Migrate LatLngBounds to nullsafety

.gitignore

@@ -75,3 +75,6 @@ pubspec.lock
 !**/ios/**/default.mode2v3
 !**/ios/**/default.pbxuser
 !**/ios/**/default.perspectivev3
+
+# Coverage files
+coverage/

example/lib/pages/animated_map_controller.dart

@@ -26,9 +26,9 @@ class AnimatedMapControllerPageState extends State<AnimatedMapControllerPage>
   // See https://github.com/flutter/flutter/issues/14317#issuecomment-361085869
   // This project didn't require that change, so YMMV.
 
-  static LatLng london = LatLng(51.5, -0.09);
-  static LatLng paris = LatLng(48.8566, 2.3522);
-  static LatLng dublin = LatLng(53.3498, -6.2603);
+  static final london = LatLng(51.5, -0.09);
+  static final paris = LatLng(48.8566, 2.3522);
+  static final dublin = LatLng(53.3498, -6.2603);
 
   late final MapController mapController;
 
@@ -142,10 +142,12 @@ class AnimatedMapControllerPageState extends State<AnimatedMapControllerPage>
                 children: <Widget>[
                   MaterialButton(
                     onPressed: () {
-                      final bounds = LatLngBounds();
-                      bounds.extend(dublin);
-                      bounds.extend(paris);
-                      bounds.extend(london);
+                      final bounds = LatLngBounds.fromPoints([
+                        dublin,
+                        paris,
+                        london,
+                      ]);
+
                       mapController.fitBounds(
                         bounds,
                         options: const FitBoundsOptions(
@@ -157,10 +159,11 @@ class AnimatedMapControllerPageState extends State<AnimatedMapControllerPage>
                   ),
                   MaterialButton(
                     onPressed: () {
-                      final bounds = LatLngBounds();
-                      bounds.extend(dublin);
-                      bounds.extend(paris);
-                      bounds.extend(london);
+                      final bounds = LatLngBounds.fromPoints([
+                        dublin,
+                        paris,
+                        london,
+                      ]);
 
                       final centerZoom =
                           mapController.centerZoomFitBounds(bounds);

example/lib/pages/map_controller.dart

@@ -102,10 +102,12 @@ class MapControllerPageState extends State<MapControllerPage> {
                 children: <Widget>[
                   MaterialButton(
                     onPressed: () {
-                      final bounds = LatLngBounds();
-                      bounds.extend(dublin);
-                      bounds.extend(paris);
-                      bounds.extend(london);
+                      final bounds = LatLngBounds.fromPoints([
+                        dublin,
+                        paris,
+                        london,
+                      ]);
+
                       _mapController.fitBounds(
                         bounds,
                         options: const FitBoundsOptions(

lib/src/geo/latlng_bounds.dart

@@ -5,19 +5,15 @@ import 'package:latlong2/latlong.dart';
 /// Data structure representing rectangular bounding box constrained by its
 /// northwest and southeast corners
 class LatLngBounds {
-  LatLng? _sw;
-  LatLng? _ne;
+  late final LatLng _sw;
+  late final LatLng _ne;
 
-  LatLngBounds([LatLng? corner1, LatLng? corner2]) {
-    extend(corner1);
-    extend(corner2);
-  }
-
-  LatLngBounds.fromPoints(List<LatLng> points) {
-    if (points.isEmpty) {
-      return;
-    }
+  LatLngBounds(
+    LatLng corner1,
+    LatLng corner2,
+  ) : this.fromPoints([corner1, corner2]);
 
+  LatLngBounds.fromPoints(List<LatLng> points) : assert(points.isNotEmpty) {
     double minX = 180;
     double maxX = -180;
     double minY = 90;
@@ -50,10 +46,7 @@ class LatLngBounds {
 
   /// Expands bounding box by [latlng] coordinate point. This method mutates
   /// the bounds object on which it is called.
-  void extend(LatLng? latlng) {
-    if (latlng == null) {
-      return;
-    }
+  void extend(LatLng latlng) {
     _extend(latlng, latlng);
   }
 
