cleanup code

analysis_options.yaml

@@ -1,4 +1,208 @@
+# This file configures the analyzer, which statically analyzes Dart code to
+# check for errors, warnings, and lints.
+#
+# The issues identified by the analyzer are surfaced in the UI of Dart-enabled
+# IDEs (https://dart.dev/tools#ides-and-editors). The analyzer can also be
+# invoked from the command line by running `flutter analyze`.
+
+# The following line activates a set of recommended lints for Flutter apps,
+# packages, and plugins designed to encourage good coding practices.
 include: package:flutter_lints/flutter.yaml
 
+linter:
+  # The lint rules applied to this project can be customized in the
+  # section below to disable rules from the `package:flutter_lints/flutter.yaml`
+  # included above or to enable additional rules. A list of all available lints
+  # and their documentation is published at
+  # https://dart-lang.github.io/linter/lints/index.html.
+  #
+  # Instead of disabling a lint rule for the entire project in the
+  # section below, it can also be suppressed for a single line of code
+  # or a specific dart file by using the `// ignore: name_of_lint` and
+  # `// ignore_for_file: name_of_lint` syntax on the line or in the file
+  # producing the lint.
+  rules:
+    always_use_package_imports: true
+    avoid_dynamic_calls: true
+    avoid_empty_else: true
+    avoid_print: true
+    avoid_relative_lib_imports: true
+    avoid_returning_null_for_future: true
+    avoid_slow_async_io: true
+    avoid_type_to_string: true
+    avoid_types_as_parameter_names: true
+    avoid_web_libraries_in_flutter: true
+    cancel_subscriptions: true
+    close_sinks: true
+    comment_references: false
+    control_flow_in_finally: true
+    diagnostic_describe_all_properties: false
+    empty_statements: true
+    hash_and_equals: true
+    invariant_booleans: true
+    iterable_contains_unrelated_type: true
+    list_remove_unrelated_type: true
+    literal_only_boolean_expressions: true
+    no_adjacent_strings_in_list: true
+    no_duplicate_case_values: true
+    no_logic_in_create_state: true
+    prefer_void_to_null: true
+    test_types_in_equals: true
+    throw_in_finally: true
+    unnecessary_statements: true
+    unrelated_type_equality_checks: true
+    use_build_context_synchronously: true
+    use_key_in_widget_constructors: true
+    valid_regexps: true
+    always_declare_return_types: true
+    always_put_control_body_on_new_line: true
+    always_put_required_named_parameters_first: true
+    always_require_non_null_named_parameters: true
+    always_specify_types: false
+    annotate_overrides: true
+    avoid_annotating_with_dynamic: false
+    avoid_bool_literals_in_conditional_expressions: true
+    avoid_catches_without_on_clauses: false
+    avoid_catching_errors: false
+    avoid_classes_with_only_static_members: true
+    avoid_double_and_int_checks: true
+    avoid_equals_and_hash_code_on_mutable_classes: false
+    avoid_escaping_inner_quotes: false
+    avoid_field_initializers_in_const_classes: true
+    avoid_function_literals_in_foreach_calls: true
+    avoid_implementing_value_types: true
+    avoid_init_to_null: true
+    avoid_multiple_declarations_per_line: true
+    avoid_null_checks_in_equality_operators: true
+    avoid_private_typedef_functions: true
+    avoid_renaming_method_parameters: true
+    avoid_return_types_on_setters: true
+    avoid_returning_null: true
+    avoid_returning_null_for_void: true
+    avoid_returning_this: true
+    avoid_shadowing_type_parameters: true
+    avoid_single_cascade_in_expression_statements: true
+    avoid_types_on_closure_parameters: false
+    avoid_unnecessary_containers: false
+    avoid_unused_constructor_parameters: true
+    avoid_void_async: true
+    await_only_futures: true
+    camel_case_extensions: true
+    camel_case_types: true
+    cascade_invocations: true
+    cast_nullable_to_non_nullable: true
+    constant_identifier_names: true
+    curly_braces_in_flow_control_structures: true
+    deprecated_consistency: true
+    directives_ordering: true
+    do_not_use_environment: true
+    empty_catches: true
