diff --git a/analysis_options.yaml b/analysis_options.yaml
index f779f939d..157ed9498 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -3,3 +3,10 @@ include: package:pedantic/analysis_options.yaml
 analyzer:
   exclude:
     - lib/generated_plugin_registrant.dart
+
+linter:
+  rules:
+    - always_declare_return_types
+    - prefer_const_constructors
+    - prefer_const_constructors_in_immutables
+    - prefer_const_declarations
diff --git a/lib/main.dart b/lib/main.dart
index 0698d452c..b84007b9d 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -16,10 +16,10 @@ import 'package:pedantic/pedantic.dart';
 import 'package:permission_handler/permission_handler.dart';
 import 'package:screen/screen.dart';
 
-final stopwatch = Stopwatch()..start();
+final _stopwatch = Stopwatch()..start();
 
 void main() {
-  debugPrint('main start, elapsed=${stopwatch.elapsed}');
+  debugPrint('main start, elapsed=${_stopwatch.elapsed}');
   // initialize binding/plugins to configure Skia before `runApp`
   WidgetsFlutterBinding.ensureInitialized(); // 220ms
 //  debugPrint('main WidgetsFlutterBinding.ensureInitialized done, elapsed=${stopwatch.elapsed}');
@@ -61,7 +61,7 @@ class HomePage extends StatefulWidget {
 class _HomePageState extends State<HomePage> {
   static const EventChannel eventChannel = EventChannel('deckers.thibault/aves/mediastore');
 
-  ImageCollection localMediaCollection = ImageCollection(entries: List());
+  ImageCollection localMediaCollection = ImageCollection(entries: []);
 
   @override
   void initState() {
@@ -72,7 +72,7 @@ class _HomePageState extends State<HomePage> {
   }
 
   Future<void> setup() async {
-    debugPrint('$runtimeType setup start, elapsed=${stopwatch.elapsed}');
+    debugPrint('$runtimeType setup start, elapsed=${_stopwatch.elapsed}');
     // TODO reduce permission check time
     final permissions = await PermissionHandler().requestPermissions([
       PermissionGroup.storage
@@ -91,7 +91,7 @@ class _HomePageState extends State<HomePage> {
     await settings.init(); // <20ms
     localMediaCollection.groupFactor = settings.collectionGroupFactor;
     localMediaCollection.sortFactor = settings.collectionSortFactor;
-    debugPrint('$runtimeType setup settings.init done, elapsed=${stopwatch.elapsed}');
+    debugPrint('$runtimeType setup settings.init done, elapsed=${_stopwatch.elapsed}');
 
     await metadataDb.init(); // <20ms
     final currentTimeZone = await FlutterNativeTimezone.getLocalTimezone(); // <20ms
@@ -107,7 +107,7 @@ class _HomePageState extends State<HomePage> {
     eventChannel.receiveBroadcastStream().cast<Map>().listen(
           (entryMap) => localMediaCollection.add(ImageEntry.fromMap(entryMap)),
           onDone: () async {
-            debugPrint('$runtimeType mediastore stream done, elapsed=${stopwatch.elapsed}');
+            debugPrint('$runtimeType mediastore stream done, elapsed=${_stopwatch.elapsed}');
             localMediaCollection.updateSections(); // <50ms
             // TODO reduce setup time until here
             localMediaCollection.updateAlbums(); // <50ms
@@ -115,7 +115,7 @@ class _HomePageState extends State<HomePage> {
             await localMediaCollection.catalogEntries(); // <50ms
             await localMediaCollection.loadAddresses(); // 350ms
             await localMediaCollection.locateEntries(); // <50ms
-            debugPrint('$runtimeType setup end, elapsed=${stopwatch.elapsed}');
+            debugPrint('$runtimeType setup end, elapsed=${_stopwatch.elapsed}');
           },
           onError: (error) => debugPrint('$runtimeType mediastore stream error=$error'),
         );
diff --git a/lib/model/image_collection.dart b/lib/model/image_collection.dart
index 37dcc183c..7184782e9 100644
--- a/lib/model/image_collection.dart
+++ b/lib/model/image_collection.dart
@@ -8,11 +8,11 @@ import 'package:path/path.dart';
 
 class ImageCollection with ChangeNotifier {
   final List<ImageEntry> _rawEntries;
-  Map<dynamic, List<ImageEntry>> sections = Map();
+  Map<dynamic, List<ImageEntry>> sections = {};
   GroupFactor groupFactor = GroupFactor.month;
   SortFactor sortFactor = SortFactor.date;
-  List<String> sortedAlbums = List.unmodifiable(Iterable.empty());
-  List<String> sortedTags = List.unmodifiable(Iterable.empty());
+  List<String> sortedAlbums = List.unmodifiable(const Iterable.empty());
+  List<String> sortedTags = List.unmodifiable(const Iterable.empty());
 
   ImageCollection({
     @required List<ImageEntry> entries,
@@ -140,7 +140,7 @@ class ImageCollection with ChangeNotifier {
   Future<void> catalogEntries() async {
     final start = DateTime.now();
     final uncataloguedEntries = _rawEntries.where((entry) => !entry.isCatalogued).toList();
-    final newMetadata = List<CatalogMetadata>();
+    final newMetadata = <CatalogMetadata>[];
     await Future.forEach<ImageEntry>(uncataloguedEntries, (entry) async {
       await entry.catalog();
       newMetadata.add(entry.catalogMetadata);
@@ -153,7 +153,7 @@ class ImageCollection with ChangeNotifier {
   Future<void> locateEntries() async {
     final start = DateTime.now();
     final unlocatedEntries = _rawEntries.where((entry) => entry.hasGps && !entry.isLocated).toList();
-    final newAddresses = List<AddressDetails>();
+    final newAddresses = <AddressDetails>[];
     await Future.forEach<ImageEntry>(unlocatedEntries, (entry) async {
       await entry.locate();
       newAddresses.add(entry.addressDetails);
diff --git a/lib/model/image_entry.dart b/lib/model/image_entry.dart
index 55f4e1317..db7caab4f 100644
--- a/lib/model/image_entry.dart
+++ b/lib/model/image_entry.dart
@@ -1,5 +1,3 @@
-import 'dart:collection';
-
 import 'package:aves/model/image_file_service.dart';
 import 'package:aves/model/image_metadata.dart';
 import 'package:aves/model/metadata_service.dart';
@@ -50,19 +48,19 @@ class ImageEntry {
 
   factory ImageEntry.fromMap(Map map) {
     return ImageEntry(
-      uri: map['uri'],
-      path: map['path'],
-      contentId: map['contentId'],
-      mimeType: map['mimeType'],
-      width: map['width'],
-      height: map['height'],
-      orientationDegrees: map['orientationDegrees'],
-      sizeBytes: map['sizeBytes'],
-      title: map['title'],
-      dateModifiedSecs: map['dateModifiedSecs'],
-      sourceDateTakenMillis: map['sourceDateTakenMillis'],
-      bucketDisplayName: map['bucketDisplayName'],
-      durationMillis: map['durationMillis'],
+      uri: map['uri'] as String,
+      path: map['path'] as String,
+      contentId: map['contentId'] as int,
+      mimeType: map['mimeType'] as String,
+      width: map['width'] as int,
+      height: map['height'] as int,
+      orientationDegrees: map['orientationDegrees'] as int,
+      sizeBytes: map['sizeBytes'] as int,
+      title: map['title'] as String,
+      dateModifiedSecs: map['dateModifiedSecs'] as int,
+      sourceDateTakenMillis: map['sourceDateTakenMillis'] as int,
+      bucketDisplayName: map['bucketDisplayName'] as String,
+      durationMillis: map['durationMillis'] as int,
     );
   }
 