@@ -64,35 +57,30 @@ class LatLngBounds {
     _extend(bounds._sw, bounds._ne);
   }
 
-  void _extend(LatLng? sw2, LatLng? ne2) {
-    if (_sw == null && _ne == null) {
-      _sw = LatLng(sw2!.latitude, sw2.longitude);
-      _ne = LatLng(ne2!.latitude, ne2.longitude);
-    } else {
-      _sw!.latitude = math.min(sw2!.latitude, _sw!.latitude);
-      _sw!.longitude = math.min(sw2.longitude, _sw!.longitude);
-      _ne!.latitude = math.max(ne2!.latitude, _ne!.latitude);
-      _ne!.longitude = math.max(ne2.longitude, _ne!.longitude);
-    }
+  void _extend(LatLng sw2, LatLng ne2) {
+    _sw.latitude = math.min(sw2.latitude, _sw.latitude);
+    _sw.longitude = math.min(sw2.longitude, _sw.longitude);
+    _ne.latitude = math.max(ne2.latitude, _ne.latitude);
+    _ne.longitude = math.max(ne2.longitude, _ne.longitude);
   }
 
   /// Obtain west edge of the bounds
-  double get west => southWest!.longitude;
+  double get west => southWest.longitude;
 
   /// Obtain south edge of the bounds
-  double get south => southWest!.latitude;
+  double get south => southWest.latitude;
 
   /// Obtain east edge of the bounds
-  double get east => northEast!.longitude;
+  double get east => northEast.longitude;
 
   /// Obtain north edge of the bounds
-  double get north => northEast!.latitude;
+  double get north => northEast.latitude;
 
   /// Obtain coordinates of southwest corner of the bounds
-  LatLng? get southWest => _sw;
+  LatLng get southWest => _sw;
 
   /// Obtain coordinates of northeast corner of the bounds
-  LatLng? get northEast => _ne;
+  LatLng get northEast => _ne;
 
   /// Obtain coordinates of northwest corner of the bounds
   LatLng get northWest => LatLng(north, west);
@@ -112,12 +100,12 @@ class LatLngBounds {
        lambda: lng
     */
 
-    final phi1 = southWest!.latitudeInRad;
-    final lambda1 = southWest!.longitudeInRad;
-    final phi2 = northEast!.latitudeInRad;
+    final phi1 = southWest.latitudeInRad;
+    final lambda1 = southWest.longitudeInRad;
+    final phi2 = northEast.latitudeInRad;
 
-    final dLambda = degToRadian(northEast!.longitude -
-        southWest!.longitude); // delta lambda = lambda2-lambda1
+    final dLambda = degToRadian(northEast.longitude -
+        southWest.longitude); // delta lambda = lambda2-lambda1
 
     final bx = math.cos(phi2) * math.cos(dLambda);
     final by = math.cos(phi2) * math.sin(dLambda);
@@ -130,59 +118,56 @@ class LatLngBounds {
   }
 
   /// Checks whether bound object is valid
-  bool get isValid {
-    return _sw != null && _ne != null;
-  }
+  /// TODO: remove this property in the next major release.
+  @Deprecated('This method is unnecessary and will be removed in the future.')
+  bool get isValid => true;
 
   /// Checks whether [point] is inside bounds
-  bool contains(LatLng? point) {
-    if (!isValid) {
-      return false;
-    }
+  bool contains(LatLng point) {
     final sw2 = point;
     final ne2 = point;
     return containsBounds(LatLngBounds(sw2, ne2));
   }
 
   /// Checks whether [bounds] is contained inside bounds
   bool containsBounds(LatLngBounds bounds) {
-    final sw2 = bounds._sw!;
+    final sw2 = bounds._sw;
     final ne2 = bounds._ne;
-    return (sw2.latitude >= _sw!.latitude) &&
-        (ne2!.latitude <= _ne!.latitude) &&
-        (sw2.longitude >= _sw!.longitude) &&
-        (ne2.longitude <= _ne!.longitude);
+    return (sw2.latitude >= _sw.latitude) &&
+        (ne2.latitude <= _ne.latitude) &&
+        (sw2.longitude >= _sw.longitude) &&
+        (ne2.longitude <= _ne.longitude);
   }
 