+    empty_constructor_bodies: true
+    eol_at_end_of_file: true
+    exhaustive_cases: true
+    file_names: true
+    flutter_style_todos: true
+    implementation_imports: true
+    join_return_with_assignment: true
+    leading_newlines_in_multiline_strings: true
+    library_names: true
+    library_prefixes: true
+    library_private_types_in_public_api: true
+    lines_longer_than_80_chars: true
+    missing_whitespace_between_adjacent_strings: true
+    no_default_cases: true
+    non_constant_identifier_names: true
+    noop_primitive_operations: true
+    null_check_on_nullable_type_parameter: true
+    null_closures: true
+    omit_local_variable_types: true
+    one_member_abstracts: true
+    only_throw_errors: true
+    overridden_fields: true
+    package_api_docs: true
+    package_prefixed_library_names: true
+    parameter_assignments: true
+    prefer_adjacent_string_concatenation: true
+    prefer_asserts_in_initializer_lists: true
+    prefer_asserts_with_message: true
+    prefer_collection_literals: true
+    prefer_conditional_assignment: true
+    prefer_const_constructors: false
+    prefer_const_constructors_in_immutables: true
+    prefer_const_declarations: false
+    prefer_const_literals_to_create_immutables: false
+    prefer_constructors_over_static_methods: true
+    prefer_contains: true
+    prefer_double_quotes: false
+    prefer_equal_for_default_values: true
+    prefer_expression_function_bodies: false
+    prefer_final_fields: true
+    prefer_final_in_for_each: true
+    prefer_final_locals: false
+    prefer_final_parameters: false
+    prefer_for_elements_to_map_fromIterable: true
+    prefer_foreach: true
+    prefer_function_declarations_over_variables: true
+    prefer_generic_function_type_aliases: true
+    prefer_if_elements_to_conditional_expressions: true
+    prefer_if_null_operators: true
+    prefer_initializing_formals: true
+    prefer_inlined_adds: true
+    prefer_int_literals: false
+    prefer_interpolation_to_compose_strings: true
+    prefer_is_empty: true
+    prefer_is_not_empty: true
+    prefer_is_not_operator: true
+    prefer_iterable_whereType: true
+    prefer_mixin: true
+    prefer_null_aware_method_calls: true
+    prefer_null_aware_operators: true
+    prefer_single_quotes: true
+    prefer_spread_collections: true
+    prefer_typing_uninitialized_variables: true
+    public_member_api_docs: false
+    recursive_getters: true
+    require_trailing_commas: true
+    sized_box_for_whitespace: true
+    slash_for_doc_comments: true
+    sort_child_properties_last: true
+    sort_constructors_first: true
+    sort_unnamed_constructors_first: true
+    tighten_type_of_initializing_formals: true
+    type_annotate_public_apis: true
+    type_init_formals: true
+    unawaited_futures: true
+    unnecessary_await_in_return: true
+    unnecessary_brace_in_string_interps: true
+    unnecessary_const: false
+    unnecessary_constructor_name: true
+    unnecessary_final: true
+    unnecessary_getters_setters: true
+    unnecessary_lambdas: true
+    unnecessary_new: true
+    unnecessary_null_aware_assignments: true
+    unnecessary_null_checks: true
+    unnecessary_null_in_if_null_operators: true
+    unnecessary_nullable_for_final_variable_declarations: true
+    unnecessary_overrides: true
+    unnecessary_parenthesis: true
+    unnecessary_raw_strings: true
+    unnecessary_string_escapes: true
+    unnecessary_string_interpolations: true
+    unnecessary_this: true
+    use_full_hex_values_for_flutter_colors: true
+    use_function_type_syntax_for_parameters: true
+    use_if_null_to_convert_nulls_to_bools: true
+    use_is_even_rather_than_modulo: true
+    use_late_for_private_fields_and_variables: true
+    use_named_constants: true
+    use_raw_strings: false
+    use_rethrow_when_possible: true
+    use_setters_to_change_properties: true
+    use_string_buffers: true
+    use_test_throws_matchers: true
+    use_to_and_as_if_applicable: true
+    void_checks: true
+
 # Additional information about this file can be found at
 # https://dart.dev/guides/language/analysis-options

