quick country reverse geolocation w/o play services

lib/geo/countries.dart

@@ -0,0 +1,95 @@
+import 'dart:async';
+
+import 'package:aves/geo/topojson.dart';
+import 'package:country_code/country_code.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+import 'package:latlong/latlong.dart';
+
+final CountryTopology countryTopology = CountryTopology._private();
+
+class CountryTopology {
+  static const topoJsonAsset = 'assets/countries-50m.json';
+
+  CountryTopology._private();
+
+  Topology _topology;
+
+  Future<Topology> getTopology() => _topology != null ? SynchronousFuture(_topology) : rootBundle.loadString(topoJsonAsset).then(TopoJson().parse);
+
+  // return the country containing given coordinates
+  Future<CountryCode> countryCode(LatLng position) async {
+    return _countryOfNumeric(await numericCode(position));
+  }
+
+  // return the ISO 3166-1 numeric code of the country containing given coordinates
+  Future<int> numericCode(LatLng position) async {
+    final topology = await getTopology();
+    if (topology == null) return null;
+
+    final countries = (topology.objects['countries'] as GeometryCollection).geometries;
+    return _getNumeric(topology, countries, position);
+  }
+
+  // return a map of the given positions by country
+  Future<Map<CountryCode, Set<LatLng>>> countryCodeMap(Set<LatLng> positions) async {
+    final numericMap = await numericCodeMap(positions);
+    numericMap.remove(null);
+    final codeMap = numericMap.map((key, value) {
+      final code = _countryOfNumeric(key);
+      return code == null ? null : MapEntry(code, value);
+    });
+    codeMap.remove(null);
+    return codeMap;
+  }
+
+  // return a map of the given positions by the ISO 3166-1 numeric code of the country containing them
+  Future<Map<int, Set<LatLng>>> numericCodeMap(Set<LatLng> positions) async {
+    final topology = await getTopology();
+    if (topology == null) return null;
+
+    return compute(_isoNumericCodeMap, _IsoNumericCodeMapData(topology, positions));
+  }
+
+  static Future<Map<int, Set<LatLng>>> _isoNumericCodeMap(_IsoNumericCodeMapData data) async {
+    try {
+      final topology = data.topology;
+      final countries = (topology.objects['countries'] as GeometryCollection).geometries;
+      final byCode = <int, Set<LatLng>>{};
+      for (final position in data.positions) {
+        final code = _getNumeric(topology, countries, position);
+        byCode[code] = (byCode[code] ?? {})..add(position);
+      }
+      return byCode;
+    } catch (error, stack) {
+      // an unhandled error in a spawn isolate would make the app crash
+      debugPrint('failed to get country codes with error=$error\n$stack');
+    }
+    return null;
+  }
+
+  static int _getNumeric(Topology topology, List<Geometry> countries, LatLng position) {
+    final point = [position.longitude, position.latitude];
+    final hit = countries.firstWhere((country) => country.containsPoint(topology, point), orElse: () => null);
+    final idString = (hit?.id as String);
+    final code = idString == null ? null : int.tryParse(idString);
+    return code;
+  }
+
+  static CountryCode _countryOfNumeric(int numeric) {
+    if (numeric == null) return null;
+    try {
+      return CountryCode.ofNumeric(numeric);
+    } catch (error) {
+      debugPrint('failed to find country for numeric=$numeric with error=$error');
+    }
+    return null;
+  }
+}
+
+class _IsoNumericCodeMapData {
+  Topology topology;
+  Set<LatLng> positions;
+
+  _IsoNumericCodeMapData(this.topology, this.positions);
+}