@@ -180,13 +178,11 @@ class ImageEntry {
 
     // admin area examples: Seoul, Geneva, null
     // locality examples: Mapo-gu, Geneva, Annecy
-    return LinkedHashSet.of(
-      [
-        addressDetails.countryName,
-        addressDetails.adminArea,
-        addressDetails.locality
-      ],
-    ).where((part) => part != null && part.isNotEmpty).join(', ');
+    return {
+      addressDetails.countryName,
+      addressDetails.adminArea,
+      addressDetails.locality
+    }.where((part) => part != null && part.isNotEmpty).join(', ');
   }
 
   bool search(String query) {
@@ -203,13 +199,13 @@ class ImageEntry {
     if (newFields.isEmpty) return false;
 
     final uri = newFields['uri'];
-    if (uri != null) this.uri = uri;
+    if (uri is String) this.uri = uri;
     final path = newFields['path'];
-    if (path != null) this.path = path;
+    if (path is String) this.path = path;
     final contentId = newFields['contentId'];
-    if (contentId != null) this.contentId = contentId;
+    if (contentId is int) this.contentId = contentId;
     final title = newFields['title'];
-    if (title != null) this.title = title;
+    if (title is String) this.title = title;
     metadataChangeNotifier.notifyListeners();
     return true;
   }
@@ -223,11 +219,11 @@ class ImageEntry {
     if (newFields.isEmpty) return false;
 
     final width = newFields['width'];
-    if (width != null) this.width = width;
+    if (width is int) this.width = width;
     final height = newFields['height'];
-    if (height != null) this.height = height;
+    if (height is int) this.height = height;
     final orientationDegrees = newFields['orientationDegrees'];
-    if (orientationDegrees != null) this.orientationDegrees = orientationDegrees;
+    if (orientationDegrees is int) this.orientationDegrees = orientationDegrees;
     imageChangeNotifier.notifyListeners();
     return true;
   }
diff --git a/lib/model/image_file_service.dart b/lib/model/image_file_service.dart
index 1da519c21..e19491e90 100644
--- a/lib/model/image_file_service.dart
+++ b/lib/model/image_file_service.dart
@@ -65,7 +65,7 @@ class ImageFileService {
     } on PlatformException catch (e) {
       debugPrint('rename failed with exception=${e.message}');
     }
-    return Map();
+    return {};
   }
 
   static Future<Map> rotate(ImageEntry entry, {@required bool clockwise}) async {
@@ -79,6 +79,6 @@ class ImageFileService {
     } on PlatformException catch (e) {
       debugPrint('rotate failed with exception=${e.message}');
     }
-    return Map();
+    return {};
   }
 }
diff --git a/lib/model/metadata_db.dart b/lib/model/metadata_db.dart
index 0ad5a037a..db91f6471 100644
--- a/lib/model/metadata_db.dart
+++ b/lib/model/metadata_db.dart
@@ -10,8 +10,8 @@ class MetadataDb {
 
   Future<String> get path async => join(await getDatabasesPath(), 'metadata.db');
 
-  static final metadataTable = 'metadata';
-  static final addressTable = 'address';
+  static const metadataTable = 'metadata';
+  static const addressTable = 'address';
 
   MetadataDb._private();
 
diff --git a/lib/model/metadata_service.dart b/lib/model/metadata_service.dart
index 883002049..0c5ffe779 100644
--- a/lib/model/metadata_service.dart
+++ b/lib/model/metadata_service.dart
@@ -17,7 +17,7 @@ class MetadataService {
     } on PlatformException catch (e) {
       debugPrint('getAllMetadata failed with exception=${e.message}');
     }
-    return Map();
+    return {};
   }
 
   static Future<CatalogMetadata> getCatalogMetadata(ImageEntry entry) async {
diff --git a/lib/model/settings.dart b/lib/model/settings.dart
index 16e9f2c06..b52de626d 100644
--- a/lib/model/settings.dart
+++ b/lib/model/settings.dart
@@ -5,12 +5,12 @@ import 'package:shared_preferences/shared_preferences.dart';
 
 final Settings settings = Settings._private();
 
-typedef void SettingsCallback(String key, dynamic oldValue, dynamic newValue);
+typedef SettingsCallback = void Function(String key, dynamic oldValue, dynamic newValue);
 
 class Settings {
   static SharedPreferences prefs;
 
-  ObserverList<SettingsCallback> _listeners = ObserverList<SettingsCallback>();
+  final ObserverList<SettingsCallback> _listeners = ObserverList<SettingsCallback>();
 
   Settings._private();
 
@@ -32,7 +32,7 @@ class Settings {
     debugPrint('$runtimeType notifyListeners key=$key, old=$oldValue, new=$newValue');
     if (_listeners != null) {
       final List<SettingsCallback> localListeners = _listeners.toList();
-      for (SettingsCallback listener in localListeners) {
+      for (final listener in localListeners) {
         try {
           if (_listeners.contains(listener)) {
             listener(key, oldValue, newValue);
@@ -66,7 +66,7 @@ class Settings {
 
   T getEnumOrDefault<T>(String key, T defaultValue, Iterable<T> values) {
     final valueString = prefs.getString(key);
-    for (T element in values) {
+    for (final element in values) {
       if (element.toString() == valueString) {
         return element;
       }
diff --git a/lib/utils/android_app_service.dart b/lib/utils/android_app_service.dart
index 208a067b8..06fb8482a 100644
--- a/lib/utils/android_app_service.dart
+++ b/lib/utils/android_app_service.dart
@@ -13,7 +13,7 @@ class AndroidAppService {
     } on PlatformException catch (e) {
       debugPrint('getAppNames failed with exception=${e.message}');
     }
-    return Map();
+    return {};
   }
 
   static Future<Uint8List> getAppIcon(String packageName, int size) async {
diff --git a/lib/utils/geo_utils.dart b/lib/utils/geo_utils.dart
index fa24c3bab..506c1b29f 100644
--- a/lib/utils/geo_utils.dart
+++ b/lib/utils/geo_utils.dart
@@ -27,7 +27,7 @@ String _decimal2sexagesimal(final double dec) {
   final List<int> minParts = _split(min);
   final int minFractionalPart = minParts[1];
 