example/analysis_options.yaml

@@ -22,8 +22,188 @@ linter:
   # `// ignore_for_file: name_of_lint` syntax on the line or in the file
   # producing the lint.
   rules:
-    # avoid_print: false  # Uncomment to disable the `avoid_print` rule
+    always_use_package_imports: true
-    # prefer_single_quotes: true  # Uncomment to enable the `prefer_single_quotes` rule
+    avoid_dynamic_calls: true
+    avoid_empty_else: true
+    avoid_print: true
+    avoid_relative_lib_imports: true
+    avoid_returning_null_for_future: true
+    avoid_slow_async_io: true
+    avoid_type_to_string: true
+    avoid_types_as_parameter_names: true
+    avoid_web_libraries_in_flutter: true
+    cancel_subscriptions: true
+    close_sinks: true
+    comment_references: false
+    control_flow_in_finally: true
+    diagnostic_describe_all_properties: false
+    empty_statements: true
+    hash_and_equals: true
+    invariant_booleans: true
+    iterable_contains_unrelated_type: true
+    list_remove_unrelated_type: true
+    literal_only_boolean_expressions: true
+    no_adjacent_strings_in_list: true
+    no_duplicate_case_values: true
+    no_logic_in_create_state: true
+    prefer_void_to_null: true
+    test_types_in_equals: true
+    throw_in_finally: true
+    unnecessary_statements: true
+    unrelated_type_equality_checks: true
+    use_build_context_synchronously: true
+    use_key_in_widget_constructors: true
+    valid_regexps: true
+    always_declare_return_types: true
+    always_put_control_body_on_new_line: true
+    always_put_required_named_parameters_first: true
+    always_require_non_null_named_parameters: true
+    always_specify_types: false
+    annotate_overrides: true
+    avoid_annotating_with_dynamic: false
+    avoid_bool_literals_in_conditional_expressions: true
+    avoid_catches_without_on_clauses: false
+    avoid_catching_errors: false
+    avoid_classes_with_only_static_members: true
+    avoid_double_and_int_checks: true
+    avoid_equals_and_hash_code_on_mutable_classes: false
+    avoid_escaping_inner_quotes: false
+    avoid_field_initializers_in_const_classes: true
+    avoid_function_literals_in_foreach_calls: true
+    avoid_implementing_value_types: true
+    avoid_init_to_null: true
+    avoid_multiple_declarations_per_line: true
+    avoid_null_checks_in_equality_operators: true
+    avoid_private_typedef_functions: true
+    avoid_renaming_method_parameters: true
+    avoid_return_types_on_setters: true
+    avoid_returning_null: true
+    avoid_returning_null_for_void: true
+    avoid_returning_this: true
+    avoid_shadowing_type_parameters: true
+    avoid_single_cascade_in_expression_statements: true
+    avoid_types_on_closure_parameters: false
+    avoid_unnecessary_containers: false
+    avoid_unused_constructor_parameters: true
+    avoid_void_async: true
+    await_only_futures: true
+    camel_case_extensions: true
+    camel_case_types: true
+    cascade_invocations: true
+    cast_nullable_to_non_nullable: true
+    constant_identifier_names: true
+    curly_braces_in_flow_control_structures: true
+    deprecated_consistency: true
+    directives_ordering: true
+    do_not_use_environment: true
+    empty_catches: true
+    empty_constructor_bodies: true
+    eol_at_end_of_file: true
+    exhaustive_cases: true
+    file_names: true
+    flutter_style_todos: true
+    implementation_imports: true
+    join_return_with_assignment: true
+    leading_newlines_in_multiline_strings: true
+    library_names: true
+    library_prefixes: true
+    library_private_types_in_public_api: true
+    lines_longer_than_80_chars: true