lib/geo/topojson.dart

@@ -0,0 +1,245 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+
+// cf https://github.com/topojson/topojson-specification
+class TopoJson {
+  Future<Topology> parse(String data) async {
+    return compute(_isoParse, data);
+  }
+
+  static Topology _isoParse(String jsonData) {
+    try {
+      final data = json.decode(jsonData) as Map<String, dynamic>;
+      return Topology.parse(data);
+    } catch (error, stack) {
+      // an unhandled error in a spawn isolate would make the app crash
+      debugPrint('failed to parse TopoJSON with error=$error\n$stack');
+    }
+    return null;
+  }
+}
+
+enum TopoJsonObjectType { topology, point, multipoint, linestring, multilinestring, polygon, multipolygon, geometrycollection }
+
+TopoJsonObjectType _parseTopoJsonObjectType(String data) {
+  switch (data) {
+    case 'Topology':
+      return TopoJsonObjectType.topology;
+    case 'Point':
+      return TopoJsonObjectType.point;
+    case 'MultiPoint':
+      return TopoJsonObjectType.multipoint;
+    case 'LineString':
+      return TopoJsonObjectType.linestring;
+    case 'MultiLineString':
+      return TopoJsonObjectType.multilinestring;
+    case 'Polygon':
+      return TopoJsonObjectType.polygon;
+    case 'MultiPolygon':
+      return TopoJsonObjectType.multipolygon;
+    case 'GeometryCollection':
+      return TopoJsonObjectType.geometrycollection;
+  }
+  return null;
+}
+
+class TopologyJsonObject {
+  final List<num> bbox;
+
+  TopologyJsonObject.parse(Map<String, dynamic> data) : bbox = data.containsKey('bbox') ? (data['bbox'] as List).cast<num>().toList() : null;
+}
+
+class Topology extends TopologyJsonObject {
+  final Map<String, Geometry> objects;
+  final List<List<List<num>>> arcs;
+  final Transform transform;
+
+  Topology.parse(Map<String, dynamic> data)
+      : objects = (data['objects'] as Map).cast<String, dynamic>().map<String, Geometry>((name, geometry) => MapEntry(name, Geometry.build(geometry))),
+        arcs = (data['arcs'] as List).cast<List>().map((arc) => arc.cast<List>().map((position) => position.cast<num>()).toList()).toList(),
+        transform = data.containsKey('transform') ? Transform.parse((data['transform'] as Map).cast<String, dynamic>()) : null,
+        super.parse(data);
+
+  List<List<num>> _arcAt(int index) {
+    var arc = arcs[index < 0 ? ~index : index];
+
+    if (transform != null) {
+      var x = 0, y = 0;
+      arc = arc.map((quantized) {
+        final absolute = List.of(quantized);
+        absolute[0] = (x += quantized[0]) * transform.scale[0] + transform.translate[0];
+        absolute[1] = (y += quantized[1]) * transform.scale[1] + transform.translate[1];
+        return absolute;
+      }).toList();
+    }
+
+    return index < 0 ? arc.reversed.toList() : arc;
+  }
+
+  List<List<num>> _toLine(List<List<List<num>>> arcs) {
+    return arcs.fold(<List<num>>[], (prev, arc) => [...prev, ...prev.isEmpty ? arc : arc.skip(1)]);
+  }
+
+  List<List<num>> _decodeRingArcs(List<int> ringArcs) {
+    return _toLine(ringArcs.map(_arcAt).toList());
+  }
+
+  List<List<List<num>>> _decodePolygonArcs(List<List<int>> polyArcs) {
+    return polyArcs.map(_decodeRingArcs).toList();
+  }
+
+  List<List<List<List<num>>>> _decodeMultiPolygonArcs(List<List<List<int>>> multiPolyArcs) {
+    return multiPolyArcs.map(_decodePolygonArcs).toList();
+  }
+
+  // cf https://en.wikipedia.org/wiki/Even%E2%80%93odd_rule
+  bool _pointInRing(List<num> point, List<List<num>> poly) {
+    final x = point[0];
+    final y = point[1];
+    final length = poly.length;
+    var j = length - 1;
+    var c = false;
+    for (var i = 0; i < length; i++) {
+      if (((poly[i][1] > y) != (poly[j][1] > y)) && (x < poly[i][0] + (poly[j][0] - poly[i][0]) * (y - poly[i][1]) / (poly[j][1] - poly[i][1]))) {
+        c = !c;
+      }
+      j = i;
+    }
+    return c;
+  }
+
+  bool _pointInRings(List<num> point, List<List<List<num>>> rings) {
+    return rings.any((ring) => _pointInRing(point, ring));
+  }
+}
+
+class Transform {
+  final List<num> scale;
+  final List<num> translate;
+
+  Transform.parse(Map<String, dynamic> data)
+      : scale = (data['scale'] as List).cast<num>(),
+        translate = (data['translate'] as List).cast<num>();
+}
+
+abstract class Geometry extends TopologyJsonObject {
+  final dynamic id;
+  final Map<String, dynamic> properties;
+
+  Geometry.parse(Map<String, dynamic> data)
+      : id = data.containsKey('id') ? data['id'] : null,
+        properties = data.containsKey('properties') ? data['properties'] as Map<String, dynamic> : null,
+        super.parse(data);
+
+  static Geometry build(Map<String, dynamic> data) {
+    final type = _parseTopoJsonObjectType(data['type'] as String);
+    switch (type) {
+      case TopoJsonObjectType.topology:
+        return null;
+      case TopoJsonObjectType.point:
+        return Point.parse(data);
+      case TopoJsonObjectType.multipoint:
+        return MultiPoint.parse(data);
+      case TopoJsonObjectType.linestring:
+        return LineString.parse(data);
+      case TopoJsonObjectType.multilinestring:
+        return MultiLineString.parse(data);
+      case TopoJsonObjectType.polygon:
+        return Polygon.parse(data);
+      case TopoJsonObjectType.multipolygon:
+        return MultiPolygon.parse(data);
+      case TopoJsonObjectType.geometrycollection:
+        return GeometryCollection.parse(data);
+    }
+    return null;
+  }
+
+  bool containsPoint(Topology topology, List<num> point) => false;
+}
+
+class Point extends Geometry {
+  final List<num> coordinates;
+
+  Point.parse(Map<String, dynamic> data)
+      : coordinates = (data['coordinates'] as List).cast<num>(),
+        super.parse(data);
+}
+
+class MultiPoint extends Geometry {
+  final List<List<num>> coordinates;
+
+  MultiPoint.parse(Map<String, dynamic> data)
+      : coordinates = (data['coordinates'] as List).cast<List>().map((position) => position.cast<num>()).toList(),
+        super.parse(data);
+}
+
+class LineString extends Geometry {
+  final List<int> arcs;
+
+  LineString.parse(Map<String, dynamic> data)
+      : arcs = (data['arcs'] as List).cast<int>(),
+        super.parse(data);
+}
+
+class MultiLineString extends Geometry {
+  final List<List<int>> arcs;
+
+  MultiLineString.parse(Map<String, dynamic> data)
+      : arcs = (data['arcs'] as List).cast<List>().map((arc) => arc.cast<int>()).toList(),
+        super.parse(data);
+}
+
+class Polygon extends Geometry {
+  final List<List<int>> arcs;
+
+  Polygon.parse(Map<String, dynamic> data)
+      : arcs = (data['arcs'] as List).cast<List>().map((arc) => arc.cast<int>()).toList(),
+        super.parse(data);
+
+  List<List<List<num>>> _rings;
+
+  List<List<List<num>>> rings(Topology topology) {
+    _rings ??= topology._decodePolygonArcs(arcs);
+    return _rings;
+  }
+
+  @override
+  bool containsPoint(Topology topology, List<num> point) {
+    return topology._pointInRings(point, rings(topology));
+  }
+}
+
+class MultiPolygon extends Geometry {
+  final List<List<List<int>>> arcs;
+
+  MultiPolygon.parse(Map<String, dynamic> data)
+      : arcs = (data['arcs'] as List).cast<List>().map((polygon) => polygon.cast<List>().map((arc) => arc.cast<int>()).toList()).toList(),
+        super.parse(data);
+
+  List<List<List<List<num>>>> _polygons;
+
+  List<List<List<List<num>>>> polygons(Topology topology) {
+    _polygons ??= topology._decodeMultiPolygonArcs(arcs);
+    return _polygons;
+  }
+
+  @override
+  bool containsPoint(Topology topology, List<num> point) {
+    return polygons(topology).any((polygon) => topology._pointInRings(point, polygon));
+  }
+}
+
+class GeometryCollection extends Geometry {
+  final List<Geometry> geometries;
+
+  GeometryCollection.parse(Map<String, dynamic> data)
+      : geometries = (data['geometries'] as List).cast<Map<String, dynamic>>().map(Geometry.build).toList(),
+        super.parse(data);
+
+  @override
+  bool containsPoint(Topology topology, List<num> point) {
+    return geometries.any((geometry) => geometry.containsPoint(topology, point));
+  }
+}