-  final double sec = (double.parse('0.$minFractionalPart') * 60);
+  final double sec = double.parse('0.$minFractionalPart') * 60;
 
   return '$deg° ${min.floor()}′ ${_round(sec, decimals: 2).toStringAsFixed(2)}″';
 }
diff --git a/lib/utils/time_utils.dart b/lib/utils/time_utils.dart
index a1f58e669..7ca2dd036 100644
--- a/lib/utils/time_utils.dart
+++ b/lib/utils/time_utils.dart
@@ -6,7 +6,7 @@ bool isAtSameDayAs(DateTime d1, DateTime d2) => isAtSameMonthAs(d1, d2) && d1.da
 
 bool isToday(DateTime d) => isAtSameDayAs(d, DateTime.now());
 
-bool isYesterday(DateTime d) => isAtSameDayAs(d, DateTime.now().subtract(Duration(days: 1)));
+bool isYesterday(DateTime d) => isAtSameDayAs(d, DateTime.now().subtract(const Duration(days: 1)));
 
 bool isThisMonth(DateTime d) => isAtSameMonthAs(d, DateTime.now());
 
diff --git a/lib/widgets/album/all_collection_drawer.dart b/lib/widgets/album/all_collection_drawer.dart
index 6dc52a838..af595b897 100644
--- a/lib/widgets/album/all_collection_drawer.dart
+++ b/lib/widgets/album/all_collection_drawer.dart
@@ -21,6 +21,9 @@ class AllCollectionDrawer extends StatelessWidget {
         padding: EdgeInsets.only(bottom: window.viewInsets.bottom),
         children: [
           DrawerHeader(
+            decoration: BoxDecoration(
+              color: Theme.of(context).accentColor,
+            ),
             child: SafeArea(
               child: Column(
                 crossAxisAlignment: CrossAxisAlignment.start,
@@ -28,18 +31,18 @@ class AllCollectionDrawer extends StatelessWidget {
                   Row(
                     children: [
                       CircleAvatar(
+                        backgroundColor: Colors.white,
+                        radius: 44,
                         child: Padding(
-                          padding: EdgeInsets.only(top: 6.0),
+                          padding: const EdgeInsets.only(top: 6.0),
                           child: SvgPicture.asset(
                             'assets/aves_logo.svg',
                             width: 64,
                           ),
                         ),
-                        backgroundColor: Colors.white,
-                        radius: 44,
                       ),
-                      SizedBox(width: 16),
-                      Text(
+                      const SizedBox(width: 16),
+                      const Text(
                         'Aves',
                         style: TextStyle(
                           fontSize: 44,
@@ -48,28 +51,28 @@ class AllCollectionDrawer extends StatelessWidget {
                       ),
                     ],
                   ),
-                  SizedBox(height: 16),
+                  const SizedBox(height: 16),
                   Row(
                     mainAxisAlignment: MainAxisAlignment.spaceBetween,
                     children: [
                       Row(children: [
                         Icon(Icons.photo_library),
-                        SizedBox(width: 4),
+                        const SizedBox(width: 4),
                         Text('${collection.imageCount}')
                       ]),
                       Row(children: [
                         Icon(Icons.video_library),
-                        SizedBox(width: 4),
+                        const SizedBox(width: 4),
                         Text('${collection.videoCount}')
                       ]),
                       Row(children: [
                         Icon(Icons.photo_album),
-                        SizedBox(width: 4),
+                        const SizedBox(width: 4),
                         Text('${collection.albumCount}')
                       ]),
                       Row(children: [
                         Icon(Icons.label),
-                        SizedBox(width: 4),
+                        const SizedBox(width: 4),
                         Text('${collection.tagCount}')
                       ]),
                     ],
@@ -77,9 +80,6 @@ class AllCollectionDrawer extends StatelessWidget {
                 ],
               ),
             ),
-            decoration: BoxDecoration(
-              color: Theme.of(context).accentColor,
-            ),
           ),
           _buildFilteredCollectionNavTile(
             context: context,
@@ -87,14 +87,14 @@ class AllCollectionDrawer extends StatelessWidget {
             title: 'Videos',
             filter: (entry) => entry.isVideo,
           ),
-          Divider(),
+          const Divider(),
           ...albums.map((album) => _buildFilteredCollectionNavTile(
                 context: context,
                 leading: IconUtils.getAlbumIcon(context, album) ?? Icon(Icons.photo_album),
                 title: collection.getUniqueAlbumName(album, albums),
                 filter: (entry) => entry.directory == album,
               )),
-          Divider(),
+          const Divider(),
           ...tags.map((tag) => _buildFilteredCollectionNavTile(
                 context: context,
                 leading: Icon(Icons.label),
@@ -106,7 +106,7 @@ class AllCollectionDrawer extends StatelessWidget {
     );
   }
 
-  _buildFilteredCollectionNavTile({BuildContext context, Widget leading, String title, bool Function(ImageEntry) filter}) {
+  Widget _buildFilteredCollectionNavTile({BuildContext context, Widget leading, String title, bool Function(ImageEntry) filter}) {
     return SafeArea(
       top: false,
       bottom: false,
diff --git a/lib/widgets/album/all_collection_page.dart b/lib/widgets/album/all_collection_page.dart
index 56f7e5ce3..3c034a343 100644
--- a/lib/widgets/album/all_collection_page.dart
+++ b/lib/widgets/album/all_collection_page.dart
@@ -16,7 +16,7 @@ class AllCollectionPage extends StatelessWidget {
     return ThumbnailCollection(
       collection: collection,
       appBar: SliverAppBar(
-        title: Text('All'),
+        title: const Text('All'),
         actions: [
           IconButton(
             icon: Icon(Icons.search),
@@ -35,7 +35,7 @@ class AllCollectionPage extends StatelessWidget {
                 value: AlbumAction.sortBySize,
                 child: MenuRow(text: 'Sort by size', checked: collection.sortFactor == SortFactor.size),
               ),
-              PopupMenuDivider(),
+              const PopupMenuDivider(),
               if (collection.sortFactor == SortFactor.date) ...[
                 PopupMenuItem(
                   value: AlbumAction.groupByAlbum,
@@ -49,14 +49,14 @@ class AllCollectionPage extends StatelessWidget {
                   value: AlbumAction.groupByDay,
                   child: MenuRow(text: 'Group by day', checked: collection.groupFactor == GroupFactor.day),
                 ),
-                PopupMenuDivider(),
+                const PopupMenuDivider(),
               ],
               PopupMenuItem(
                 value: AlbumAction.debug,
                 child: MenuRow(text: 'Debug', icon: Icons.whatshot),
               ),
             ],
-            onSelected: (action) => onActionSelected(context, action),
+            onSelected: (action) => _onActionSelected(context, action),
           ),
         ],
         floating: true,
@@ -64,7 +64,7 @@ class AllCollectionPage extends StatelessWidget {
     );
   }
 
