options
 // [marker], and the existing marker registered with the map: [currentMarker].
-Future<O> _markerOptionsFromMarker<T, O>(Marker marker, T? currentMarker) async {
+Future<O> _markerOptionsFromMarker<T, O>(
+  Marker marker,
+  T? currentMarker, {
+  bool isAdvancedMarkerContentUpdateRequired = true,
+}) async {
   if (marker is AdvancedMarker) {
     final options = gmaps.AdvancedMarkerElementOptions()
       ..collisionBehavior = _markerCollisionBehaviorToGmCollisionBehavior(marker.collisionBehavior)
-      ..content = await _advancedMarkerIconFromBitmapDescriptor(
-        marker.icon,
-        opacity: marker.alpha,
-        isVisible: marker.visible,
-        rotation: marker.rotation,
-      )
       ..position = gmaps.LatLng(marker.position.latitude, marker.position.longitude)
       ..title = sanitizeHtml(marker.infoWindow.title ?? '')
       ..zIndex = marker.zIndex
       ..gmpDraggable = marker.draggable;
+    if (isAdvancedMarkerContentUpdateRequired) {
+      options.content = await _advancedMarkerIconFromBitmapDescriptor(
+        marker.icon,
+        opacity: marker.alpha,
+        isVisible: marker.visible,
+        rotation: marker.rotation,
+      );
+    }
     return options as O;
   } else {
     final options = gmaps.MarkerOptions()

packages/google_maps_flutter/google_maps_flutter_web/lib/src/marker.dart

@@ -67,7 +67,11 @@ abstract class MarkerController<T, O> {
   /// Updates the options of the wrapped marker object.
   ///
   /// This cannot be called after [remove].
-  void update(O options, {web.HTMLElement? newInfoWindowContent});
+  void update(
+    O options, {
+    bool isContentUpdateRequired = true,
+    web.HTMLElement? newInfoWindowContent,
+  });
 
   /// Initializes the listener for the wrapped marker object.
   void addMarkerListener({
@@ -193,7 +197,11 @@ class LegacyMarkerController extends MarkerController<gmaps.Marker, gmaps.Marker
   }
 
   @override
-  void update(gmaps.MarkerOptions options, {web.HTMLElement? newInfoWindowContent}) {
+  void update(
+    gmaps.MarkerOptions options, {
+    bool isContentUpdateRequired = true,
+    web.HTMLElement? newInfoWindowContent,
+  }) {
     assert(_marker != null, 'Cannot `update` Marker after calling `remove`.');
     _marker!.options = options;
 
@@ -302,12 +310,18 @@ class AdvancedMarkerController
   }
 
   @override
-  void update(gmaps.AdvancedMarkerElementOptions options, {web.HTMLElement? newInfoWindowContent}) {
+  void update(
+    gmaps.AdvancedMarkerElementOptions options, {
+    bool isContentUpdateRequired = true,
+    web.HTMLElement? newInfoWindowContent,
+  }) {
     assert(_marker != null, 'Cannot `update` Marker after calling `remove`.');
 
     final gmaps.AdvancedMarkerElement marker = _marker!;
     marker.collisionBehavior = options.collisionBehavior;
-    marker.content = options.content;
+    if (isContentUpdateRequired) {
+      marker.content = options.content;
+    }
     marker.gmpDraggable = options.gmpDraggable;
     marker.position = options.position;
     marker.title = options.title ?? '';

packages/google_maps_flutter/google_maps_flutter_web/lib/src/markers.dart

@@ -30,6 +30,10 @@ abstract class MarkersController<T extends Object, O> extends GeometryController
   // A cache of [MarkerController]s indexed by their [MarkerId].
   final Map<MarkerId, MarkerController<T, O>> _markerIdToController;
 
+  // A cache of the advanced marker content configuration indexed by [MarkerId].
+  final Map<MarkerId, _AdvancedMarkerContentConfiguration> _contentConfigurationByMarkerId =
+      <MarkerId, _AdvancedMarkerContentConfiguration>{};
+
   // The stream over which markers broadcast their events
   final StreamController<MapEvent<Object?>> _streamController;
 
@@ -103,6 +107,7 @@ abstract class MarkersController<T extends Object, O> extends GeometryController
       gmInfoWindow,
     );
     _markerIdToController[marker.markerId] = controller;
+    _updateAdvancedMarkerContentConfiguration(marker);
 
     return controller;
   }
@@ -136,16 +141,37 @@ abstract class MarkersController<T extends Object, O> extends GeometryController
         _removeMarker(marker.markerId);
         await _addMarker(marker);
       } else {
-        final O markerOptions = await _markerOptionsFromMarker(marker, markerController.marker);
+        final _AdvancedMarkerContentConfiguration? previousContentConfiguration =
+            _contentConfigurationByMarkerId[marker.markerId];
+        final bool isAdvancedMarkerContentUpdateRequired = _isAdvancedMarkerContentUpdateRequired(
+          marker,
+          previousContentConfiguration,
+        );
+        final O markerOptions = await _markerOptionsFromMarker(
+          marker,
+          markerController.marker,
+          isAdvancedMarkerContentUpdateRequired: isAdvancedMarkerContentUpdateRequired,
+        );
         final gmaps.InfoWindowOptions? infoWindow = _infoWindowOptionsFromMarker(marker);
         markerController.update(
           markerOptions,
+          isContentUpdateRequired: isAdvancedMarkerContentUpdateRequired,
           newInfoWindowContent: infoWindow?.content as web.HTMLElement?,
         );
+        _updateAdvancedMarkerContentConfiguration(marker);
       }
     }
   }
 
+  void _updateAdvancedMarkerContentConfiguration(Marker marker) {
+    if (marker is AdvancedMarker) {
+      _contentConfigurationByMarkerId[marker.markerId] =
+          _AdvancedMarkerContentConfiguration.fromMarker(marker);
+    } else {
+      _contentConfigurationByMarkerId.remove(marker.markerId);
+    }
+  }
+
   /// Removes a set of [MarkerId]s from the cache.
   void removeMarkers(Set<MarkerId> markerIdsToRemove) {
     final List<MapEntry<MarkerId, MarkerController<T, O>?>> markersControllers = markerIdsToRemove
@@ -182,6 +208,7 @@ abstract class MarkersController<T extends Object, O> extends GeometryController
     for (final markerController in markersControllers) {
       markerController.value?.remove();
       _markerIdToController.remove(markerController.key);
+      _contentConfigurationByMarkerId.remove(markerController.key);
     }
   }
 
@@ -195,6 +222,7 @@ abstract class MarkersController<T extends Object, O> extends GeometryController
     }
     markerController?.remove();
     _markerIdToController.remove(markerId);
+    _contentConfigurationByMarkerId.remove(markerId);
   }
 
   // InfoWindow...