Place tracker/maintenance (#519)

* format place_tracker README

* update sentence in README

* sort Dart members, remove unnecessary type declarations

* Run place_tracker on Android and iOS, update project files

* add link to developer preview caveat

* grammar

* update MAINTENANCE

place_tracker/lib/place_map.dart

@@ -11,41 +11,55 @@ import 'place.dart';
 import 'place_details.dart';
 import 'place_tracker_app.dart';
 
+class MapConfiguration {
+  final List<Place> places;
+
+  final PlaceCategory selectedCategory;
+  const MapConfiguration({
+    @required this.places,
+    @required this.selectedCategory,
+  })  : assert(places != null),
+        assert(selectedCategory != null);
+
+  @override
+  int get hashCode => places.hashCode ^ selectedCategory.hashCode;
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(this, other)) {
+      return true;
+    }
+
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+
+    return other is MapConfiguration &&
+        other.places == places &&
+        other.selectedCategory == selectedCategory;
+  }
+
+  static MapConfiguration of(AppState appState) {
+    return MapConfiguration(
+      places: appState.places,
+      selectedCategory: appState.selectedCategory,
+    );
+  }
+}
+
 class PlaceMap extends StatefulWidget {
+  final LatLng center;
+
   const PlaceMap({
     Key key,
     this.center,
   }) : super(key: key);
 
-  final LatLng center;
-
   @override
   PlaceMapState createState() => PlaceMapState();
 }
 
 class PlaceMapState extends State<PlaceMap> {
-  static Future<BitmapDescriptor> _getPlaceMarkerIcon(
-      BuildContext context, PlaceCategory category) async {
-    switch (category) {
-      case PlaceCategory.favorite:
-        return BitmapDescriptor.fromAssetImage(
-            createLocalImageConfiguration(context), 'assets/heart.png');
-        break;
-      case PlaceCategory.visited:
-        return BitmapDescriptor.fromAssetImage(
-            createLocalImageConfiguration(context), 'assets/visited.png');
-        break;
-      case PlaceCategory.wantToGo:
-      default:
-        return BitmapDescriptor.defaultMarker;
-    }
-  }
-
-  static List<Place> _getPlacesForCategory(
-      PlaceCategory category, List<Place> places) {
-    return places.where((place) => place.category == category).toList();
-  }
-
   Completer<GoogleMapController> mapController = Completer();
 
   MapType _currentMapType = MapType.normal;
@@ -60,6 +74,50 @@ class PlaceMapState extends State<PlaceMap> {
 
   MapConfiguration _configuration;
 
+  @override
+  Widget build(BuildContext context) {
+    _maybeUpdateMapConfiguration();
+    var state = Provider.of<AppState>(context);
+
+    return Builder(builder: (context) {
+      // We need this additional builder here so that we can pass its context to
+      // _AddPlaceButtonBar's onSavePressed callback. This callback shows a
+      // SnackBar and to do this, we need a build context that has Scaffold as
+      // an ancestor.
+      return Center(
+        child: Stack(
+          children: [
+            GoogleMap(
+              onMapCreated: onMapCreated,
+              initialCameraPosition: CameraPosition(
+                target: widget.center,
+                zoom: 11.0,
+              ),
+              mapType: _currentMapType,
+              markers: _markers,
+              onCameraMove: (position) => _lastMapPosition = position.target,
+            ),
+            _CategoryButtonBar(
+              selectedPlaceCategory: state.selectedCategory,
+              visible: _pendingMarker == null,
+              onChanged: _switchSelectedCategory,
+            ),
+            _AddPlaceButtonBar(
+              visible: _pendingMarker != null,
+              onSavePressed: () => _confirmAddPlace(context),
+              onCancelPressed: _cancelAddPlace,
+            ),
+            _MapFabs(
+              visible: _pendingMarker == null,
+              onAddPlacePressed: _onAddPlacePressed,
+              onToggleMapTypePressed: _onToggleMapTypePressed,
+            ),
+          ],
+        ),
+      );
+    });
+  }
+
   Future<void> onMapCreated(GoogleMapController controller) async {
     mapController.complete(controller);
     _lastMapPosition = widget.center;
@@ -83,152 +141,13 @@ class PlaceMapState extends State<PlaceMap> {
     );
   }
 
