您可以尝试此解决方案：

static GoogleMapController? mapController;
  int zoomLevel = 3;
  double zoomRadius = 400000; 
  Future<void> getNewRadius() async {
    double zoomvalue = await mapController!.getZoomLevel(); //this will get your zoom level
    int zoomLevel = zoomvalue.toInt();
    if (zoomLevel < 4 && zoomLevel != zoomLevel) {
      zoomLevel = zoomLevel;
      zoomRadius = 400000;
      setState(() {});
    } else if (zoomLevel > zoomLevel) {
      int factor = zoomLevel - zoomLevel;
      zoomLevel = zoomLevel;
      zoomRadius = zoomRadius / (2 * factor);
      setState(() {});
    } else if (zoomLevel < zoomLevel) {
      int factor = zoomLevel - zoomLevel;
      zoomLevel = zoomLevel;
      zoomRadius = zoomRadius * (2 * factor);
      setState(() {});
    }
  }

  // here we're calling the method on zoom in and zoom out of the map so that we can dynamically update the value
  void _onCameraMove(CameraPosition position) async {
    try {
      await radius();
    } catch (_) {}
  }

  void _onMapCreated(GoogleMapController mapController) {
    GoogleMapPageState.mapController = mapController;
  }