+    missing_whitespace_between_adjacent_strings: true
+    no_default_cases: true
+    non_constant_identifier_names: true
+    noop_primitive_operations: true
+    null_check_on_nullable_type_parameter: true
+    null_closures: true
+    omit_local_variable_types: true
+    one_member_abstracts: true
+    only_throw_errors: true
+    overridden_fields: true
+    package_api_docs: true
+    package_prefixed_library_names: true
+    parameter_assignments: true
+    prefer_adjacent_string_concatenation: true
+    prefer_asserts_in_initializer_lists: true
+    prefer_asserts_with_message: true
+    prefer_collection_literals: true
+    prefer_conditional_assignment: true
+    prefer_const_constructors: false
+    prefer_const_constructors_in_immutables: true
+    prefer_const_declarations: false
+    prefer_const_literals_to_create_immutables: false
+    prefer_constructors_over_static_methods: true
+    prefer_contains: true
+    prefer_double_quotes: false
+    prefer_equal_for_default_values: true
+    prefer_expression_function_bodies: false
+    prefer_final_fields: true
+    prefer_final_in_for_each: true
+    prefer_final_locals: false
+    prefer_final_parameters: false
+    prefer_for_elements_to_map_fromIterable: true
+    prefer_foreach: true
+    prefer_function_declarations_over_variables: true
+    prefer_generic_function_type_aliases: true
+    prefer_if_elements_to_conditional_expressions: true
+    prefer_if_null_operators: true
+    prefer_initializing_formals: true
+    prefer_inlined_adds: true
+    prefer_int_literals: false
+    prefer_interpolation_to_compose_strings: true
+    prefer_is_empty: true
+    prefer_is_not_empty: true
+    prefer_is_not_operator: true
+    prefer_iterable_whereType: true
+    prefer_mixin: true
+    prefer_null_aware_method_calls: true
+    prefer_null_aware_operators: true
+    prefer_single_quotes: true
+    prefer_spread_collections: true
+    prefer_typing_uninitialized_variables: true
+    public_member_api_docs: false
+    recursive_getters: true
+    require_trailing_commas: true
+    sized_box_for_whitespace: true
+    slash_for_doc_comments: true
+    sort_child_properties_last: true
+    sort_constructors_first: true
+    sort_unnamed_constructors_first: true
+    tighten_type_of_initializing_formals: true
+    type_annotate_public_apis: true
+    type_init_formals: true
+    unawaited_futures: true
+    unnecessary_await_in_return: true
+    unnecessary_brace_in_string_interps: true
+    unnecessary_const: false
+    unnecessary_constructor_name: true
+    unnecessary_final: true
+    unnecessary_getters_setters: true
+    unnecessary_lambdas: true
+    unnecessary_new: true
+    unnecessary_null_aware_assignments: true
+    unnecessary_null_checks: true
+    unnecessary_null_in_if_null_operators: true
+    unnecessary_nullable_for_final_variable_declarations: true
+    unnecessary_overrides: true
+    unnecessary_parenthesis: true
+    unnecessary_raw_strings: true
+    unnecessary_string_escapes: true
+    unnecessary_string_interpolations: true
+    unnecessary_this: true
+    use_full_hex_values_for_flutter_colors: true
+    use_function_type_syntax_for_parameters: true
+    use_if_null_to_convert_nulls_to_bools: true
+    use_is_even_rather_than_modulo: true
+    use_late_for_private_fields_and_variables: true
+    use_named_constants: true
+    use_raw_strings: false
+    use_rethrow_when_possible: true
+    use_setters_to_change_properties: true
+    use_string_buffers: true
+    use_test_throws_matchers: true
+    use_to_and_as_if_applicable: true
+    void_checks: true
+    
 