-  onActionSelected(BuildContext context, AlbumAction action) {
+  void _onActionSelected(BuildContext context, AlbumAction action) {
     switch (action) {
       case AlbumAction.debug:
         goToDebug(context);
diff --git a/lib/widgets/album/search_delegate.dart b/lib/widgets/album/search_delegate.dart
index d13dc1a9f..adf4e6d1d 100644
--- a/lib/widgets/album/search_delegate.dart
+++ b/lib/widgets/album/search_delegate.dart
@@ -43,14 +43,14 @@ class ImageSearchDelegate extends SearchDelegate<ImageEntry> {
 
   @override
   Widget buildSuggestions(BuildContext context) {
-    return SizedBox.shrink();
+    return const SizedBox.shrink();
   }
 
   @override
   Widget buildResults(BuildContext context) {
     if (query.isEmpty) {
       showSuggestions(context);
-      return SizedBox.shrink();
+      return const SizedBox.shrink();
     }
     final lowerQuery = query.toLowerCase();
     final matches = collection.sortedEntries.where((entry) => entry.search(lowerQuery)).toList();
diff --git a/lib/widgets/album/sections.dart b/lib/widgets/album/sections.dart
index fad86a943..e09cd5e32 100644
--- a/lib/widgets/album/sections.dart
+++ b/lib/widgets/album/sections.dart
@@ -7,13 +7,13 @@ class DaySectionHeader extends StatelessWidget {
   final String text;
 
   DaySectionHeader({Key key, DateTime date})
-      : text = formatDate(date),
+      : text = _formatDate(date),
         super(key: key);
 
   static DateFormat md = DateFormat.MMMMd();
   static DateFormat ymd = DateFormat.yMMMMd();
 
-  static formatDate(DateTime date) {
+  static String _formatDate(DateTime date) {
     if (isToday(date)) return 'Today';
     if (isYesterday(date)) return 'Yesterday';
     if (isThisYear(date)) return md.format(date);
@@ -30,13 +30,13 @@ class MonthSectionHeader extends StatelessWidget {
   final String text;
 
   MonthSectionHeader({Key key, DateTime date})
-      : text = formatDate(date),
+      : text = _formatDate(date),
         super(key: key);
 
   static DateFormat m = DateFormat.MMMM();
   static DateFormat ym = DateFormat.yMMMM();
 
-  static formatDate(DateTime date) {
+  static String _formatDate(DateTime date) {
     if (isThisMonth(date)) return 'This month';
     if (isThisYear(date)) return m.format(date);
     return ym.format(date);
@@ -64,7 +64,7 @@ class TitleSectionHeader extends StatelessWidget {
         fontFamily: 'Concourse Caps',
         shadows: [
           Shadow(
-            offset: Offset(0, 2),
+            offset: const Offset(0, 2),
             blurRadius: 3,
             color: Colors.grey[900],
           ),
@@ -74,12 +74,12 @@ class TitleSectionHeader extends StatelessWidget {
       outlineWidth: 2,
     );
     return Container(
-      padding: EdgeInsets.all(16),
+      padding: const EdgeInsets.all(16),
       child: leading != null
           ? Row(
               children: [
                 leading,
-                SizedBox(width: 8),
+                const SizedBox(width: 8),
                 text,
               ],
             )
diff --git a/lib/widgets/album/thumbnail_collection.dart b/lib/widgets/album/thumbnail_collection.dart
index 9e95eb82d..af4f25fed 100644
--- a/lib/widgets/album/thumbnail_collection.dart
+++ b/lib/widgets/album/thumbnail_collection.dart
@@ -13,7 +13,7 @@ class ThumbnailCollection extends AnimatedWidget {
   final ImageCollection collection;
   final Widget appBar;
 
-  ThumbnailCollection({
+  const ThumbnailCollection({
     Key key,
     this.collection,
     this.appBar,
@@ -65,6 +65,12 @@ class ThumbnailCollectionContent extends StatelessWidget {
       child: Selector<MediaQueryData, double>(
         selector: (c, mq) => mq.viewInsets.bottom,
         builder: (c, mqViewInsetsBottom, child) => DraggableScrollbar.arrows(
+          controller: _scrollController,
+          padding: EdgeInsets.only(
+            // top padding to adjust scroll thumb
+            top: topPadding,
+            bottom: mqViewInsetsBottom,
+          ),
           child: CustomScrollView(
             controller: _scrollController,
             slivers: [
@@ -89,12 +95,6 @@ class ThumbnailCollectionContent extends StatelessWidget {
               }),
             ],
           ),
-          controller: _scrollController,
-          padding: EdgeInsets.only(
-            // top padding to adjust scroll thumb
-            top: topPadding,
-            bottom: mqViewInsetsBottom,
-          ),
         ),
       ),
     );
@@ -117,7 +117,7 @@ class SectionSliver extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final columnCount = 4;
+    const columnCount = 4;
     return SliverStickyHeader(
       header: SectionHeader(
         collection: collection,
@@ -143,7 +143,7 @@ class SectionSliver extends StatelessWidget {
           addAutomaticKeepAlives: false,
           addRepaintBoundaries: true,
         ),
-        gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
+        gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
           crossAxisCount: columnCount,
         ),
       ),
@@ -151,7 +151,7 @@ class SectionSliver extends StatelessWidget {
     );
   }
 
-  _showFullscreen(BuildContext context, ImageEntry entry) {
+  void _showFullscreen(BuildContext context, ImageEntry entry) {
     Navigator.push(
       context,
       MaterialPageRoute(
@@ -178,11 +178,11 @@ class SectionHeader extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    Widget header = SizedBox.shrink();
+    Widget header = const SizedBox.shrink();
     if (collection.sortFactor == SortFactor.date) {
       switch (collection.groupFactor) {
         case GroupFactor.album:
-          Widget albumIcon = IconUtils.getAlbumIcon(context, sectionKey);
+          Widget albumIcon = IconUtils.getAlbumIcon(context, sectionKey as String);
           if (albumIcon != null) {
             albumIcon = Material(
               type: MaterialType.circle,
@@ -194,14 +194,14 @@ class SectionHeader extends StatelessWidget {
           }
           header = TitleSectionHeader(
             leading: albumIcon,
-            title: collection.getUniqueAlbumName(sectionKey, sections.keys.cast<String>()),
+            title: collection.getUniqueAlbumName(sectionKey as String, sections.keys.cast<String>()),
           );
           break;
         case GroupFactor.month:
-          header = MonthSectionHeader(date: sectionKey);
+          header = MonthSectionHeader(date: sectionKey as DateTime);
           break;
         case GroupFactor.day:
-          header = DaySectionHeader(date: sectionKey);
+          header = DaySectionHeader(date: sectionKey as DateTime);
           break;
       }
     }
diff --git a/lib/widgets/common/app_icon.dart b/lib/widgets/common/app_icon.dart
index 014a14be1..bfaf53e30 100644
--- a/lib/widgets/common/app_icon.dart
+++ b/lib/widgets/common/app_icon.dart
@@ -42,7 +42,7 @@ class AppIconState extends State<AppIcon> {
                 width: widget.size,
                 height: widget.size,
               )
-            : SizedBox.shrink();
+            : const SizedBox.shrink();
       },
     );
   }
diff --git a/lib/widgets/common/fake_app_bar.dart b/lib/widgets/common/fake_app_bar.dart
index ccbfece96..1a0308b2c 100644
--- a/lib/widgets/common/fake_app_bar.dart
+++ b/lib/widgets/common/fake_app_bar.dart
@@ -3,7 +3,7 @@ import 'package:flutter/widgets.dart';
 class FakeAppBar extends StatelessWidget with PreferredSizeWidget {
   @override
   Widget build(BuildContext context) {
-    return SafeArea(child: SizedBox.shrink());
+    return const SafeArea(child: SizedBox.shrink());
   }
 
