Improved code quality (refactoring & stricter linting) (#1594)

* add lints, code style improvements, add assert messages

* use documentation comments for methods

https://dart.dev/language/comments#documentation-comments

* better callback parameter names, dart format

* fix lazy fields in `MapCamera`

* use documentation comments part 2

* use `@immutable` for immutables, const constructors where possible

* refactor loops

* use math min() / max()

* remove omit_local_variable_types lint

* use full method bodies instead of `=>`

* typo

* Fixed conflict resolution bugs

* Fix lint warning

* remove cupertino imports

fix
https://github.com/fleaflet/flutter_map/pull/1594/files/a50be82dfbfc92fff753c7b704d4b98bb63a6d81#r1275362713
https://github.com/fleaflet/flutter_map/pull/1594/files/a50be82dfbfc92fff753c7b704d4b98bb63a6d81#r1275360404

* remove non null cast

* revert list mapping

https://github.com/fleaflet/flutter_map/pull/1594/files/38d7250da5524779449cab91559d1b25234641da..df4b2053e79c71704b02fd72dcfe52bfd28d6888#r1270268326

analysis_options.yaml

@@ -27,3 +27,19 @@ linter:
     type_annotate_public_apis: true
     unnecessary_statements: true
     use_named_constants: true
+    use_super_parameters: true
+    cast_nullable_to_non_nullable: true
+    only_throw_errors: true
+    sort_unnamed_constructors_first: true
+    prefer_asserts_with_message: true
+    missing_whitespace_between_adjacent_strings: true
+    avoid_multiple_declarations_per_line: true
+    noop_primitive_operations: true
+    avoid_void_async: true
+    avoid_redundant_argument_values: true
+    avoid_types_on_closure_parameters: true
+    unnecessary_null_checks: true
+    prefer_single_quotes: true
+    unnecessary_parenthesis: true
+    use_if_null_to_convert_nulls_to_bools: true
+    matching_super_parameters: true

example/lib/pages/custom_crs/custom_crs.dart

@@ -80,7 +80,7 @@ class _CustomCrsPageState extends State<CustomCrsPage> {
       // Some goeserver changes origin based on zoom level
       // and some are not at all (use explicit/implicit null or use [Point(0, 0)])
       // @see https://github.com/kartena/Proj4Leaflet/pull/171
-      origins: [const Point(0, 0)],
+      origins: const [Point(0, 0)],
       // Scale factors (pixels per projection unit, for example pixels/meter) for zoom levels;
       // specify either scales or resolutions, not both
       scales: null,
@@ -167,7 +167,7 @@ class _CustomCrsPageState extends State<CustomCrsPage> {
                         format: 'image/jpeg',
                         baseUrl:
                             'https://www.gebco.net/data_and_products/gebco_web_services/north_polar_view_wms/mapserv?',
-                        layers: ['gebco_north_polar_view'],
+                        layers: const ['gebco_north_polar_view'],
                       ),
                     ),
                   ),

example/lib/pages/epsg3413_crs.dart

@@ -57,7 +57,7 @@ class _EPSG3413PageState extends State<EPSG3413Page> {
       proj4Projection: epsg3413,
       resolutions: resolutions,
       bounds: epsg3413Bounds,
-      origins: [const Point(0, 0)],
+      origins: const [Point(0, 0)],
       scales: null,
       transformation: null,
     );
@@ -67,8 +67,8 @@ class _EPSG3413PageState extends State<EPSG3413Page> {
   Widget build(BuildContext context) {
     // These circles should have the same pixel radius on the map
     final circles = [
-      CircleMarker(
-        point: const LatLng(90, 0),
+      const CircleMarker(
+        point: LatLng(90, 0),
         radius: 20000,
         useRadiusInMeter: true,
         color: Colors.yellow,
@@ -162,7 +162,7 @@ class _EPSG3413PageState extends State<EPSG3413Page> {
                         format: 'image/jpeg',
                         baseUrl:
                             'https://www.gebco.net/data_and_products/gebco_web_services/north_polar_view_wms/mapserv?',
-                        layers: ['gebco_north_polar_view'],
+                        layers: const ['gebco_north_polar_view'],
                       ),
                     ),
                   ),