 # Additional information about this file can be found at
 # https://dart.dev/guides/language/analysis-options

example/lib/controlled.dart

@@ -1,78 +0,0 @@
-import 'package:flutter/material.dart';
-
-main() {
-  runApp(MaterialApp(
-    home: Scaffold(
-      body: Center(
-        child: ControlledWidget(
-            initialString: 'old value',
-            onCreate: (controller) async {
-              Future.delayed(const Duration(seconds: 5), () {
-                controller.value = 'new value';
-              });
-            }),
-      ),
-    ),
-  ));
-}
-
-enum TimePrecision {
-  updateOnly,
-  everySecond,
-  everyMinute
-}
-
-class ControlledWidget extends StatefulWidget {
-  final void Function(MyController) onCreate;
-  final String? initialString;
-  final TimePrecision precision;
-  const ControlledWidget({
-    Key? key,
-    required this.onCreate,
-    this.initialString,
-    this.precision = TimePrecision.updateOnly,
-  }) : super(key: key);
-
-  @override
-  _ControlledWidgetState createState() => _ControlledWidgetState();
-}
-
-class _ControlledWidgetState extends State<ControlledWidget> {
-  late final MyController _controller;
-
-  @override
-  void initState() {
-    _controller = MyController(widget.initialString ?? '');
-    _controller.addListener(_onChange);
-    widget.onCreate(_controller);
-    super.initState();
-  }
-
-  void _onChange() {
-    setState(() {});
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    return Text(_controller.value);
-  }
-
-  @override
-  void dispose() {
-    _controller.dispose();
-    super.dispose();
-  }
-}
-
-class MyController extends ChangeNotifier {
-  String _currentString;
-
-  MyController(String initial) : _currentString = initial;
-
-  String get value => _currentString;
-
-  set value(String value) {
-    _currentString = value;
-    notifyListeners();
-  }
-}

example/lib/main.dart

@@ -2,7 +2,6 @@ import 'dart:async';
 import 'dart:math';
 
 import 'package:flutter/material.dart';
-import 'package:google_maps_flutter/google_maps_flutter.dart';
 import 'package:google_track_trace/google_track_trace.dart';
 
 class TrackTraceDemo extends StatefulWidget {
@@ -27,22 +26,25 @@ class _TrackTraceDemoState extends State<TrackTraceDemo> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-          title: (controller == null || controller!.route == null)
+        title: (controller == null || controller!.route == null)
-              ? const Text('TrackTrace example')
+            ? const Text('TrackTrace example')
-              : Text(controller!.route!.duration.toString() +
+            : Text(
-                  ' seconds, afstand: ' +
+                '${controller!.route!.duration} seconds, afstand: '
-                  (controller!.route!.distance / 1000).toString() +
+                '${controller!.route!.distance / 1000} km',
-                  ' km')),
+              ),
+      ),
       body: GoogleTrackTraceMap(
         startPosition: const Marker(
           markerId: MarkerId('Start locatie'),
           position: LatLng(52.356057, 4.897540),
         ),
         destinationPosition: const Marker(
-            markerId: MarkerId('Bestemming Locatie'),
+          markerId: MarkerId('Bestemming Locatie'),
-            position: LatLng(52.364709, 4.877157)),
+          position: LatLng(52.364709, 4.877157),
+        ),
         googleAPIKey: 'AIzaSyDaxZX8TeQeVf5tW-D6A66WLl20arbWV6c',
         travelMode: TravelMode.bicycling,
+        mapType: MapType.satellite,
         routeUpdateInterval: 60,
         timerPrecision: TimePrecision.everySecond,
         zoomGesturesEnabled: true,
@@ -66,15 +68,26 @@ class _TrackTraceDemoState extends State<TrackTraceDemo> {
     // 51.939909, 6.314950 SE
     if (controller != null) {
       controller!.start = Marker(
-          markerId: const MarkerId('Start Locatie'),
+        markerId: const MarkerId('Start Locatie'),
-          position: LatLng(51.93 + Random().nextDouble() * 0.06,
+        position: LatLng(
-              6.23 + Random().nextDouble() * 0.08));
+          51.93 + Random().nextDouble() * 0.06,
+          6.23 + Random().nextDouble() * 0.08,
+        ),
+      );
     }
   }
 
   void moveAlongRoute() {
-    if (controller != null && controller!.route != null && controller!.route!.line.length > 1) {
+    if (controller != null &&
-      controller!.start = Marker(markerId: const MarkerId('Start Locatie'), position: LatLng(controller!.route!.line[1].latitude, controller!.route!.line[1].longitude));
+        controller!.route != null &&
+        controller!.route!.line.length > 1) {
+      controller!.start = Marker(
+        markerId: const MarkerId('Start Locatie'),
+        position: LatLng(
+          controller!.route!.line[1].latitude,
+          controller!.route!.line[1].longitude,
+        ),
+      );
     }
   }
 }

lib/google_track_trace.dart

@@ -7,10 +7,13 @@ import 'dart:math';
 