lib/model/availability.dart

@@ -43,7 +43,7 @@ class AvesAvailability {
   }
 
   // local geolocation with `geocoder` requires Play Services
-  Future<bool> get canGeolocate => Future.wait<bool>([isConnected, hasPlayServices]).then((results) => results.every((result) => result));
+  Future<bool> get canLocatePlaces => Future.wait<bool>([isConnected, hasPlayServices]).then((results) => results.every((result) => result));
 
   Future<bool> get isNewVersionAvailable async {
     if (_isNewVersionAvailable != null) return SynchronousFuture(_isNewVersionAvailable);

lib/model/entry.dart

@@ -1,5 +1,7 @@
 import 'dart:async';
 
+import 'package:aves/geo/countries.dart';
+import 'package:aves/model/availability.dart';
 import 'package:aves/model/entry_cache.dart';
 import 'package:aves/model/favourite_repo.dart';
 import 'package:aves/model/metadata.dart';
@@ -13,6 +15,7 @@ import 'package:aves/utils/change_notifier.dart';
 import 'package:aves/utils/math_utils.dart';
 import 'package:aves/utils/time_utils.dart';
 import 'package:collection/collection.dart';
+import 'package:country_code/country_code.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:geocoder/geocoder.dart';
@@ -366,9 +369,11 @@ class AvesEntry {
     return _durationText;
   }
 