-  Future<Marker> _createPlaceMarker(BuildContext context, Place place) async {
-    final marker = Marker(
-      markerId: MarkerId(place.latLng.toString()),
-      position: place.latLng,
-      infoWindow: InfoWindow(
-        title: place.name,
-        snippet: '${place.starRating} Star Rating',
-        onTap: () => _pushPlaceDetailsScreen(place),
-      ),
-      icon: await _getPlaceMarkerIcon(context, place.category),
-      visible: place.category ==
-          Provider.of<AppState>(context, listen: false).selectedCategory,
-    );
-    _markedPlaces[marker] = place;
-    return marker;
-  }
-
-  void _pushPlaceDetailsScreen(Place place) {
-    assert(place != null);
-
-    Navigator.push<void>(
-      context,
-      MaterialPageRoute(builder: (context) {
-        return PlaceDetails(
-          place: place,
-          onChanged: (value) => _onPlaceChanged(value),
-        );
-      }),
-    );
-  }
-
-  void _onPlaceChanged(Place value) {
-    // Replace the place with the modified version.
-    final newPlaces =
-        List<Place>.from(Provider.of<AppState>(context, listen: false).places);
-    final index = newPlaces.indexWhere((place) => place.id == value.id);
-    newPlaces[index] = value;
-
-    _updateExistingPlaceMarker(place: value);
-
-    // Manually update our map configuration here since our map is already
-    // updated with the new marker. Otherwise, the map would be reconfigured
-    // in the main build method due to a modified AppState.
-    _configuration = MapConfiguration(
-      places: newPlaces,
-      selectedCategory:
-          Provider.of<AppState>(context, listen: false).selectedCategory,
-    );
-
-    Provider.of<AppState>(context, listen: false).setPlaces(newPlaces);
-  }
-
-  void _updateExistingPlaceMarker({@required Place place}) {
-    var marker = _markedPlaces.keys
-        .singleWhere((value) => _markedPlaces[value].id == place.id);
-
-    setState(() {
-      final updatedMarker = marker.copyWith(
-        infoWindowParam: InfoWindow(
-          title: place.name,
-          snippet:
-              place.starRating != 0 ? '${place.starRating} Star Rating' : null,
-        ),
-      );
-      _updateMarker(marker: marker, updatedMarker: updatedMarker, place: place);
-    });
-  }
-
-  void _updateMarker({
-    @required Marker marker,
-    @required Marker updatedMarker,
-    @required Place place,
-  }) {
-    _markers.remove(marker);
-    _markedPlaces.remove(marker);
-
-    _markers.add(updatedMarker);
-    _markedPlaces[updatedMarker] = place;
-  }
-
-  Future<void> _switchSelectedCategory(PlaceCategory category) async {
-    Provider.of<AppState>(context, listen: false).setSelectedCategory(category);
-    await _showPlacesForSelectedCategory(category);
-  }
-
-  Future<void> _showPlacesForSelectedCategory(PlaceCategory category) async {
-    setState(() {
-      for (var marker in List.of(_markedPlaces.keys)) {
-        final place = _markedPlaces[marker];
-        final updatedMarker = marker.copyWith(
-          visibleParam: place.category == category,
-        );
-
-        _updateMarker(
-          marker: marker,
-          updatedMarker: updatedMarker,
-          place: place,
-        );
-      }
-    });
-
-    await _zoomToFitPlaces(_getPlacesForCategory(
-      category,
-      _markedPlaces.values.toList(),
-    ));
-  }
-
-  Future<void> _zoomToFitPlaces(List<Place> places) async {
-    var controller = await mapController.future;
-
-    // Default min/max values to latitude and longitude of center.
-    var minLat = widget.center.latitude;
-    var maxLat = widget.center.latitude;
-    var minLong = widget.center.longitude;
-    var maxLong = widget.center.longitude;
-
-    for (var place in places) {
-      minLat = min(minLat, place.latitude);
-      maxLat = max(maxLat, place.latitude);
-      minLong = min(minLong, place.longitude);
-      maxLong = max(maxLong, place.longitude);
+  void _cancelAddPlace() {
+    if (_pendingMarker != null) {
+      setState(() {
+        _markers.remove(_pendingMarker);
+        _pendingMarker = null;
+      });
     }
-
-    await controller.animateCamera(
-      CameraUpdate.newLatLngBounds(
-        LatLngBounds(
-          southwest: LatLng(minLat, minLong),
-          northeast: LatLng(maxLat, maxLong),
-        ),
-        48.0,
-      ),
-    );
-  }
-
-  Future<void> _onAddPlacePressed() async {
-    setState(() {
-      final newMarker = Marker(
-        markerId: MarkerId(_lastMapPosition.toString()),
-        position: _lastMapPosition,
-        infoWindow: InfoWindow(title: 'New Place'),
-        draggable: true,
-        icon: BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueGreen),
-      );
-      _markers.add(newMarker);
-      _pendingMarker = newMarker;
-    });
   }
 