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
-import 'package:google_maps_flutter/google_maps_flutter.dart';
 import 'package:flutter_polyline_points/flutter_polyline_points.dart';
+import 'package:google_maps_flutter/google_maps_flutter.dart';
 import 'package:http/http.dart' as http;
 
-part 'src/google_map.dart';
+export 'package:google_maps_flutter/google_maps_flutter.dart'
+    show MapType, Marker, MarkerId, Polyline, PolylineId, LatLng;
+
 part 'src/controller.dart';
-part 'src/directions_controller.dart';
+part 'src/directions_repository.dart';
+part 'src/google_map.dart';

lib/src/controller.dart

@@ -1,15 +1,15 @@
 part of google_track_trace;
 
 class TrackTraceController extends ChangeNotifier {
-  GoogleMapController? _mapController;
-  Marker _startPosition;
-  Marker _destinationPosition;
-  TrackTraceRoute? _route;
-
   TrackTraceController(Marker start, Marker destination)
       : _startPosition = start,
         _destinationPosition = destination;
 
+  GoogleMapController? mapController;
+  Marker _startPosition;
+  Marker _destinationPosition;
+  TrackTraceRoute? _route;
+
   set start(Marker start) {
     _startPosition = start;
     notifyListeners();
@@ -31,44 +31,25 @@ class TrackTraceController extends ChangeNotifier {
     notifyListeners();
   }
 
-  set mapController(GoogleMapController? controller) {
-    _mapController = controller;
-  }
-
-  GoogleMapController? get mapController => _mapController;
-
   @override
   void dispose() {
-    _mapController?.dispose();
+    mapController?.dispose();
     super.dispose();
   }
 }
 
 class TrackTraceRoute {
+TrackTraceRoute(
+      int durationValue, int distanceValue, List<PointLatLng> lineValue,)
+      : duration = durationValue,
+        distance = distanceValue,
+        line = lineValue;
   /// route duration in seconds
-  int _duration = 0;
+  int duration = 0;
 
   /// route distance in meters
-  int _distance = 0;
+  int distance = 0;
 
   /// route edge points
   final List<PointLatLng> line;
-
-  TrackTraceRoute(
-      int durationValue, int distanceValue, List<PointLatLng> lineValue)
-      : _duration = durationValue,
-        _distance = distanceValue,
-        line = lineValue;
-
-  int get distance => _distance;
-
-  int get duration => _duration;
-
-  set distance(int distance) {
-    _distance = distance;
-  }
-
-  set duration(int duration) {
-    _duration = duration;
-  }
 }

lib/src/directions_repository.dart

@@ -13,11 +13,10 @@ class DirectionsRepository {
     required String key,
   }) async {
     try {
-      final queryParameters = {
+      var queryParameters = {
         'origin': '${origin.latitude},${origin.longitude}',
         'destination': '${destination.latitude},${destination.longitude}',
-        'key':
+        'key': key, // get this key from the controller
-            key, // get this key from the controller
         'mode': <TravelMode, String>{
           TravelMode.driving: 'driving',
           TravelMode.bicycling: 'bicycling',
@@ -25,26 +24,25 @@ class DirectionsRepository {
           TravelMode.walking: 'walking',
         }[mode],
       };
-      final uri = Uri.https('maps.googleapis.com', _baseUrl, queryParameters);
+      var uri = Uri.https('maps.googleapis.com', _baseUrl, queryParameters);
-      final response = await http.get(uri, headers: {
+      var response = await http.get(
-        HttpHeaders.contentTypeHeader: 'application/json',
+        uri,
-      });
+        headers: {
+          HttpHeaders.contentTypeHeader: 'application/json',
+        },
+      );
       if (response.statusCode == 200) {
         return Directions.fromMap(jsonDecode(response.body));
       }
     } on HttpException catch (e) {
-      print(e.message);
+      debugPrint(e.message);
     }
-    throw GoogleMapsException('Unable to retrieve directions from Google Maps API');
+    throw GoogleMapsException(
+        'Unable to retrieve directions from Google Maps API',);
   }
 }
 
 class Directions {
-  final LatLngBounds bounds;
-  final List<PointLatLng> polylinePoints;
-  final int totalDistance;
-  final int totalDuration;
-
   const Directions({
     required this.bounds,
     required this.polylinePoints,
@@ -58,19 +56,19 @@ class Directions {
       throw GoogleMapsException('No Routes available');
     }
 