-  bool get hasGps => isCatalogued && _catalogMetadata.latitude != null;
+  bool get hasGps => _catalogMetadata?.latitude != null;
 
-  bool get isLocated => _addressDetails != null;
+  bool get hasAddress => _addressDetails != null;
+
+  bool get hasPlace => _addressDetails?.place?.isNotEmpty == true;
 
   LatLng get latLng => hasGps ? LatLng(_catalogMetadata.latitude, _catalogMetadata.longitude) : null;
 
@@ -389,7 +394,7 @@ class AvesEntry {
   String _bestTitle;
 
   String get bestTitle {
-    _bestTitle ??= (isCatalogued && _catalogMetadata.xmpTitleDescription?.isNotEmpty == true) ? _catalogMetadata.xmpTitleDescription : sourceTitle;
+    _bestTitle ??= _catalogMetadata?.xmpTitleDescription?.isNotEmpty == true ? _catalogMetadata.xmpTitleDescription : sourceTitle;
     return _bestTitle;
   }
 
@@ -444,8 +449,32 @@ class AvesEntry {
     addressChangeNotifier.notifyListeners();
   }
 
-  Future<void> locate({bool background = false}) async {
+  Future<void> locate() async {
-    if (isLocated) return;
+    await _locateCountry();
+    if (await availability.canLocatePlaces) {
+      await locatePlace(background: false);
+    }
+  }
+
+  // quick reverse geolocation to find the country, using an offline asset
+  Future<void> _locateCountry() async {
+    if (hasAddress) return;
+    final countryCode = await countryTopology.countryCode(latLng);
+    setCountry(countryCode);
+  }
+
+  void setCountry(CountryCode countryCode) {
+    if (hasPlace || countryCode == null) return;
+    addressDetails = AddressDetails(
+      contentId: contentId,
+      countryCode: countryCode.alpha2,
+      countryName: countryCode.alpha3,
+    );
+  }
+
+  // full reverse geolocation, requiring Play Services and some connectivity
+  Future<void> locatePlace({@required bool background}) async {
+    if (hasPlace) return;
 
     await catalog(background: background);
     final latitude = _catalogMetadata?.latitude;
@@ -476,8 +505,8 @@ class AvesEntry {
           locality: address.locality ?? (cc == null && cn == null && aa == null ? address.addressLine : null),
         );
       }
-    } catch (error, stackTrace) {
+    } catch (error, stack) {
-      debugPrint('$runtimeType locate failed with path=$path coordinates=$coordinates error=$error\n$stackTrace');
+      debugPrint('$runtimeType locate failed with path=$path coordinates=$coordinates error=$error\n$stack');
     }
   }
 
@@ -493,21 +522,19 @@ class AvesEntry {
         final address = addresses.first;
         return address.addressLine;
       }
-    } catch (error, stackTrace) {
+    } catch (error, stack) {
-      debugPrint('$runtimeType findAddressLine failed with path=$path coordinates=$coordinates error=$error\n$stackTrace');
+      debugPrint('$runtimeType findAddressLine failed with path=$path coordinates=$coordinates error=$error\n$stack');
     }
     return null;
   }
 
   String get shortAddress {
-    if (!isLocated) return '';
-
     // `admin area` examples: Seoul, Geneva, null
     // `locality` examples: Mapo-gu, Geneva, Annecy
     return {
-      _addressDetails.countryName,
+      _addressDetails?.countryName,
-      _addressDetails.adminArea,
+      _addressDetails?.adminArea,
-      _addressDetails.locality,
+      _addressDetails?.locality,
     }.where((part) => part != null && part.isNotEmpty).join(', ');
   }
 

lib/model/filters/location.dart

@@ -19,7 +19,7 @@ class LocationFilter extends CollectionFilter {
     if (split.length > 1) _countryCode = split[1];
 
     if (_location.isEmpty) {
-      _test = (entry) => !entry.isLocated;
+      _test = (entry) => !entry.hasGps;
     } else if (level == LocationLevel.country) {
       _test = (entry) => entry.addressDetails?.countryCode == _countryCode;
     } else if (level == LocationLevel.place) {

lib/model/metadata.dart

@@ -156,13 +156,14 @@ class OverlayMetadata {
   String toString() => '$runtimeType#${shortHash(this)}{aperture=$aperture, exposureTime=$exposureTime, focalLength=$focalLength, iso=$iso}';
 }
 
+@immutable
 class AddressDetails {
   final int contentId;
   final String countryCode, countryName, adminArea, locality;
 
   String get place => locality != null && locality.isNotEmpty ? locality : adminArea;
 