example/lib/pages/epsg4326_crs.dart

@@ -34,7 +34,7 @@ class EPSG4326Page extends StatelessWidget {
                     wmsOptions: WMSTileLayerOptions(
                       crs: const Epsg4326(),
                       baseUrl: 'https://ows.mundialis.de/services/service?',
-                      layers: ['TOPO-OSM-WMS'],
+                      layers: const ['TOPO-OSM-WMS'],
                     ),
                     userAgentPackageName: 'dev.fleaflet.flutter_map.example',
                   ),

example/lib/pages/wms_tile_layer.dart

@@ -54,7 +54,7 @@ class WMSLayerPage extends StatelessWidget {
                   TileLayer(
                     wmsOptions: WMSTileLayerOptions(
                       baseUrl: 'https://{s}.s2maps-tiles.eu/wms/?',
-                      layers: ['s2cloudless-2021_3857'],
+                      layers: const ['s2cloudless-2021_3857'],
                     ),
                     subdomains: const ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'],
                     userAgentPackageName: 'dev.fleaflet.flutter_map.example',

lib/src/geo/crs.dart

@@ -11,6 +11,7 @@ import 'package:proj4dart/proj4dart.dart' as proj4;
 ///
 /// The main objective of a CRS is to handle the conversion between surface
 /// points of objects of different dimensions. In our case 3D and 2D objects.
+@immutable
 abstract class Crs {
   const Crs();
 
@@ -26,15 +27,15 @@ abstract class Crs {
     try {
       final projectedPoint = projection.project(latlng);
       final scale = this.scale(zoom);
-      return transformation.transform(projectedPoint, scale.toDouble());
-    } catch (e) {
+      return transformation.transform(projectedPoint, scale);
+    } catch (_) {
       return const Point(0, 0);
     }
   }
 
   /// Converts a map point to the sphere coordinate (at a certain zoom).
-  LatLng pointToLatLng(Point point, double zoom) => projection
-      .unproject(transformation.untransform(point, scale(zoom).toDouble()));
+  LatLng pointToLatLng(Point point, double zoom) =>
+      projection.unproject(transformation.untransform(point, scale(zoom)));
 
   /// Zoom to Scale function.
   double scale(double zoom) => 256.0 * math.pow(2, zoom);
@@ -48,8 +49,8 @@ abstract class Crs {
 
     final b = projection.bounds!;
     final s = scale(zoom);
-    final min = transformation.transform(b.min, s.toDouble());
-    final max = transformation.transform(b.max, s.toDouble());
+    final min = transformation.transform(b.min, s);
+    final max = transformation.transform(b.max, s);
     return Bounds(min, max);
   }
 
@@ -61,6 +62,7 @@ abstract class Crs {
 }
 
 // Custom CRS for non geographical maps
+@immutable
 class CrsSimple extends Crs {
   @override
   final String code = 'CRS.SIMPLE';
@@ -71,7 +73,7 @@ class CrsSimple extends Crs {
   @override
   final Transformation transformation;
 
-  CrsSimple()
+  const CrsSimple()
       : projection = const _LonLat(),
         transformation = const Transformation(1, 0, -1, 0),
         super();
@@ -86,6 +88,7 @@ class CrsSimple extends Crs {
   (double, double)? get wrapLng => null;
 }
 
+@immutable
 abstract class Earth extends Crs {
   @override
   bool get infinite => false;
@@ -100,6 +103,7 @@ abstract class Earth extends Crs {
 }
 
 /// The most common CRS used for rendering maps.
+@immutable
 class Epsg3857 extends Earth {
   @override
   final String code = 'EPSG:3857';
@@ -123,6 +127,7 @@ class Epsg3857 extends Earth {
 }
 
 /// A common CRS among GIS enthusiasts. Uses simple Equirectangular projection.
+@immutable
 class Epsg4326 extends Earth {
   @override
   final String code = 'EPSG:4326';
@@ -140,6 +145,7 @@ class Epsg4326 extends Earth {
 }
 