-    final data = Map<String, dynamic>.from(map['routes'][0]);
+    var data = Map<String, dynamic>.from((map['routes'] as List)[0]);
 
-    final northeast = data['bounds']['northeast'];
+    var northeast = data['bounds']['northeast'];
-    final southwest = data['bounds']['southwest'];
+    var southwest = data['bounds']['southwest'];
-    final bounds = LatLngBounds(
+    var bounds = LatLngBounds(
       southwest: LatLng(southwest['lat'], southwest['lng']),
       northeast: LatLng(northeast['lat'], northeast['lng']),
     );
 
-    int distance = 0;
+    var distance = 0;
-    int duration = 0;
+    var duration = 0;
     if ((data['legs'] as List).isNotEmpty) {
-      final leg = data['legs'][0];
+      var leg = (data['legs'] as List)[0];
       distance = leg['distance']['value'];
       duration = leg['duration']['value'];
     }
@@ -83,6 +81,11 @@ class Directions {
       totalDuration: duration,
     );
   }
+
+  final LatLngBounds bounds;
+  final List<PointLatLng> polylinePoints;
+  final int totalDistance;
+  final int totalDuration;
 }
 
 class GoogleMapsException implements Exception {

lib/src/google_map.dart

@@ -4,13 +4,13 @@ part of google_track_trace;
 enum TimePrecision { updateOnly, everySecond, everyMinute }
 
 class GoogleTrackTraceMap extends StatefulWidget {
-  GoogleTrackTraceMap({
+  const GoogleTrackTraceMap({
-    Key? key,
     required this.onMapCreated,
     required this.startPosition,
     required this.destinationPosition,
     required this.googleAPIKey,
     required this.routeUpdateInterval,
+    Key? key,
     this.timerPrecision = TimePrecision.everyMinute,
     this.travelMode = TravelMode.driving,
     this.compassEnabled = false,
@@ -22,8 +22,7 @@ class GoogleTrackTraceMap extends StatefulWidget {
     this.mapMarkations =
         '[{"featureType": "poi","stylers": [{"visibility": "off"}]}]',
     this.line,
-  })  : assert(true),
+  })  : super(key: key);
-        super(key: key);
 
   /// Callback method for when the map is ready to be used.
   ///
@@ -40,7 +39,7 @@ class GoogleTrackTraceMap extends StatefulWidget {
   final Marker startPosition;
   final Marker destinationPosition;
 
-  Polyline? line;
+  final Polyline? line;
 
   final bool compassEnabled;
   final bool zoomControlsEnabled;
@@ -51,11 +50,6 @@ class GoogleTrackTraceMap extends StatefulWidget {
 
   final String mapMarkations;
 
-  CameraPosition initialCameraPosition = const CameraPosition(
-      // doetinchem default initialCamera
-      target: LatLng(51.965578, 6.293439),
-      zoom: 12.0);
-
   final String googleAPIKey;
 
