perf: improved filtering

lib/model/entry.dart

@@ -376,7 +376,12 @@ class AvesEntry {
     return 'geo:$latitude,$longitude?q=$latitude,$longitude';
   }
 
-  List<String> get xmpSubjects => _catalogMetadata?.xmpSubjects?.split(';')?.where((tag) => tag.isNotEmpty)?.toList() ?? [];
+  List<String> _xmpSubjects;
+
+  List<String> get xmpSubjects {
+    _xmpSubjects ??= _catalogMetadata?.xmpSubjects?.split(';')?.where((tag) => tag.isNotEmpty)?.toList() ?? [];
+    return _xmpSubjects;
+  }
 
   String _bestTitle;
 
@@ -400,6 +405,7 @@ class AvesEntry {
     catalogDateMillis = newMetadata?.dateMillis;
     _catalogMetadata = newMetadata;
     _bestTitle = null;
+    _xmpSubjects = null;
     metadataChangeNotifier.notifyListeners();
 
     _onImageChanged(oldDateModifiedSecs, oldRotationDegrees, oldIsFlipped);

lib/model/filters/album.dart

@@ -1,5 +1,4 @@
 import 'package:aves/image_providers/app_icon_image_provider.dart';
-import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:aves/utils/android_file_utils.dart';
@@ -33,7 +32,7 @@ class AlbumFilter extends CollectionFilter {
       };
 
   @override
-  bool filter(AvesEntry entry) => entry.directory == album;
+  EntryFilter get filter => (entry) => entry.directory == album;
 
   @override
   String get label => uniqueName ?? album.split(separator).last;

lib/model/filters/favourite.dart

@@ -1,4 +1,3 @@
-import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:flutter/material.dart';
@@ -13,7 +12,7 @@ class FavouriteFilter extends CollectionFilter {
       };
 
   @override
-  bool filter(AvesEntry entry) => entry.isFavourite;
+  EntryFilter get filter => (entry) => entry.isFavourite;
 
   @override
   String get label => 'Favourite';

lib/model/filters/filters.dart

@@ -49,7 +49,7 @@ abstract class CollectionFilter implements Comparable<CollectionFilter> {
 
   String toJson() => jsonEncode(toMap());
 
-  bool filter(AvesEntry entry);
+  EntryFilter get filter;
 
   bool get isUnique => true;
 
@@ -91,3 +91,5 @@ class FilterGridItem<T extends CollectionFilter> {
   @override
   int get hashCode => hashValues(filter, entry);
 }
+
+typedef EntryFilter = bool Function(AvesEntry);

lib/model/filters/location.dart

@@ -1,4 +1,3 @@
-import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:flutter/foundation.dart';
@@ -12,11 +11,20 @@ class LocationFilter extends CollectionFilter {
   final LocationLevel level;
   String _location;
   String _countryCode;
+  EntryFilter _filter;
 
   LocationFilter(this.level, this._location) {
     final split = _location.split(locationSeparator);
     if (split.isNotEmpty) _location = split[0];
     if (split.length > 1) _countryCode = split[1];
+
+    if (_location.isEmpty) {
+      _filter = (entry) => !entry.isLocated;
+    } else if (level == LocationLevel.country) {
+      _filter = (entry) => entry.addressDetails?.countryCode == _countryCode;
+    } else if (level == LocationLevel.place) {
+      _filter = (entry) => entry.addressDetails?.place == _location;
+    }
   }
 
   LocationFilter.fromMap(Map<String, dynamic> json)
@@ -35,7 +43,7 @@ class LocationFilter extends CollectionFilter {
   String get countryNameAndCode => '$_location$locationSeparator$_countryCode';
 
   @override
-  bool filter(AvesEntry entry) => _location.isEmpty ? !entry.isLocated : entry.isLocated && ((level == LocationLevel.country && entry.addressDetails.countryCode == _countryCode) || (level == LocationLevel.place && entry.addressDetails.place == _location));
+  EntryFilter get filter => _filter;
 
   @override
   String get label => _location.isEmpty ? emptyLabel : _location;

lib/model/filters/mime.dart

@@ -1,5 +1,4 @@
 import 'package:aves/model/filters/filters.dart';
-import 'package:aves/model/entry.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:aves/utils/mime_utils.dart';
 import 'package:flutter/foundation.dart';
@@ -15,7 +14,7 @@ class MimeFilter extends CollectionFilter {
   static const geotiff = 'aves/geotiff'; // subset of `image/tiff`
 
   final String mime;
-  bool Function(AvesEntry) _filter;
+  EntryFilter _filter;
   String _label;
   IconData _icon;
 
@@ -67,7 +66,7 @@ class MimeFilter extends CollectionFilter {
       };
 
   @override
-  bool filter(AvesEntry entry) => _filter(entry);
+  EntryFilter get filter => _filter;
 
   @override
   String get label => _label;

lib/model/filters/query.dart

@@ -1,4 +1,3 @@
-import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:flutter/foundation.dart';
@@ -12,7 +11,7 @@ class QueryFilter extends CollectionFilter {
 
   final String query;
   final bool colorful;
-  bool Function(AvesEntry) _filter;
+  EntryFilter _filter;
 
   QueryFilter(this.query, {this.colorful = true}) {
     var upQuery = query.toUpperCase();
@@ -44,7 +43,7 @@ class QueryFilter extends CollectionFilter {
       };
 
   @override
-  bool filter(AvesEntry entry) => _filter(entry);
+  EntryFilter get filter => _filter;
 
   @override
   bool get isUnique => false;

lib/model/filters/tag.dart

@@ -1,4 +1,3 @@
-import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:flutter/foundation.dart';
@@ -9,8 +8,15 @@ class TagFilter extends CollectionFilter {
   static const emptyLabel = 'untagged';
 
   final String tag;
+  EntryFilter _filter;
 
-  const TagFilter(this.tag);
+  TagFilter(this.tag) {
+    if (tag.isEmpty) {
+      _filter = (entry) => entry.xmpSubjects.isEmpty;
+    } else {
+      _filter = (entry) => entry.xmpSubjects.contains(tag);
+    }
+  }
 
   TagFilter.fromMap(Map<String, dynamic> json)
       : this(
@@ -24,7 +30,7 @@ class TagFilter extends CollectionFilter {
       };
 
   @override
-  bool filter(AvesEntry entry) => tag.isEmpty ? entry.xmpSubjects.isEmpty : entry.xmpSubjects.contains(tag);
+  EntryFilter get filter => _filter;
 
   @override
   bool get isUnique => false;