   @override
diff --git a/lib/widgets/common/icons.dart b/lib/widgets/common/icons.dart
index 80a960e1e..9a3ab7daa 100644
--- a/lib/widgets/common/icons.dart
+++ b/lib/widgets/common/icons.dart
@@ -61,10 +61,10 @@ class OverlayIcon extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Container(
-      margin: EdgeInsets.all(1),
+      margin: const EdgeInsets.all(1),
       padding: text != null ? EdgeInsets.only(right: iconSize / 4) : null,
       decoration: BoxDecoration(
-        color: Color(0xBB000000),
+        color: const Color(0xBB000000),
         borderRadius: BorderRadius.all(
           Radius.circular(iconSize),
         ),
@@ -78,7 +78,7 @@ class OverlayIcon extends StatelessWidget {
             size: iconSize,
           ),
           if (text != null) ...[
-            SizedBox(width: 2),
+            const SizedBox(width: 2),
             Text(text),
           ]
         ],
diff --git a/lib/widgets/common/image_preview.dart b/lib/widgets/common/image_preview.dart
index 7ce43a46a..52fb9f44e 100644
--- a/lib/widgets/common/image_preview.dart
+++ b/lib/widgets/common/image_preview.dart
@@ -40,33 +40,33 @@ class ImagePreviewState extends State<ImagePreview> with AfterInitMixin {
       entry.imageChangeNotifier,
       entry.metadataChangeNotifier
     ]);
-    _entryChangeNotifier.addListener(onEntryChange);
+    _entryChangeNotifier.addListener(_onEntryChange);
   }
 
   @override
   void didInitState() {
     _devicePixelRatio = Provider.of<MediaQueryData>(context, listen: false).devicePixelRatio;
-    initByteLoader();
+    _initByteLoader();
   }
 
   @override
   void didUpdateWidget(ImagePreview old) {
     super.didUpdateWidget(old);
     if (widget.width == old.width && widget.height == old.height && uri == old.entry.uri && widget.entry.width == old.entry.width && widget.entry.height == old.entry.height && widget.entry.orientationDegrees == old.entry.orientationDegrees) return;
-    initByteLoader();
+    _initByteLoader();
   }
 
-  initByteLoader() {
+  void _initByteLoader() {
     final width = (widget.width * _devicePixelRatio).round();
     final height = (widget.height * _devicePixelRatio).round();
     _byteLoader = ImageFileService.getImageBytes(widget.entry, width, height);
   }
 
-  onEntryChange() => setState(() => initByteLoader());
+  void _onEntryChange() => setState(() => _initByteLoader());
 
   @override
   void dispose() {
-    _entryChangeNotifier.removeListener(onEntryChange);
+    _entryChangeNotifier.removeListener(_onEntryChange);
     super.dispose();
   }
 
diff --git a/lib/widgets/common/menu_row.dart b/lib/widgets/common/menu_row.dart
index 6c52b900e..26091d197 100644
--- a/lib/widgets/common/menu_row.dart
+++ b/lib/widgets/common/menu_row.dart
@@ -21,11 +21,11 @@ class MenuRow extends StatelessWidget {
             opacity: checked ? 1 : 0,
             child: Icon(Icons.done),
           ),
-          SizedBox(width: 8),
+          const SizedBox(width: 8),
         ],
         if (icon != null) ...[
           Icon(icon),
-          SizedBox(width: 8),
+          const SizedBox(width: 8),
         ],
         Text(text),
       ],
diff --git a/lib/widgets/debug_page.dart b/lib/widgets/debug_page.dart
index 780b12a05..e9459c574 100644
--- a/lib/widgets/debug_page.dart
+++ b/lib/widgets/debug_page.dart
@@ -39,48 +39,48 @@ class DebugPageState extends State<DebugPage> {
     return MediaQueryDataProvider(
       child: Scaffold(
         appBar: AppBar(
-          title: Text('Info'),
+          title: const Text('Info'),
         ),
         body: Column(
           crossAxisAlignment: CrossAxisAlignment.start,
           children: [
-            Text('Paths'),
+            const Text('Paths'),
             Text('DCIM path: ${androidFileUtils.dcimPath}'),
             Text('pictures path: ${androidFileUtils.picturesPath}'),
-            Divider(),
-            Text('Settings'),
+            const Divider(),
+            const Text('Settings'),
             Text('collectionGroupFactor: ${settings.collectionGroupFactor}'),
             Text('collectionSortFactor: ${settings.collectionSortFactor}'),
             Text('infoMapZoom: ${settings.infoMapZoom}'),
-            Divider(),
+            const Divider(),
             Text('Entries: ${entries.length}'),
             ...byMimeTypes.keys.map((mimeType) => Text('- $mimeType: ${byMimeTypes[mimeType].length}')),
             Text('Catalogued: ${catalogued.length}'),
             Text('With GPS: ${withGps.length}'),
             Text('With address: ${located.length}'),
-            Divider(),
+            const Divider(),
             RaisedButton(
               onPressed: () => metadataDb.reset(),
-              child: Text('Reset DB'),
+              child: const Text('Reset DB'),
             ),
             FutureBuilder(
               future: _dbMetadataLoader,
               builder: (futureContext, AsyncSnapshot<List<CatalogMetadata>> snapshot) {
-                if (snapshot.hasError) return Text(snapshot.error);
-                if (snapshot.connectionState != ConnectionState.done) return SizedBox.shrink();
+                if (snapshot.hasError) return Text(snapshot.error.toString());
+                if (snapshot.connectionState != ConnectionState.done) return const SizedBox.shrink();
                 return Text('DB metadata rows: ${snapshot.data.length}');
               },
             ),
             FutureBuilder(
               future: _dbAddressLoader,
               builder: (futureContext, AsyncSnapshot<List<AddressDetails>> snapshot) {
-                if (snapshot.hasError) return Text(snapshot.error);
-                if (snapshot.connectionState != ConnectionState.done) return SizedBox.shrink();
+                if (snapshot.hasError) return Text(snapshot.error.toString());
+                if (snapshot.connectionState != ConnectionState.done) return const SizedBox.shrink();
                 return Text('DB address rows: ${snapshot.data.length}');
               },
             ),
-            Divider(),
-            Text('Time dilation'),
+            const Divider(),
+            const Text('Time dilation'),
             Slider(
               value: timeDilation,
               onChanged: (v) => setState(() => timeDilation = v),
diff --git a/lib/widgets/fullscreen/fullscreen_action_delegate.dart b/lib/widgets/fullscreen/fullscreen_action_delegate.dart
index e0d9735b1..916696a9b 100644
--- a/lib/widgets/fullscreen/fullscreen_action_delegate.dart
+++ b/lib/widgets/fullscreen/fullscreen_action_delegate.dart
@@ -61,14 +61,14 @@ class FullscreenActionDelegate {
   void _showFeedback(BuildContext context, String message) {
     Flushbar(
       message: message,
-      margin: EdgeInsets.all(8),
+      margin: const EdgeInsets.all(8),
       borderRadius: 8,
       borderColor: Colors.white30,
       borderWidth: 0.5,
-      duration: Duration(seconds: 2),
+      duration: const Duration(seconds: 2),
       flushbarPosition: FlushbarPosition.TOP,
-      animationDuration: Duration(milliseconds: 600),
-    )..show(context);
+      animationDuration: const Duration(milliseconds: 600),
+    ).show(context);
   }
 