   /// Checks whether at least one edge of [bounds] is overlapping with some
   /// other edge of bounds
-  bool isOverlapping(LatLngBounds? bounds) {
-    if (!isValid) {
-      return false;
-    }
+  bool isOverlapping(LatLngBounds bounds) {
     /* check if bounding box rectangle is outside the other, if it is then it's
        considered not overlapping
     */
-    if (_sw!.latitude > bounds!._ne!.latitude ||
-        _ne!.latitude < bounds._sw!.latitude ||
-        _ne!.longitude < bounds._sw!.longitude ||
-        _sw!.longitude > bounds._ne!.longitude) {
+    if (_sw.latitude > bounds._ne.latitude ||
+        _ne.latitude < bounds._sw.latitude ||
+        _ne.longitude < bounds._sw.longitude ||
+        _sw.longitude > bounds._ne.longitude) {
       return false;
     }
     return true;
   }
 
   /// Expands bounds by decimal degrees unlike [extend] or [extendBounds]
   void pad(double bufferRatio) {
-    final heightBuffer = (_sw!.latitude - _ne!.latitude).abs() * bufferRatio;
-    final widthBuffer = (_sw!.longitude - _ne!.longitude).abs() * bufferRatio;
+    final heightBuffer = (_sw.latitude - _ne.latitude).abs() * bufferRatio;
+    final widthBuffer = (_sw.longitude - _ne.longitude).abs() * bufferRatio;
+
+    _sw.latitude = _sw.latitude - heightBuffer;
+    _sw.longitude = _sw.longitude - widthBuffer;
 
-    _sw = LatLng(_sw!.latitude - heightBuffer, _sw!.longitude - widthBuffer);
-    _ne = LatLng(_ne!.latitude + heightBuffer, _ne!.longitude + widthBuffer);
+    _ne.latitude = _ne.latitude + heightBuffer;
+    _ne.longitude = _ne.longitude + widthBuffer;
   }
 
   @override
-  int get hashCode => _sw.hashCode + _ne.hashCode;
+  int get hashCode => Object.hash(_sw, _ne);
 
   @override
   bool operator ==(Object other) =>

lib/src/layer/tile_layer/tile_layer.dart

@@ -700,8 +700,8 @@ class _TileLayerState extends State<TileLayer> with TickerProviderStateMixin {
 
   Bounds _latLngBoundsToPixelBounds(
       FlutterMapState map, LatLngBounds bounds, double thisZoom) {
-    final swPixel = map.project(bounds.southWest!, thisZoom).floor();
-    final nePixel = map.project(bounds.northEast!, thisZoom).ceil();
+    final swPixel = map.project(bounds.southWest, thisZoom).floor();
+    final nePixel = map.project(bounds.northEast, thisZoom).ceil();
     final pxBounds = Bounds(swPixel, nePixel);
     return pxBounds;
   }

lib/src/map/flutter_map_state.dart

@@ -421,7 +421,7 @@ class FlutterMapState extends MapGestureMixin
     newZoom = fitZoomToBounds(newZoom);
     final mapMoved = newCenter != _center || newZoom != _zoom;
 
-    if (!mapMoved || !_calculateBounds().isValid) {
+    if (!mapMoved) {
       return false;
     }
 
@@ -483,18 +483,12 @@ class FlutterMapState extends MapGestureMixin
   }
 
   void fitBounds(LatLngBounds bounds, FitBoundsOptions options) {
-    if (!bounds.isValid) {
-      throw Exception('Bounds are not valid.');
-    }
     final target = getBoundsCenterZoom(bounds, options);
     move(target.center, target.zoom, source: MapEventSource.fitBounds);
   }
 
   CenterZoom centerZoomFitBounds(
       LatLngBounds bounds, FitBoundsOptions options) {
-    if (!bounds.isValid) {
-      throw Exception('Bounds are not valid.');
-    }
     return getBoundsCenterZoom(bounds, options);
   }
 