-  AddressDetails({
+  const AddressDetails({
     this.contentId,
     this.countryCode,
     this.countryName,

lib/model/metadata_db.dart

@@ -195,8 +195,8 @@ class MetadataDb {
       metadataEntries.where((metadata) => metadata != null).forEach((metadata) => _batchInsertMetadata(batch, metadata));
       await batch.commit(noResult: true);
       debugPrint('$runtimeType saveMetadata complete in ${stopwatch.elapsed.inMilliseconds}ms for ${metadataEntries.length} entries');
-    } catch (exception, stack) {
+    } catch (error, stack) {
-      debugPrint('$runtimeType failed to save metadata with exception=$exception\n$stack');
+      debugPrint('$runtimeType failed to save metadata with exception=$error\n$stack');
     }
   }
 

lib/model/settings/coordinate_format.dart

@@ -1,4 +1,4 @@
-import 'package:aves/utils/geo_utils.dart';
+import 'package:aves/geo/format.dart';
 import 'package:latlong/latlong.dart';
 
 enum CoordinateFormat { dms, decimal }

lib/model/source/location.dart

@@ -1,5 +1,6 @@
 import 'dart:math';
 
+import 'package:aves/geo/countries.dart';
 import 'package:aves/model/availability.dart';
 import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/location.dart';
@@ -28,10 +29,39 @@ mixin LocationMixin on SourceBase {
   }
 
   Future<void> locateEntries() async {
-    if (!(await availability.canGeolocate)) return;
+    await _locateCountries();
+    await _locatePlaces();
+  }
 
-//    final stopwatch = Stopwatch()..start();
+  // quick reverse geolocation to find the countries, using an offline asset
-    final byLocated = groupBy<AvesEntry, bool>(visibleEntries.where((entry) => entry.hasGps), (entry) => entry.isLocated);
+  Future<void> _locateCountries() async {
+    final todo = visibleEntries.where((entry) => entry.hasGps && entry.addressDetails?.countryCode == null).toSet();
+    if (todo.isEmpty) return;
+
+    // final stopwatch = Stopwatch()..start();
+    final countryCodeMap = await countryTopology.countryCodeMap(todo.map((entry) => entry.latLng).toSet());
+    final newAddresses = <AddressDetails>[];
+    todo.forEach((entry) {
+      final position = entry.latLng;
+      final countryCode = countryCodeMap.entries.firstWhere((kv) => kv.value.contains(position), orElse: () => null)?.key;
+      entry.setCountry(countryCode);
+      if (entry.hasAddress) {
+        newAddresses.add(entry.addressDetails);
+      }
+    });
+    if (newAddresses.isNotEmpty) {
+      await metadataDb.saveAddresses(List.unmodifiable(newAddresses));
+      onAddressMetadataChanged();
+    }
+    // debugPrint('$runtimeType _locateCountries complete in ${stopwatch.elapsed.inSeconds}s');
+  }
+
+  // full reverse geolocation, requiring Play Services and some connectivity
+  Future<void> _locatePlaces() async {
+    if (!(await availability.canLocatePlaces)) return;
+
+    // final stopwatch = Stopwatch()..start();
+    final byLocated = groupBy<AvesEntry, bool>(visibleEntries.where((entry) => entry.hasGps), (entry) => entry.hasPlace);
     final todo = byLocated[false] ?? [];
     if (todo.isEmpty) return;
 
@@ -65,12 +95,12 @@ mixin LocationMixin on SourceBase {
       if (knownLocations.containsKey(latLng)) {
         entry.addressDetails = knownLocations[latLng]?.copyWith(contentId: entry.contentId);
       } else {
-        await entry.locate(background: true);
+        await entry.locatePlace(background: true);
         // it is intended to insert `null` if the geocoder failed,
         // so that we skip geocoding of following entries with the same coordinates
         knownLocations[latLng] = entry.addressDetails;
       }
-      if (entry.isLocated) {
+      if (entry.hasPlace) {
         newAddresses.add(entry.addressDetails);
         if (newAddresses.length >= _commitCountThreshold) {
           await metadataDb.saveAddresses(List.unmodifiable(newAddresses));
@@ -80,9 +110,11 @@ mixin LocationMixin on SourceBase {
       }
       setProgress(done: ++progressDone, total: progressTotal);
     });
-    await metadataDb.saveAddresses(List.unmodifiable(newAddresses));
+    if (newAddresses.isNotEmpty) {
-    onAddressMetadataChanged();
+      await metadataDb.saveAddresses(List.unmodifiable(newAddresses));
-//    debugPrint('$runtimeType locateEntries complete in ${stopwatch.elapsed.inSeconds}s');
+      onAddressMetadataChanged();
+    }
+    // debugPrint('$runtimeType _locatePlaces complete in ${stopwatch.elapsed.inSeconds}s');
   }
 
   void onAddressMetadataChanged() {
@@ -91,7 +123,7 @@ mixin LocationMixin on SourceBase {
   }
 
   void updateLocations() {
-    final locations = visibleEntries.where((entry) => entry.isLocated).map((entry) => entry.addressDetails).toList();
+    final locations = visibleEntries.where((entry) => entry.hasAddress).map((entry) => entry.addressDetails).toList();
     sortedPlaces = List<String>.unmodifiable(locations.map((address) => address.place).where((s) => s != null && s.isNotEmpty).toSet().toList()..sort(compareAsciiUpperCase));
 