 /// Custom CRS
+@immutable
 class Proj4Crs extends Crs {
   @override
   final String code;
@@ -163,7 +169,7 @@ class Proj4Crs extends Crs {
 
   final List<double> _scales;
 
-  Proj4Crs._({
+  const Proj4Crs._({
     required this.code,
     required this.projection,
     required this.transformation,
@@ -229,17 +235,16 @@ class Proj4Crs extends Crs {
       final scale = this.scale(zoom);
       final transformation = _getTransformationByZoom(zoom);
 
-      return transformation.transform(projectedPoint, scale.toDouble());
-    } catch (e) {
+      return transformation.transform(projectedPoint, scale);
+    } catch (_) {
       return const Point(0, 0);
     }
   }
 
   /// Converts a map point to the sphere coordinate (at a certain zoom).
   @override
-  LatLng pointToLatLng(Point point, double zoom) =>
-      projection.unproject(_getTransformationByZoom(zoom)
-          .untransform(point, scale(zoom).toDouble()));
+  LatLng pointToLatLng(Point point, double zoom) => projection.unproject(
+      _getTransformationByZoom(zoom).untransform(point, scale(zoom)));
 
   /// Rescales the bounds to a given zoom value.
   @override
@@ -251,8 +256,8 @@ class Proj4Crs extends Crs {
 
     final transformation = _getTransformationByZoom(zoom);
 
-    final min = transformation.transform(b.min, s.toDouble());
-    final max = transformation.transform(b.max, s.toDouble());
+    final min = transformation.transform(b.min, s);
+    final max = transformation.transform(b.max, s);
     return Bounds(min, max);
   }
 
@@ -267,7 +272,7 @@ class Proj4Crs extends Crs {
       final baseScale = _scales[iZoom];
       final nextScale = _scales[iZoom + 1];
       final scaleDiff = nextScale - baseScale;
-      final zDiff = (zoom - iZoom);
+      final zDiff = zoom - iZoom;
       return baseScale + scaleDiff * zDiff;
     }
   }
@@ -319,6 +324,7 @@ class Proj4Crs extends Crs {
   }
 }
 
+@immutable
 abstract class Projection {
   const Projection();
 
@@ -367,6 +373,7 @@ class _LonLat extends Projection {
   }
 }
 
+@immutable
 class SphericalMercator extends Projection {
   static const int r = 6378137;
   static const double maxLatitude = 85.0511287798;
@@ -402,6 +409,7 @@ class SphericalMercator extends Projection {
   }
 }
 
+@immutable
 class _Proj4Projection extends Projection {
   final proj4.Projection epsg4326;
 
@@ -432,6 +440,7 @@ class _Proj4Projection extends Projection {
   }
 }
 
+@immutable
 class Transformation {
   final num a;
   final num b;

lib/src/geo/latlng_bounds.dart

@@ -13,31 +13,21 @@ class LatLngBounds {
     LatLng corner2,
   ) : this.fromPoints([corner1, corner2]);
 
-  LatLngBounds.fromPoints(List<LatLng> points) : assert(points.isNotEmpty) {
+  LatLngBounds.fromPoints(List<LatLng> points)
+      : assert(
+          points.isNotEmpty,
+          'LatLngBounds cannot be created with an empty List of LatLng',
+        ) {
     double minX = 180;
     double maxX = -180;
     double minY = 90;
     double maxY = -90;
 
     for (final point in points) {
-      final double x = point.longitude;
-      final double y = point.latitude;
-
-      if (minX > x) {
-        minX = x;
-      }
-
-      if (minY > y) {
-        minY = y;
-      }
-
-      if (maxX < x) {
-        maxX = x;
-      }
-
-      if (maxY < y) {
-        maxY = y;
-      }
+      minX = math.min<double>(minX, point.longitude);
+      minY = math.min<double>(minY, point.latitude);
+      maxX = math.max<double>(maxX, point.longitude);
+      maxY = math.max<double>(maxY, point.latitude);
     }
 
     _sw = LatLng(minY, minX);