   Future<void> _confirmAddPlace(BuildContext context) async {
@@ -298,22 +217,21 @@ class PlaceMapState extends State<PlaceMap> {
     }
   }
 
-  void _cancelAddPlace() {
-    if (_pendingMarker != null) {
-      setState(() {
-        _markers.remove(_pendingMarker);
-        _pendingMarker = null;
-      });
-    }
-  }
-
-  void _onToggleMapTypePressed() {
-    final nextType =
-        MapType.values[(_currentMapType.index + 1) % MapType.values.length];
-
-    setState(() {
-      _currentMapType = nextType;
-    });
+  Future<Marker> _createPlaceMarker(BuildContext context, Place place) async {
+    final marker = Marker(
+      markerId: MarkerId(place.latLng.toString()),
+      position: place.latLng,
+      infoWindow: InfoWindow(
+        title: place.name,
+        snippet: '${place.starRating} Star Rating',
+        onTap: () => _pushPlaceDetailsScreen(place),
+      ),
+      icon: await _getPlaceMarkerIcon(context, place.category),
+      visible: place.category ==
+          Provider.of<AppState>(context, listen: false).selectedCategory,
+    );
+    _markedPlaces[marker] = place;
+    return marker;
   }
 
   Future<void> _maybeUpdateMapConfiguration() async {
@@ -351,65 +269,183 @@ class PlaceMapState extends State<PlaceMap> {
     }
   }
 
-  @override
-  Widget build(BuildContext context) {
-    _maybeUpdateMapConfiguration();
-    var state = Provider.of<AppState>(context);
+  Future<void> _onAddPlacePressed() async {
+    setState(() {
+      final newMarker = Marker(
+        markerId: MarkerId(_lastMapPosition.toString()),
+        position: _lastMapPosition,
+        infoWindow: InfoWindow(title: 'New Place'),
+        draggable: true,
+        icon: BitmapDescriptor.defaultMarkerWithHue(BitmapDescriptor.hueGreen),
+      );
+      _markers.add(newMarker);
+      _pendingMarker = newMarker;
+    });
+  }
 