     // the same country code could be found with different country names
@@ -115,7 +147,7 @@ mixin LocationMixin on SourceBase {
       _filterEntryCountMap.clear();
       _filterRecentEntryMap.clear();
     } else {
-      final countryCodes = entries.where((entry) => entry.isLocated).map((entry) => entry.addressDetails.countryCode).toSet();
+      final countryCodes = entries.where((entry) => entry.hasPlace).map((entry) => entry.addressDetails.countryCode).toSet();
       countryCodes.forEach(_filterEntryCountMap.remove);
     }
   }

lib/services/image_file_service.dart

@@ -86,8 +86,8 @@ class ImageFileService {
             bytesReceived += chunk.length;
             try {
               onBytesReceived(bytesReceived, expectedContentLength);
-            } catch (error, stackTrace) {
+            } catch (error, stack) {
-              completer.completeError(error, stackTrace);
+              completer.completeError(error, stack);
               return;
             }
           }

lib/services/service_policy.dart

@@ -38,8 +38,8 @@ class ServicePolicy {
         () async {
           try {
             completer.complete(await platformCall());
-          } catch (error, stackTrace) {
+          } catch (error, stack) {
-            completer.completeError(error, stackTrace);
+            completer.completeError(error, stack);
           }
           _runningQueue.remove(key);
           _pickNext();

lib/services/svg_metadata_service.dart

@@ -42,8 +42,8 @@ class SvgMetadataService {
           }
         }
       }
-    } catch (exception, stack) {
+    } catch (error, stack) {
-      debugPrint('failed to parse XML from SVG with exception=$exception\n$stack');
+      debugPrint('failed to parse XML from SVG with error=$error\n$stack');
     }
     return null;
   }
@@ -78,8 +78,8 @@ class SvgMetadataService {
         if (docDir.isNotEmpty) docDirectory: docDir,
         if (metadataDir.isNotEmpty) metadataDirectory: metadataDir,
       };
-    } catch (exception, stack) {
+    } catch (error, stack) {
-      debugPrint('failed to parse XML from SVG with exception=$exception\n$stack');
+      debugPrint('failed to parse XML from SVG with error=$error\n$stack');
       return null;
     }
   }

lib/utils/change_notifier.dart

@@ -18,8 +18,8 @@ class AChangeNotifier implements Listenable {
     for (final listener in localListeners) {
       try {
         if (_listeners.contains(listener)) listener();
-      } catch (exception, stack) {
+      } catch (error, stack) {
-        debugPrint('$runtimeType failed to notify listeners with exception=$exception\n$stack');
+        debugPrint('$runtimeType failed to notify listeners with error=$error\n$stack');
       }
     }
   }

lib/utils/constants.dart

@@ -89,6 +89,12 @@ class Constants {
       licenseUrl: 'https://github.com/flutter/plugins/blob/master/packages/connectivity/connectivity/LICENSE',
       sourceUrl: 'https://github.com/flutter/plugins/blob/master/packages/connectivity/connectivity',
     ),
+    Dependency(
+      name: 'Country Code',
+      license: 'MIT',
+      licenseUrl: 'https://github.com/denixport/dart.country/blob/master/LICENSE',
+      sourceUrl: 'https://github.com/denixport/dart.country',
+    ),
     Dependency(
       name: 'Decorated Icon',
       license: 'MIT',

lib/widgets/debug/app_debug_page.dart

@@ -63,7 +63,8 @@ class _AppDebugPageState extends State<AppDebugPage> {
   Widget _buildGeneralTabView() {
     final catalogued = visibleEntries.where((entry) => entry.isCatalogued);
     final withGps = catalogued.where((entry) => entry.hasGps);
-    final located = withGps.where((entry) => entry.isLocated);
+    final withAddress = withGps.where((entry) => entry.hasAddress);
+    final withPlace = withGps.where((entry) => entry.hasPlace);
     return AvesExpansionTile(
       title: 'General',
       children: [
@@ -104,7 +105,8 @@ class _AppDebugPageState extends State<AppDebugPage> {
               'Visible entries': '${visibleEntries.length}',
               'Catalogued': '${catalogued.length}',
               'With GPS': '${withGps.length}',
-              'With address': '${located.length}',
+              'With address': '${withAddress.length}',
+              'With place': '${withPlace.length}',
             },
           ),
         ),