   Future<void> _print(ImageEntry entry) async {
@@ -94,15 +94,15 @@ class FullscreenActionDelegate {
       context: context,
       builder: (BuildContext context) {
         return AlertDialog(
-          content: Text('Are you sure?'),
+          content: const Text('Are you sure?'),
           actions: [
             FlatButton(
               onPressed: () => Navigator.pop(context),
-              child: Text('CANCEL'),
+              child: const Text('CANCEL'),
             ),
             FlatButton(
               onPressed: () => Navigator.pop(context, true),
-              child: Text('DELETE'),
+              child: const Text('DELETE'),
             ),
           ],
         );
@@ -130,11 +130,11 @@ class FullscreenActionDelegate {
             actions: [
               FlatButton(
                 onPressed: () => Navigator.pop(context),
-                child: Text('CANCEL'),
+                child: const Text('CANCEL'),
               ),
               FlatButton(
                 onPressed: () => Navigator.pop(context, controller.text),
-                child: Text('APPLY'),
+                child: const Text('APPLY'),
               ),
             ],
           );
diff --git a/lib/widgets/fullscreen/fullscreen_page.dart b/lib/widgets/fullscreen/fullscreen_page.dart
index 751a589bf..fdeab3a67 100644
--- a/lib/widgets/fullscreen/fullscreen_page.dart
+++ b/lib/widgets/fullscreen/fullscreen_page.dart
@@ -61,13 +61,13 @@ class FullscreenBodyState extends State<FullscreenBody> with SingleTickerProvide
   bool _isInitialScale = true;
   int _currentHorizontalPage, _currentVerticalPage = imagePage;
   PageController _horizontalPager, _verticalPager;
-  ValueNotifier<bool> _overlayVisible = ValueNotifier(true);
+  final ValueNotifier<bool> _overlayVisible = ValueNotifier(true);
   AnimationController _overlayAnimationController;
   Animation<double> _topOverlayScale;
   Animation<Offset> _bottomOverlayOffset;
   EdgeInsets _frozenViewInsets, _frozenViewPadding;
   FullscreenActionDelegate _actionDelegate;
-  List<Tuple2<String, VideoPlayerController>> _videoControllers = List();
+  final List<Tuple2<String, VideoPlayerController>> _videoControllers = [];
 
   ImageCollection get collection => widget.collection;
 
@@ -85,14 +85,14 @@ class FullscreenBodyState extends State<FullscreenBody> with SingleTickerProvide
     _horizontalPager = PageController(initialPage: _currentHorizontalPage);
     _verticalPager = PageController(initialPage: _currentVerticalPage);
     _overlayAnimationController = AnimationController(
-      duration: Duration(milliseconds: 400),
+      duration: const Duration(milliseconds: 400),
       vsync: this,
     );
     _topOverlayScale = CurvedAnimation(
       parent: _overlayAnimationController,
       curve: Curves.easeOutQuart,
     );
-    _bottomOverlayOffset = Tween(begin: Offset(0, 1), end: Offset(0, 0)).animate(CurvedAnimation(
+    _bottomOverlayOffset = Tween(begin: const Offset(0, 1), end: const Offset(0, 0)).animate(CurvedAnimation(
       parent: _overlayAnimationController,
       curve: Curves.easeOutQuart,
     ));
@@ -105,7 +105,7 @@ class FullscreenBodyState extends State<FullscreenBody> with SingleTickerProvide
     _initOverlay();
   }
 
-  _initOverlay() async {
+  Future<void> _initOverlay() async {
     // wait for MaterialPageRoute.transitionDuration
     // to show overlay after hero animation is complete
     await Future.delayed(Duration(milliseconds: (300 * timeDilation).toInt()));
@@ -136,10 +136,10 @@ class FullscreenBodyState extends State<FullscreenBody> with SingleTickerProvide
           PageView(
             scrollDirection: Axis.vertical,
             controller: _verticalPager,
-            physics: _isInitialScale ? PageScrollPhysics() : NeverScrollableScrollPhysics(),
+            physics: _isInitialScale ? const PageScrollPhysics() : const NeverScrollableScrollPhysics(),
             onPageChanged: _onVerticalPageChanged,
             children: [
-              SizedBox(),
+              const SizedBox(),
               Container(
                 color: Colors.black,
                 child: ImagePage(
@@ -208,12 +208,12 @@ class FullscreenBodyState extends State<FullscreenBody> with SingleTickerProvide
   Future<void> _goToVerticalPage(int page) {
     return _verticalPager.animateToPage(
       page,
-      duration: Duration(milliseconds: 350),
+      duration: const Duration(milliseconds: 350),
       curve: Curves.easeInOut,
     );
   }
 
