correcao de erros no codigo do mapa

lib/screens/google_map_screen.dart

@@ -18,11 +18,14 @@ class _GoogleMapScreenState extends State<GoogleMapScreen> {
   GoogleMapController? _mapController;
   StreamSubscription<Position>? _positionStreamSubscription;
   Timer? _simulationTimer;
-  
+
+  // Controle de frequência de atualização para evitar sobrecarga e crashes
+  DateTime? _lastUpdate;
+
   final List<LatLng> _routePoints = [];
   final Set<Polyline> _polylines = {};
   final Set<Marker> _markers = {};
-  
+
   LatLng? _plannedStart;
   LatLng? _plannedEnd;
   bool _isPlanningMode = false;
@@ -44,6 +47,7 @@ class _GoogleMapScreenState extends State<GoogleMapScreen> {
   }
 
   Future<void> _setupIconsAndTracking() async {
+    // Marcadores premium: tamanho ideal para visibilidade e estética
     _startIcon = await _createPremiumMarker(Colors.greenAccent, Icons.play_arrow_rounded, 85);
     _finishIcon = await _createPremiumMarker(AppColors.coral, Icons.flag_rounded, 85);
     _arrowIcon = await _createArrowMarker(Colors.black, Colors.white, 95);
@@ -87,6 +91,7 @@ class _GoogleMapScreenState extends State<GoogleMapScreen> {
   void dispose() {
     _positionStreamSubscription?.cancel();
     _simulationTimer?.cancel();
+    _mapController?.dispose();
     super.dispose();
   }
 
@@ -98,45 +103,48 @@ class _GoogleMapScreenState extends State<GoogleMapScreen> {
       permission = await Geolocator.requestPermission();
       if (permission == LocationPermission.denied) return;
     }
-    Position position = await Geolocator.getCurrentPosition();
+    Position position = await Geolocator.getCurrentPosition(desiredAccuracy: LocationAccuracy.bestForNavigation);
     _currentPosition = LatLng(position.latitude, position.longitude);
     setState(() => _isLoading = false);
     _startLocationStream();
   }
 
   void _startLocationStream() {
-    _positionStreamSubscription = Geolocator.getPositionStream(locationSettings: const LocationSettings(accuracy: LocationAccuracy.high, distanceFilter: 5)).listen((Position position) {
-      if (!_isSimulating) _updatePosition(LatLng(position.latitude, position.longitude), position.speed);
+    _positionStreamSubscription = Geolocator.getPositionStream(
+        locationSettings: const LocationSettings(
+            accuracy: LocationAccuracy.bestForNavigation,
+            distanceFilter: 0
+        )
+    ).listen((Position position) {
+      if (!_isSimulating) {
+        final now = DateTime.now();
+        if (_lastUpdate == null || now.difference(_lastUpdate!).inMilliseconds > 500) {
+          _lastUpdate = now;
+          _updatePosition(LatLng(position.latitude, position.longitude), position.speed);
+        }
+      }
+    }, onError: (error) {
+      debugPrint("Erro no GPS: $error");
     });
   }
 
   void _updatePosition(LatLng newPoint, double speed) {
+    if (!mounted) return;
     setState(() {
       if (_routePoints.isNotEmpty) {
         _totalDistance += Geolocator.distanceBetween(_currentPosition.latitude, _currentPosition.longitude, newPoint.latitude, newPoint.longitude);
       }
-      _currentSpeed = speed;
+      _currentSpeed = speed >= 0 ? speed : 0;
       _routePoints.add(newPoint);
       _currentPosition = newPoint;
-      
-      // Update only the dynamic follower arrow
-      _markers.removeWhere((m) => m.markerId.value == 'follower');
-      _markers.add(Marker(
-        markerId: const MarkerId('follower'),
-        position: _currentPosition,
-        rotation: _calculateRotation(_routePoints),
-        flat: true,
-        anchor: const Offset(0.5, 0.5),
-        icon: _arrowIcon ?? BitmapDescriptor.defaultMarker,
-        zIndex: 12,
-      ));
+      _updateMarkers(); // Agora só atualiza a seta seguidora
 