   @override
@@ -88,7 +82,7 @@ class _GoogleTrackTraceMapState extends State<GoogleTrackTraceMap> {
   Widget build(BuildContext context) {
     return GoogleMap(
         initialCameraPosition: calculateCameraPosition(
-            controller.start.position, controller.end.position),
+            controller.start.position, controller.end.position,),
         onMapCreated: _onMapCreated,
         compassEnabled: widget.compassEnabled,
         zoomControlsEnabled: widget.zoomControlsEnabled,
@@ -96,27 +90,27 @@ class _GoogleTrackTraceMapState extends State<GoogleTrackTraceMap> {
         mapToolbarEnabled: widget.mapToolbarEnabled,
         mapType: widget.mapType,
         buildingsEnabled: widget.buildingsEnabled,
-        markers: {
+        markers: <Marker>{
           controller.start,
           controller.end,
         },
-        polylines: {
+        polylines: <Polyline>{
           if (controller.route != null)
             (widget.line != null)
                 ? widget.line!.copyWith(
                     pointsParam: controller.route!.line
-                        .map((e) => LatLng(e.latitude, e.longitude))
+                        .map((PointLatLng e) => LatLng(e.latitude, e.longitude))
-                        .toList())
+                        .toList(),)
                 : Polyline(
                     // default PolyLine if none is provided
                     polylineId: const PolylineId('track&trace route'),
                     color: Theme.of(context).primaryColor,
                     width: 4,
                     points: controller.route!.line
-                        .map((e) => LatLng(e.latitude, e.longitude))
+                        .map((PointLatLng e) => LatLng(e.latitude, e.longitude))
                         .toList(),
                   ),
-        });
+        },);
   }
 
   void _onChange() {
@@ -131,12 +125,17 @@ class _GoogleTrackTraceMapState extends State<GoogleTrackTraceMap> {
   }
 
   CameraPosition calculateCameraPosition(LatLng pointA, LatLng pointB) {
-    LatLng target = LatLng((pointA.latitude + pointB.latitude) / 2,
+    var target = LatLng(
-        (pointA.longitude + pointB.longitude) / 2);
+      (pointA.latitude + pointB.latitude) / 2,
-    double calculatedZoom = 13.0; // TODO calculate this zoom
+      (pointA.longitude + pointB.longitude) / 2,
+    );
 
     return CameraPosition(
-        target: target, zoom: calculatedZoom, tilt: 0.0, bearing: 0.0);
+      target: target,
+      zoom: 13.0,
+      tilt: 0.0,
+      bearing: 0.0,
+    );
   }
 
   CameraUpdate moveCameraToCenter(LatLng pointA, LatLng pointB) {
@@ -151,33 +150,34 @@ class _GoogleTrackTraceMapState extends State<GoogleTrackTraceMap> {
             max(pointA.longitude, pointB.longitude),
           ),
         ),
-        50);
+        50,);
   }
 
   void startRouteUpdateTimer() {
     calculateRoute(); // run at the start
-    Timer.periodic(Duration(seconds: widget.routeUpdateInterval), (timer) {
+    Timer.periodic(Duration(seconds: widget.routeUpdateInterval), 
+    (Timer timer) {
       calculateRoute();
     });
   }
 
   void startMarkerUpdateTimer() {
     if (widget.timerPrecision != TimePrecision.updateOnly) {
-      int updateInterval =
+      var updateInterval =
           (widget.timerPrecision == TimePrecision.everyMinute) ? 60 : 1;
       Timer.periodic(Duration(seconds: updateInterval), (timer) {
         if (controller.route != null) {
           controller.route = TrackTraceRoute(
               controller.route!.duration - updateInterval,
               controller.route!.distance,
-              controller.route!.line);
+              controller.route!.line,);
         }
       });
     }
   }
 
-  void calculateRoute() async {
+  void calculateRoute(){
-    DirectionsRepository() //TODO refactor this away
+    DirectionsRepository() // TODO(freek): refactor this away
         .getDirections(
           origin: controller.start.position,
           destination: controller.end.position,
@@ -186,15 +186,15 @@ class _GoogleTrackTraceMapState extends State<GoogleTrackTraceMap> {
         )
         .then((value) => {
               controller.route = TrackTraceRoute(value.totalDuration,
-                  value.totalDistance, value.polylinePoints),
+                  value.totalDistance, value.polylinePoints,),
               if (controller.mapController != null)
                 {
                   controller.mapController!.moveCamera(moveCameraToCenter(
-                      controller.start.position, controller.end.position)),
+                      controller.start.position, controller.end.position,),),
                 },
               setState(() {
                 lastRouteUpdate = DateTime.now();
               })
-            });
+            },);
   }
 }