-  void _onVerticalPageChanged(page) {
+  void _onVerticalPageChanged(int page) {
     setState(() => _currentVerticalPage = page);
     if (_currentVerticalPage == transitionPage) {
       _onLeave();
diff --git a/lib/widgets/fullscreen/image_page.dart b/lib/widgets/fullscreen/image_page.dart
index 117e74a69..c620415d2 100644
--- a/lib/widgets/fullscreen/image_page.dart
+++ b/lib/widgets/fullscreen/image_page.dart
@@ -51,7 +51,7 @@ class ImagePageState extends State<ImagePage> with AutomaticKeepAliveClientMixin
                       entry: entry,
                       controller: videoController,
                     )
-                  : SizedBox(),
+                  : const SizedBox(),
               childSize: mqSize,
               // no hero as most videos fullscreen image is different from its thumbnail
               minScale: PhotoViewComputedScale.contained,
@@ -70,14 +70,14 @@ class ImagePageState extends State<ImagePage> with AutomaticKeepAliveClientMixin
             onTapUp: (tapContext, details, value) => widget.onTap?.call(),
           );
         },
-        loadingChild: Center(
+        loadingChild: const Center(
           child: CircularProgressIndicator(),
         ),
         backgroundDecoration: BoxDecoration(color: Colors.transparent),
         pageController: widget.pageController,
         onPageChanged: widget.onPageChanged,
         scaleStateChangedCallback: widget.onScaleChanged,
-        scrollPhysics: BouncingScrollPhysics(),
+        scrollPhysics: const BouncingScrollPhysics(),
       ),
     );
   }
diff --git a/lib/widgets/fullscreen/info/info_page.dart b/lib/widgets/fullscreen/info/info_page.dart
index d0d839b12..e72ba39f9 100644
--- a/lib/widgets/fullscreen/info/info_page.dart
+++ b/lib/widgets/fullscreen/info/info_page.dart
@@ -119,7 +119,7 @@ class SectionRow extends StatelessWidget {
           padding: const EdgeInsets.all(16.0),
           child: Text(
             title,
-            style: TextStyle(
+            style: const TextStyle(
               fontSize: 20,
               fontFamily: 'Concourse Caps',
             ),
@@ -142,9 +142,9 @@ class InfoRow extends StatelessWidget {
       padding: const EdgeInsets.symmetric(vertical: 4.0),
       child: RichText(
         text: TextSpan(
-          style: TextStyle(fontFamily: 'Concourse'),
+          style: const TextStyle(fontFamily: 'Concourse'),
           children: [
-            TextSpan(text: '$label    ', style: TextStyle(color: Colors.white70)),
+            TextSpan(text: '$label    ', style: const TextStyle(color: Colors.white70)),
             TextSpan(text: value),
           ],
         ),
diff --git a/lib/widgets/fullscreen/info/location_section.dart b/lib/widgets/fullscreen/info/location_section.dart
index aa5f9252c..decb77ed8 100644
--- a/lib/widgets/fullscreen/info/location_section.dart
+++ b/lib/widgets/fullscreen/info/location_section.dart
@@ -7,7 +7,7 @@ import 'package:google_maps_flutter/google_maps_flutter.dart';
 
 class LocationSection extends AnimatedWidget {
   final ImageEntry entry;
-  final showTitle;
+  final bool showTitle;
 
   LocationSection({
     Key key,
@@ -23,12 +23,12 @@ class LocationSection extends AnimatedWidget {
   @override
   Widget build(BuildContext context) {
     return !entry.hasGps
-        ? SizedBox.shrink()
+        ? const SizedBox.shrink()
         : Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
               if (showTitle)
-                Padding(
+                const Padding(
                   padding: EdgeInsets.only(bottom: 8),
                   child: SectionRow('Location'),
                 ),
@@ -43,7 +43,7 @@ class LocationSection extends AnimatedWidget {
               ),
               if (entry.isLocated)
                 Padding(
-                  padding: EdgeInsets.only(top: 8),
+                  padding: const EdgeInsets.only(top: 8),
                   child: InfoRow('Address', entry.addressDetails.addressLine),
                 ),
             ],
@@ -90,7 +90,7 @@ class ImageMapState extends State<ImageMap> with AutomaticKeepAliveClientMixin {
           child: SizedBox(
             height: 200,
             child: ClipRRect(
-              borderRadius: BorderRadius.all(
+              borderRadius: const BorderRadius.all(
                 Radius.circular(16),
               ),
               child: GoogleMap(
@@ -104,18 +104,18 @@ class ImageMapState extends State<ImageMap> with AutomaticKeepAliveClientMixin {
                 zoomGesturesEnabled: false,
                 tiltGesturesEnabled: false,
                 myLocationButtonEnabled: false,
-                markers: [
+                markers: {
                   Marker(
                     markerId: MarkerId(widget.markerId),
                     icon: BitmapDescriptor.defaultMarkerWithHue(accentHue),
                     position: widget.latLng,
                   )
-                ].toSet(),
+                },
               ),
             ),
           ),
         ),
-        SizedBox(width: 8),
+        const SizedBox(width: 8),
         Column(children: [
           IconButton(
             icon: Icon(Icons.add),
@@ -137,7 +137,7 @@ class ImageMapState extends State<ImageMap> with AutomaticKeepAliveClientMixin {
     );
   }
 
-  _zoomBy(double amount) {
+  void _zoomBy(double amount) {
     settings.infoMapZoom += amount;
     _controller.animateCamera(CameraUpdate.zoomBy(amount));
   }
diff --git a/lib/widgets/fullscreen/info/metadata_section.dart b/lib/widgets/fullscreen/info/metadata_section.dart
index 34c1616a1..096079a22 100644
--- a/lib/widgets/fullscreen/info/metadata_section.dart
+++ b/lib/widgets/fullscreen/info/metadata_section.dart
@@ -23,16 +23,16 @@ class MetadataSectionState extends State<MetadataSection> {
   @override
   void initState() {
     super.initState();
-    initMetadataLoader();
+    _initMetadataLoader();
   }
 
   @override
   void didUpdateWidget(MetadataSection oldWidget) {
     super.didUpdateWidget(oldWidget);
-    initMetadataLoader();
+    _initMetadataLoader();
   }
 
-  initMetadataLoader() async {
+  Future<void> _initMetadataLoader() async {
     _metadataLoader = MetadataService.getAllMetadata(widget.entry);
   }
 
@@ -43,9 +43,9 @@ class MetadataSectionState extends State<MetadataSection> {
       builder: (c, mqWidth, child) => FutureBuilder(
         future: _metadataLoader,
         builder: (futureContext, AsyncSnapshot<Map> snapshot) {
-          if (snapshot.hasError) return Text(snapshot.error);
-          if (snapshot.connectionState != ConnectionState.done) return SizedBox.shrink();
           final metadataMap = snapshot.data.cast<String, Map>();
+          if (snapshot.hasError) return Text(snapshot.error.toString());
+          if (snapshot.connectionState != ConnectionState.done) return const SizedBox.shrink();
           final directoryNames = metadataMap.keys.toList()..sort();
 