@@ -523,8 +517,8 @@ class FlutterMapState extends MapGestureMixin
     zoom = math.min(options.maxZoom, zoom);
 
     final paddingOffset = (paddingBR - paddingTL) / 2;
-    final swPoint = project(bounds.southWest!, zoom);
-    final nePoint = project(bounds.northEast!, zoom);
+    final swPoint = project(bounds.southWest, zoom);
+    final nePoint = project(bounds.northEast, zoom);
     final center = unproject((swPoint + nePoint) / 2 + paddingOffset, zoom);
     return CenterZoom(
       center: center,
@@ -608,8 +602,8 @@ class FlutterMapState extends MapGestureMixin
       LatLng testCenter, double testZoom, LatLngBounds maxBounds) {
     LatLng? newCenter;
 
-    final swPixel = project(maxBounds.southWest!, testZoom);
-    final nePixel = project(maxBounds.northEast!, testZoom);
+    final swPixel = project(maxBounds.southWest, testZoom);
+    final nePixel = project(maxBounds.northEast, testZoom);
 
     final centerPix = project(testCenter, testZoom);
 
@@ -729,14 +723,12 @@ class FlutterMapState extends MapGestureMixin
   double? _safeAreaZoom;
 
   //if there is a pan boundary, do not cross
-  bool isOutOfBounds(LatLng? center) {
+  bool isOutOfBounds(LatLng center) {
     if (options.adaptiveBoundaries) {
       return !_safeArea!.contains(center);
     }
     if (options.swPanBoundary != null && options.nePanBoundary != null) {
-      if (center == null) {
-        return true;
-      } else if (center.latitude < options.swPanBoundary!.latitude ||
+      if (center.latitude < options.swPanBoundary!.latitude ||
           center.latitude > options.nePanBoundary!.latitude) {
         return true;
       } else if (center.longitude < options.swPanBoundary!.longitude ||
@@ -817,7 +809,7 @@ class _SafeArea {
         isLatitudeBlocked = southWest.latitude > northEast.latitude,
         isLongitudeBlocked = southWest.longitude > northEast.longitude;
 
-  bool contains(LatLng? point) =>
+  bool contains(LatLng point) =>
       isLatitudeBlocked || isLongitudeBlocked ? false : bounds.contains(point);
 
   LatLng containPoint(LatLng point, LatLng fallback) => LatLng(

test/geo/latlng_bounds_test.dart

@@ -0,0 +1,51 @@
+import 'package:flutter_map/src/geo/latlng_bounds.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:latlong2/latlong.dart';
+
+void main() {
+  group('LatLngBounds', () {
+    final london = LatLng(51.5, -0.09);
+    final paris = LatLng(48.8566, 2.3522);
+    final dublin = LatLng(53.3498, -6.2603);
+
+    group('LatLngBounds constructor', () {
+      test('with dublin, paris', () {
+        final bounds = LatLngBounds(dublin, paris);
+
+        expect(bounds, LatLngBounds.fromPoints([dublin, paris]));
+      });
+    });
+
+    group('LatLngBounds.fromPoints', () {
+      test('throw AssertionError if points is empty', () {
+        expect(() => LatLngBounds.fromPoints([]), throwsAssertionError);
+      });
+
+      test('with dublin, paris, london', () {
+        final bounds = LatLngBounds.fromPoints([
+          dublin,
+          paris,
+          london,
+        ]);
+
+        final sw = bounds.southWest;
+        final ne = bounds.northEast;
+
+        expect(sw.latitude, 48.8566);
+        expect(sw.longitude, -6.2603);
+        expect(ne.latitude, 53.3498);
+        expect(ne.longitude, 2.3522);
+      });
+    });
+
+    group('hashCode', () {
+      test('with dublin, paris', () {
+        final bounds1 = LatLngBounds(dublin, paris);
+        final bounds2 = LatLngBounds(dublin, paris);
+
+        expect(bounds1 == bounds2, isTrue);
+        expect(bounds1.hashCode, bounds2.hashCode);
+      });
+    });
+  });
+}