-    return Builder(builder: (context) {
-      // We need this additional builder here so that we can pass its context to
-      // _AddPlaceButtonBar's onSavePressed callback. This callback shows a
-      // SnackBar and to do this, we need a build context that has Scaffold as
-      // an ancestor.
-      return Center(
-        child: Stack(
-          children: <Widget>[
-            GoogleMap(
-              onMapCreated: onMapCreated,
-              initialCameraPosition: CameraPosition(
-                target: widget.center,
-                zoom: 11.0,
-              ),
-              mapType: _currentMapType,
-              markers: _markers,
-              onCameraMove: (position) => _lastMapPosition = position.target,
-            ),
-            _CategoryButtonBar(
-              selectedPlaceCategory: state.selectedCategory,
-              visible: _pendingMarker == null,
-              onChanged: _switchSelectedCategory,
-            ),
-            _AddPlaceButtonBar(
-              visible: _pendingMarker != null,
-              onSavePressed: () => _confirmAddPlace(context),
-              onCancelPressed: _cancelAddPlace,
-            ),
-            _MapFabs(
-              visible: _pendingMarker == null,
-              onAddPlacePressed: _onAddPlacePressed,
-              onToggleMapTypePressed: _onToggleMapTypePressed,
-            ),
-          ],
+  void _onPlaceChanged(Place value) {
+    // Replace the place with the modified version.
+    final newPlaces =
+        List<Place>.from(Provider.of<AppState>(context, listen: false).places);
+    final index = newPlaces.indexWhere((place) => place.id == value.id);
+    newPlaces[index] = value;
+
+    _updateExistingPlaceMarker(place: value);
+
+    // Manually update our map configuration here since our map is already
+    // updated with the new marker. Otherwise, the map would be reconfigured
+    // in the main build method due to a modified AppState.
+    _configuration = MapConfiguration(
+      places: newPlaces,
+      selectedCategory:
+          Provider.of<AppState>(context, listen: false).selectedCategory,
+    );
+
+    Provider.of<AppState>(context, listen: false).setPlaces(newPlaces);
+  }
+
+  void _onToggleMapTypePressed() {
+    final nextType =
+        MapType.values[(_currentMapType.index + 1) % MapType.values.length];
+
+    setState(() {
+      _currentMapType = nextType;
+    });
+  }
+
+  void _pushPlaceDetailsScreen(Place place) {
+    assert(place != null);
+
+    Navigator.push<void>(
+      context,
+      MaterialPageRoute(builder: (context) {
+        return PlaceDetails(
+          place: place,
+          onChanged: (value) => _onPlaceChanged(value),
+        );
+      }),
+    );
+  }
+
+  Future<void> _showPlacesForSelectedCategory(PlaceCategory category) async {
+    setState(() {
+      for (var marker in List.of(_markedPlaces.keys)) {
+        final place = _markedPlaces[marker];
+        final updatedMarker = marker.copyWith(
+          visibleParam: place.category == category,
+        );
+
+        _updateMarker(
+          marker: marker,
+          updatedMarker: updatedMarker,
+          place: place,
+        );
+      }
+    });
+
+    await _zoomToFitPlaces(_getPlacesForCategory(
+      category,
+      _markedPlaces.values.toList(),
+    ));
+  }
+
+  Future<void> _switchSelectedCategory(PlaceCategory category) async {
+    Provider.of<AppState>(context, listen: false).setSelectedCategory(category);
+    await _showPlacesForSelectedCategory(category);
+  }
+
+  void _updateExistingPlaceMarker({@required Place place}) {
+    var marker = _markedPlaces.keys
+        .singleWhere((value) => _markedPlaces[value].id == place.id);
+
+    setState(() {
+      final updatedMarker = marker.copyWith(
+        infoWindowParam: InfoWindow(
+          title: place.name,
+          snippet:
+              place.starRating != 0 ? '${place.starRating} Star Rating' : null,
         ),
       );
+      _updateMarker(marker: marker, updatedMarker: updatedMarker, place: place);
     });
   }
+
+  void _updateMarker({
+    @required Marker marker,
+    @required Marker updatedMarker,
+    @required Place place,
+  }) {
+    _markers.remove(marker);
+    _markedPlaces.remove(marker);
+
+    _markers.add(updatedMarker);
+    _markedPlaces[updatedMarker] = place;
+  }
+
+  Future<void> _zoomToFitPlaces(List<Place> places) async {
+    var controller = await mapController.future;
+
+    // Default min/max values to latitude and longitude of center.
+    var minLat = widget.center.latitude;
+    var maxLat = widget.center.latitude;
+    var minLong = widget.center.longitude;
+    var maxLong = widget.center.longitude;
+
+    for (var place in places) {
+      minLat = min(minLat, place.latitude);
+      maxLat = max(maxLat, place.latitude);
+      minLong = min(minLong, place.longitude);
+      maxLong = max(maxLong, place.longitude);
+    }
+
+    await controller.animateCamera(
+      CameraUpdate.newLatLngBounds(
+        LatLngBounds(
+          southwest: LatLng(minLat, minLong),
+          northeast: LatLng(maxLat, maxLong),
+        ),
+        48.0,
+      ),
+    );
+  }
+
+  static Future<BitmapDescriptor> _getPlaceMarkerIcon(
+      BuildContext context, PlaceCategory category) async {
+    switch (category) {
+      case PlaceCategory.favorite:
+        return BitmapDescriptor.fromAssetImage(
+            createLocalImageConfiguration(context), 'assets/heart.png');
+        break;
+      case PlaceCategory.visited:
+        return BitmapDescriptor.fromAssetImage(
+            createLocalImageConfiguration(context), 'assets/visited.png');
+        break;
+      case PlaceCategory.wantToGo:
+      default:
+        return BitmapDescriptor.defaultMarker;
+    }
+  }
+
+  static List<Place> _getPlacesForCategory(
+      PlaceCategory category, List<Place> places) {
+    return places.where((place) => place.category == category).toList();
+  }
 }
 