       if (_routePoints.length > 1) {
         _polylines.removeWhere((p) => p.polylineId.value == 'route' || p.polylineId.value == 'route_glow');
         _polylines.add(Polyline(
           polylineId: const PolylineId('route_glow'),
           points: List.from(_routePoints),
-          color: Colors.lightBlueAccent.withOpacity(0.3),
+          color: Colors.cyanAccent.withOpacity(0.3),
           width: 14,
           zIndex: 9,
         ));
@@ -151,7 +159,25 @@ class _GoogleMapScreenState extends State<GoogleMapScreen> {
         ));
       }
     });
-    _mapController?.animateCamera(CameraUpdate.newLatLng(newPoint));
+
+    if (_mapController != null) {
+      _mapController!.animateCamera(CameraUpdate.newLatLng(newPoint));
+    }
+  }
+
+  void _updateMarkers() {
+    // Remove APENAS o marcador da seta seguidora para evitar duplicidade com o ponto de partida fixo
+    _markers.removeWhere((m) => m.markerId.value == 'follower');
+
+    _markers.add(Marker(
+      markerId: const MarkerId('follower'),
+      position: _currentPosition,
+      rotation: _calculateRotation(_routePoints),
+      flat: true,
+      anchor: const Offset(0.5, 0.5),
+      icon: _arrowIcon ?? BitmapDescriptor.defaultMarker,
+      zIndex: 12,
+    ));
   }
 
   double _calculateRotation(List<LatLng> points) {
@@ -192,40 +218,28 @@ class _GoogleMapScreenState extends State<GoogleMapScreen> {
         _routePoints.clear();
         _polylines.removeWhere((p) => p.polylineId.value == 'route' || p.polylineId.value == 'route_glow');
         _totalDistance = 0.0;
-        
-        // Start from planned start OR current real location
         _currentPosition = _plannedStart ?? _currentPosition;
-        
-        // Initialize routePoints with the start so the arrow appears immediately at the start point
         _routePoints.add(_currentPosition);
-        
-        // Update only the follower arrow. Planned markers are already in the set.
-        _markers.removeWhere((m) => m.markerId.value == 'follower');
-        _markers.add(Marker(
-          markerId: const MarkerId('follower'),
-          position: _currentPosition,
-          flat: true,
-          anchor: const Offset(0.5, 0.5),
-          icon: _arrowIcon ?? BitmapDescriptor.defaultMarker,
-          zIndex: 12,
-        ));
+        _updateMarkers(); // Reposiciona a seta no início
       });
 
-      _simulationTimer = Timer.periodic(const Duration(seconds: 1), (timer) {
-        double latStep = 0.00025;
-        double lngStep = 0.00025;
+      _simulationTimer = Timer.periodic(const Duration(milliseconds: 100), (timer) {
+        double latStep = 0.000025;
+        double lngStep = 0.000025;
+
         if (_plannedEnd != null) {
           double dist = Geolocator.distanceBetween(_currentPosition.latitude, _currentPosition.longitude, _plannedEnd!.latitude, _plannedEnd!.longitude);
-          if (dist < 12) { 
-            _updatePosition(_plannedEnd!, 0.0); 
-            _toggleSimulation(); 
-            return; 
+          if (dist < 2) {
+            _updatePosition(_plannedEnd!, 0.0);
+            _toggleSimulation();
+            return;
           }
-          latStep = (_plannedEnd!.latitude - _currentPosition.latitude) / (max(dist / 8, 1));
-          lngStep = (_plannedEnd!.longitude - _currentPosition.longitude) / (max(dist / 8, 1));
+          latStep = (_plannedEnd!.latitude - _currentPosition.latitude) / (max(dist / 0.8, 1));
+          lngStep = (_plannedEnd!.longitude - _currentPosition.longitude) / (max(dist / 0.8, 1));
         }
+
         LatLng nextPoint = LatLng(_currentPosition.latitude + latStep, _currentPosition.longitude + lngStep);
-        _updatePosition(nextPoint, 3.5 + Random().nextDouble());
+        _updatePosition(nextPoint, 3.5 + Random().nextDouble() * 0.5);
       });
     }
   }