lib/widgets/home_page.dart

@@ -1,5 +1,4 @@
 import 'package:aves/main.dart';
-import 'package:aves/model/availability.dart';
 import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/model/settings/home_page.dart';
@@ -114,12 +113,6 @@ class _HomePageState extends State<HomePage> {
     if (entry != null) {
       // cataloguing is essential for coordinates and video rotation
       await entry.catalog();
-      // locating is fine in the background
-      unawaited(availability.canGeolocate.then((connected) {
-        if (connected) {
-          entry.locate();
-        }
-      }));
     }
     return entry;
   }

lib/widgets/stats/stats.dart

@@ -38,7 +38,7 @@ class StatsPage extends StatelessWidget {
     this.parentCollection,
   }) : assert(source != null) {
     entries.forEach((entry) {
-      if (entry.isLocated) {
+      if (entry.hasAddress) {
         final address = entry.addressDetails;
         var country = address.countryName;
         if (country != null && country.isNotEmpty) {

lib/widgets/viewer/debug_page.dart

@@ -1,7 +1,7 @@
 import 'package:aves/image_providers/uri_picture_provider.dart';
 import 'package:aves/main.dart';
-import 'package:aves/model/entry_images.dart';
 import 'package:aves/model/entry.dart';
+import 'package:aves/model/entry_images.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:aves/widgets/viewer/debug/db.dart';
 import 'package:aves/widgets/viewer/debug/metadata.dart';
@@ -106,7 +106,8 @@ class ViewerDebugPage extends StatelessWidget {
         Divider(),
         InfoRowGroup({
           'hasGps': '${entry.hasGps}',
-          'isLocated': '${entry.isLocated}',
+          'hasAddress': '${entry.hasAddress}',
+          'hasPlace': '${entry.hasPlace}',
           'latLng': '${entry.latLng}',
           'geoUri': '${entry.geoUri}',
         }),

lib/widgets/viewer/entry_vertical_pager.dart

@@ -1,6 +1,5 @@
 import 'dart:math';
 
-import 'package:aves/model/availability.dart';
 import 'package:aves/model/entry.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/widgets/common/magnifier/pan/scroll_physics.dart';
@@ -152,11 +151,7 @@ class _ViewerVerticalPageViewState extends State<ViewerVerticalPageView> {
       // make sure to locate the entry,
       // so that we can display the address instead of coordinates
       // even when initial collection locating has not reached this entry yet
-      availability.canGeolocate.then((connected) {
+      entry.locate();
-        if (connected) {
-          entry.locate();
-        }
-      });
     } else {
       Navigator.pop(context);
     }

lib/widgets/viewer/info/location_section.dart

@@ -83,7 +83,7 @@ class _LocationSectionState extends State<LocationSection> with TickerProviderSt
     if (showMap) {
       _loadedUri = entry.uri;
       final filters = <LocationFilter>[];
-      if (entry.isLocated) {
+      if (entry.hasAddress) {
         final address = entry.addressDetails;
         final country = address.countryName;
         if (country != null && country.isNotEmpty) filters.add(LocationFilter(LocationLevel.country, '$country${LocationFilter.locationSeparator}${address.countryCode}'));
@@ -181,7 +181,7 @@ class _AddressInfoGroupState extends State<_AddressInfoGroup> {
   @override
   void initState() {
     super.initState();
-    _addressLineLoader = availability.canGeolocate.then((connected) {
+    _addressLineLoader = availability.canLocatePlaces.then((connected) {
       if (connected) {
         return entry.findAddressLine();
       }

lib/widgets/viewer/overlay/bottom.dart

@@ -309,7 +309,7 @@ class _LocationRow extends AnimatedWidget {
   @override
   Widget build(BuildContext context) {
     String location;
-    if (entry.isLocated) {
+    if (entry.hasAddress) {
       location = entry.shortAddress;
     } else if (entry.hasGps) {
       location = settings.coordinateFormat.format(entry.latLng);

pubspec.lock

@@ -148,6 +148,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.1.1"
+  country_code:
+    dependency: "direct main"
+    description:
+      name: country_code
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.1.1"
   coverage:
     dependency: transitive
     description:

pubspec.yaml

@@ -34,6 +34,7 @@ dependencies:
   charts_flutter:
   collection:
   connectivity:
+  country_code:
   decorated_icon:
   event_bus:
   expansion_tile_card:

test/geo/countries_test.dart

@@ -0,0 +1,32 @@
+import 'package:aves/geo/countries.dart';
+import 'package:aves/geo/topojson.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:latlong/latlong.dart';
+
+void main() {
+  // [lng, lat, z]
+  const buenosAires = [-58.381667, -34.603333];
+  const paris = [2.348777, 48.875683];
+  const seoul = [126.99, 37.56, 42];
+  const argentinaN3String = '032';
+  const franceN3String = '250';
+  const southKoreaN3String = '410';
+
+  test('Parse countries', () async {
+    TestWidgetsFlutterBinding.ensureInitialized();
+    final topo = await countryTopology.getTopology();
+    final countries = topo.objects['countries'] as GeometryCollection;
+
+    final argentina = countries.geometries.firstWhere((geometry) => geometry.id == argentinaN3String);
+    expect(argentina.properties['name'], 'Argentina');
+    expect(argentina.containsPoint(topo, buenosAires), true);
+    expect(argentina.containsPoint(topo, seoul), false);
+  });
+
+  test('Get country id', () async {
+    TestWidgetsFlutterBinding.ensureInitialized();
+    expect(await countryTopology.numericCode(LatLng(buenosAires[1], buenosAires[0])), int.parse(argentinaN3String));
+    expect(await countryTopology.numericCode(LatLng(seoul[1], seoul[0])), int.parse(southKoreaN3String));
+    expect(await countryTopology.numericCode(LatLng(paris[1], paris[0])), int.parse(franceN3String));
+  });
+}

test/geo/format_test.dart

@@ -1,4 +1,4 @@
-import 'package:aves/utils/geo_utils.dart';
+import 'package:aves/geo/format.dart';
 import 'package:latlong/latlong.dart';
 import 'package:test/test.dart';
 

test/geo/topojson_test.dart

@@ -0,0 +1,116 @@
+import 'package:aves/geo/topojson.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  const example1 = '''
+{
+  "type": "Topology",
+  "objects": {
+    "example": {
+      "type": "GeometryCollection",
+      "geometries": [
+        {
+          "type": "Point",
+          "properties": {
+            "prop0": "value0"
+          },
+          "coordinates": [102, 0.5]
+        },
+        {
+          "type": "LineString",
+          "properties": {
+            "prop0": "value0",
+            "prop1": 0
+          },
+          "arcs": [0]
+        },
+        {
+          "type": "Polygon",
+          "properties": {
+            "prop0": "value0",
+            "prop1": {
+              "this": "that"
+            }
+          },
+          "arcs": [[-2]]
+        }
+      ]
+    }
+  },
+  "arcs": [
+    [[102, 0], [103, 1], [104, 0], [105, 1]],
+    [[100, 0], [101, 0], [101, 1], [100, 1], [100, 0]]
+  ]
+}
+''';
+
+  const example1Quantized = '''
+{
+  "type": "Topology",
+  "transform": {
+    "scale": [0.0005000500050005, 0.00010001000100010001],
+    "translate": [100, 0]
+  },
+  "objects": {
+    "example": {
+      "type": "GeometryCollection",
+      "geometries": [
+        {
+          "type": "Point",
+          "properties": {
+            "prop0": "value0"
+          },
+          "coordinates": [4000, 5000]
+        },
+        {
+          "type": "LineString",
+          "properties": {
+            "prop0": "value0",
+            "prop1": 0
+          },
+          "arcs": [0]
+        },
+        {
+          "type": "Polygon",
+          "properties": {
+            "prop0": "value0",
+            "prop1": {
+              "this": "that"
+            }
+          },
+          "arcs": [[1]]
+        }
+      ]
+    }
+  },
+  "arcs": [
+    [[4000, 0], [1999, 9999], [2000, -9999], [2000, 9999]],
+    [[0, 0], [0, 9999], [2000, 0], [0, -9999], [-2000, 0]]
+  ]
+}
+''';
+
+  test('parse example', () async {
+    final topo = await TopoJson().parse(example1);
+    expect(topo.objects.containsKey('example'), true);
+
+    final exampleObj = topo.objects['example'] as GeometryCollection;
+    expect(exampleObj.geometries.length, 3);
+
+    final point = exampleObj.geometries[0] as Point;
+    expect(point.coordinates, [102, 0.5]);
+
+    final lineString = exampleObj.geometries[1] as LineString;
+    expect(lineString.arcs, [0]);
+
+    final polygon = exampleObj.geometries[2] as Polygon;
+    expect(polygon.arcs.first, [-2]);
+    expect(polygon.properties.containsKey('prop0'), true);
+  });
+
+  test('parse quantized example', () async {
+    final topo = await TopoJson().parse(example1Quantized);
+    expect(topo.arcs.first.first, [4000, 0]);
+    expect(topo.transform.scale, [0.0005000500050005, 0.00010001000100010001]);
+  });
+}