-class _CategoryButtonBar extends StatelessWidget {
-  const _CategoryButtonBar({
-    Key key,
-    @required this.selectedPlaceCategory,
-    @required this.visible,
-    @required this.onChanged,
-  })  : assert(selectedPlaceCategory != null),
-        assert(visible != null),
-        assert(onChanged != null),
-        super(key: key);
-
-  final PlaceCategory selectedPlaceCategory;
+class _AddPlaceButtonBar extends StatelessWidget {
   final bool visible;
-  final ValueChanged<PlaceCategory> onChanged;
+
+  final VoidCallback onSavePressed;
+  final VoidCallback onCancelPressed;
+  const _AddPlaceButtonBar({
+    Key key,
+    @required this.visible,
+    @required this.onSavePressed,
+    @required this.onCancelPressed,
+  })  : assert(visible != null),
+        assert(onSavePressed != null),
+        assert(onCancelPressed != null),
+        super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -420,7 +456,55 @@ class _CategoryButtonBar extends StatelessWidget {
         alignment: Alignment.bottomCenter,
         child: ButtonBar(
           alignment: MainAxisAlignment.center,
-          children: <Widget>[
+          children: [
+            RaisedButton(
+              color: Colors.blue,
+              child: const Text(
+                'Save',
+                style: TextStyle(color: Colors.white, fontSize: 16.0),
+              ),
+              onPressed: onSavePressed,
+            ),
+            RaisedButton(
+              color: Colors.red,
+              child: const Text(
+                'Cancel',
+                style: TextStyle(color: Colors.white, fontSize: 16.0),
+              ),
+              onPressed: onCancelPressed,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _CategoryButtonBar extends StatelessWidget {
+  final PlaceCategory selectedPlaceCategory;
+  final bool visible;
+  final ValueChanged<PlaceCategory> onChanged;
+
+  const _CategoryButtonBar({
+    Key key,
+    @required this.selectedPlaceCategory,
+    @required this.visible,
+    @required this.onChanged,
+  })  : assert(selectedPlaceCategory != null),
+        assert(visible != null),
+        assert(onChanged != null),
+        super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Visibility(
+      visible: visible,
+      child: Container(
+        padding: const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 14.0),
+        alignment: Alignment.bottomCenter,
+        child: ButtonBar(
+          alignment: MainAxisAlignment.center,
+          children: [
             RaisedButton(
               color: selectedPlaceCategory == PlaceCategory.favorite
                   ? Colors.green[700]
@@ -458,55 +542,11 @@ class _CategoryButtonBar extends StatelessWidget {
   }
 }
 
-class _AddPlaceButtonBar extends StatelessWidget {
-  const _AddPlaceButtonBar({
-    Key key,
-    @required this.visible,
-    @required this.onSavePressed,
-    @required this.onCancelPressed,
-  })  : assert(visible != null),
-        assert(onSavePressed != null),
-        assert(onCancelPressed != null),
-        super(key: key);
-
-  final bool visible;
-  final VoidCallback onSavePressed;
-  final VoidCallback onCancelPressed;
-
-  @override
-  Widget build(BuildContext context) {
-    return Visibility(
-      visible: visible,
-      child: Container(
-        padding: const EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 14.0),
-        alignment: Alignment.bottomCenter,
-        child: ButtonBar(
-          alignment: MainAxisAlignment.center,
-          children: <Widget>[
-            RaisedButton(
-              color: Colors.blue,
-              child: const Text(
-                'Save',
-                style: TextStyle(color: Colors.white, fontSize: 16.0),
-              ),
-              onPressed: onSavePressed,
-            ),
-            RaisedButton(
-              color: Colors.red,
-              child: const Text(
-                'Cancel',
-                style: TextStyle(color: Colors.white, fontSize: 16.0),
-              ),
-              onPressed: onCancelPressed,
-            ),
-          ],
-        ),
-      ),
-    );
-  }
-}
-
 class _MapFabs extends StatelessWidget {
+  final bool visible;
+  final VoidCallback onAddPlacePressed;
+  final VoidCallback onToggleMapTypePressed;
+
   const _MapFabs({
     Key key,
     @required this.visible,
@@ -517,10 +557,6 @@ class _MapFabs extends StatelessWidget {
         assert(onToggleMapTypePressed != null),
         super(key: key);
 
-  final bool visible;
-  final VoidCallback onAddPlacePressed;
-  final VoidCallback onToggleMapTypePressed;
-
   @override
   Widget build(BuildContext context) {
     return Container(
@@ -529,7 +565,7 @@ class _MapFabs extends StatelessWidget {
       child: Visibility(
         visible: visible,
         child: Column(
-          children: <Widget>[
+          children: [
             FloatingActionButton(
               heroTag: 'add_place_button',
               onPressed: onAddPlacePressed,
@@ -552,39 +588,3 @@ class _MapFabs extends StatelessWidget {
     );
   }
 }
-
-class MapConfiguration {
-  const MapConfiguration({
-    @required this.places,
-    @required this.selectedCategory,
-  })  : assert(places != null),
-        assert(selectedCategory != null);
-
-  final List<Place> places;
-  final PlaceCategory selectedCategory;
-
-  @override
-  int get hashCode => places.hashCode ^ selectedCategory.hashCode;
-
-  @override
-  bool operator ==(Object other) {
-    if (identical(this, other)) {
-      return true;
-    }
-
-    if (other.runtimeType != runtimeType) {
-      return false;
-    }
-
-    return other is MapConfiguration &&
-        other.places == places &&
-        other.selectedCategory == selectedCategory;
-  }
-
-  static MapConfiguration of(AppState appState) {
-    return MapConfiguration(
-      places: appState.places,
-      selectedCategory: appState.selectedCategory,
-    );
-  }
-}