我在我的应用程序中使用了 google_maps_flutter: ^2.0.6 包。在这里，我使用提供程序将标记加载到我的应用程序中。 此外，我需要在点击时更改标记的装饰图像。问题是我的 ontap 事件正在执行，但图像没有改变。

下面是谷歌地图小部件的代码

  Set<Marker> customMarkers = Set<Marker>();

  @override
  void initState() {
    super.initState();
    getMarkers();
  }

  void getMarkers() {
    Future.delayed(const Duration(seconds: 2),() {
      setState(() {
        customMarkers =
            Provider.of<MapProvider>(context,listen: false).getMarkers();
      });
    });
  }

  void _onmapCreated(GoogleMapController controller) {
    mapController = controller;
  }

  @override
  Widget build(BuildContext context) {
    var con = config.SizeConfig();
    return Scaffold(
      body: Container(
        height: con.h(),width: con.w(),child: Stack(
          children: [
            GoogleMap(
              zoomControlsEnabled: false,mapType: MapType.normal,onmapCreated: (controller) {
                _onmapCreated(controller);                
              },markers: customMarkers,initialCameraPosition: CameraPosition(
                target: _center,zoom: 14.0,),BackBtn(con: con),TitleWidget(con: con),BottomBtn(con: con),],);
  }

下面是我创建的提供者

  class MapProvider extends ChangeNotifier {
  Set<Marker> customMarkers = Set<Marker>();


  void generateMarkers(context) {
    var con = config.SizeConfig();

    var locations = [
      LatLng(56.9570879,24.1014793),LatLng(56.9568659,24.0961793),LatLng(56.9546749,24.0836303),LatLng(56.9408639,24.1005883),LatLng(56.9420809,24.0958893)
    ];

    var markerListLength = 5;

    Future.delayed(const Duration(seconds: 2),() {
      var decorationImageDarkBlue = DecorationImage(
          image: AssetImage('${Constants.IMAGE_PATH}icon-map-pin.png'),fit: BoxFit.scaleDown);

      var decorationImageGreen = DecorationImage(
          image: AssetImage('${Constants.IMAGE_PATH}icon-map-pin-green.png'),fit: BoxFit.scaleDown);

      var decorationImageLightBlue = DecorationImage(
          image:
              AssetImage('${Constants.IMAGE_PATH}icon-map-pin-light-blue.png'),fit: BoxFit.scaleDown);

      var decorationImageBlack = DecorationImage(
          image: AssetImage('${Constants.IMAGE_PATH}icon-map-pin-black.png'),fit: BoxFit.scaleDown);

      for (var i = 0; i < markerListLength; i++) {
        var selected = i == 0
            ? decorationImageDarkBlue
            : i == 1
                ? decorationImageGreen
                : decorationImageLightBlue;

        MarkerGenerator(
          [
            Container(
              alignment: Alignment.topCenter,padding: EdgeInsets.all(con.initWidth(v1: 6)),decoration: BoxDecoration(image: selected),height: con.initHeight(v1: 40),width: con.initWidth(v1: 30.47),child: Container(
                  width: con.initWidth(v1: 18),height: con.initWidth(v1: 18),alignment: Alignment.center,decoration:
                      BoxDecoration(color: kwhite,shape: BoxShape.circle),child: CustomText(
                      fontColor: Color(0xFF1879D3),fontSize: 12,text: '$i')),)
          ],(bitmaps) {
            customMarkers.add(Marker(
                infoWindow: InfoWindow(title: "$i"),markerId: new MarkerId("randomText$i"),position: locations[i],icon: BitmapDescriptor.fromBytes(bitmaps.first),anchor: Offset(0.5,0.5),onTap: () {
                  print("marker on tap executed"); // this line prints
                  selected = decorationImageBlack; //this line isn't
                  notifyListeners();
                }));
          },).generate(context);
      }
    });
  }

  Set<Marker> getMarkers() {
    return customMarkers;
  }
}

这里的错误是什么，我该如何解决。