           Widget content;
@@ -68,7 +68,7 @@ class MetadataSectionState extends State<MetadataSection> {
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
                 Expanded(child: getMetadataColumn(metadataMap, first)),
-                SizedBox(width: 8),
+                const SizedBox(width: 8),
                 Expanded(child: getMetadataColumn(metadataMap, second)),
               ],
             );
@@ -79,7 +79,7 @@ class MetadataSectionState extends State<MetadataSection> {
           return Column(
             crossAxisAlignment: CrossAxisAlignment.stretch,
             children: [
-              SectionRow('Metadata'),
+              const SectionRow('Metadata'),
               content,
             ],
           );
@@ -98,19 +98,19 @@ class MetadataSectionState extends State<MetadataSection> {
           return [
             if (directoryName.isNotEmpty)
               Padding(
-                padding: EdgeInsets.symmetric(vertical: 4.0),
+                padding: const EdgeInsets.symmetric(vertical: 4.0),
                 child: Text(directoryName,
-                    style: TextStyle(
+                    style: const TextStyle(
                       fontSize: 18,
                       fontFamily: 'Concourse Caps',
                     )),
               ),
             ...tagKeys.map((tagKey) {
               final value = directory[tagKey] as String;
-              if (value == null || value.isEmpty) return SizedBox.shrink();
+              if (value == null || value.isEmpty) return const SizedBox.shrink();
               return InfoRow(tagKey, value.length > maxValueLength ? '${value.substring(0, maxValueLength)}…' : value);
             }),
-            SizedBox(height: 16),
+            const SizedBox(height: 16),
           ];
         }),
       ],
diff --git a/lib/widgets/fullscreen/info/xmp_section.dart b/lib/widgets/fullscreen/info/xmp_section.dart
index ada5266f9..83c580047 100644
--- a/lib/widgets/fullscreen/info/xmp_section.dart
+++ b/lib/widgets/fullscreen/info/xmp_section.dart
@@ -18,15 +18,15 @@ class XmpTagSection extends AnimatedWidget {
   Widget build(BuildContext context) {
     final tags = entry.xmpSubjects;
     return tags.isEmpty
-        ? SizedBox.shrink()
+        ? const SizedBox.shrink()
         : Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
-              SectionRow('XMP Tags'),
+              const SectionRow('XMP Tags'),
               Wrap(
                 children: tags
                     .map((tag) => Padding(
-                          padding: EdgeInsets.symmetric(horizontal: 4.0),
+                          padding: const EdgeInsets.symmetric(horizontal: 4.0),
                           child: ActionChip(
                             label: Text(tag),
                             onPressed: () => Navigator.push(
diff --git a/lib/widgets/fullscreen/overlay/bottom.dart b/lib/widgets/fullscreen/overlay/bottom.dart
index 606d7aa76..77a43fd79 100644
--- a/lib/widgets/fullscreen/overlay/bottom.dart
+++ b/lib/widgets/fullscreen/overlay/bottom.dart
@@ -45,16 +45,16 @@ class _FullscreenBottomOverlayState extends State<FullscreenBottomOverlay> {
   @override
   void initState() {
     super.initState();
-    initDetailLoader();
+    _initDetailLoader();
   }
 
   @override
   void didUpdateWidget(FullscreenBottomOverlay oldWidget) {
     super.didUpdateWidget(oldWidget);
-    initDetailLoader();
+    _initDetailLoader();
   }
 
-  initDetailLoader() {
+  void _initDetailLoader() {
     _detailLoader = MetadataService.getOverlayMetadata(entry);
   }
 
@@ -86,7 +86,7 @@ class _FullscreenBottomOverlayState extends State<FullscreenBottomOverlay> {
                       _lastEntry = entry;
                     }
                     return _lastEntry == null
-                        ? SizedBox.shrink()
+                        ? const SizedBox.shrink()
                         : _FullscreenBottomOverlayContent(
                             entry: _lastEntry,
                             details: _lastDetails,
@@ -115,7 +115,7 @@ class _FullscreenBottomOverlayContent extends StatelessWidget {
   final String position;
   final double maxWidth;
 
-  _FullscreenBottomOverlayContent({
+  const _FullscreenBottomOverlayContent({
     this.entry,
     this.details,
     this.position,
diff --git a/lib/widgets/fullscreen/overlay/top.dart b/lib/widgets/fullscreen/overlay/top.dart
index 576ada268..61f0a70d8 100644
--- a/lib/widgets/fullscreen/overlay/top.dart
+++ b/lib/widgets/fullscreen/overlay/top.dart
@@ -28,14 +28,14 @@ class FullscreenTopOverlay extends StatelessWidget {
     return SafeArea(
       minimum: (viewInsets ?? EdgeInsets.zero) + (viewPadding ?? EdgeInsets.zero),
       child: Padding(
-        padding: EdgeInsets.all(8.0),
+        padding: const EdgeInsets.all(8.0),
         child: Row(
           children: [
             OverlayButton(
               scale: scale,
-              child: BackButton(),
+              child: const BackButton(),
             ),
-            Spacer(),
+            const Spacer(),
             OverlayButton(
               scale: scale,
               child: IconButton(
@@ -44,7 +44,7 @@ class FullscreenTopOverlay extends StatelessWidget {
                 tooltip: 'Share',
               ),
             ),
-            SizedBox(width: 8),
+            const SizedBox(width: 8),
             OverlayButton(
               scale: scale,
               child: IconButton(
@@ -53,7 +53,7 @@ class FullscreenTopOverlay extends StatelessWidget {
                 tooltip: 'Delete',
               ),
             ),
-            SizedBox(width: 8),
+            const SizedBox(width: 8),
             OverlayButton(
               scale: scale,
               child: PopupMenuButton<FullscreenAction>(
@@ -81,21 +81,21 @@ class FullscreenTopOverlay extends StatelessWidget {
                       value: FullscreenAction.print,
                       child: MenuRow(text: 'Print', icon: Icons.print),
                     ),
-                  PopupMenuDivider(),
-                  PopupMenuItem(
+                  const PopupMenuDivider(),
+                  const PopupMenuItem(
                     value: FullscreenAction.edit,
                     child: Text('Edit with…'),
                   ),
-                  PopupMenuItem(
+                  const PopupMenuItem(
                     value: FullscreenAction.open,
                     child: Text('Open with…'),
                   ),
-                  PopupMenuItem(
+                  const PopupMenuItem(
                     value: FullscreenAction.setAs,
                     child: Text('Set as…'),
                   ),
                   if (entry.hasGps)
-                    PopupMenuItem(
+                    const PopupMenuItem(
                       value: FullscreenAction.openMap,
                       child: Text('Show on map…'),
                     ),
diff --git a/lib/widgets/fullscreen/overlay/video.dart b/lib/widgets/fullscreen/overlay/video.dart
index 7d9354f12..24734c1b9 100644
--- a/lib/widgets/fullscreen/overlay/video.dart
+++ b/lib/widgets/fullscreen/overlay/video.dart
@@ -46,32 +46,32 @@ class VideoControlOverlayState extends State<VideoControlOverlay> with SingleTic
   void initState() {
     super.initState();
     _playPauseAnimation = AnimationController(
-      duration: Duration(milliseconds: 300),
+      duration: const Duration(milliseconds: 300),
       vsync: this,
     );
-    registerWidget(widget);
+    _registerWidget(widget);
     _onValueChange();
   }
 
   @override
   void didUpdateWidget(VideoControlOverlay oldWidget) {
     super.didUpdateWidget(oldWidget);
-    unregisterWidget(oldWidget);
-    registerWidget(widget);
+    _unregisterWidget(oldWidget);
+    _registerWidget(widget);
   }
 
   @override
   void dispose() {
-    unregisterWidget(widget);
+    _unregisterWidget(widget);
     _playPauseAnimation.dispose();
     super.dispose();
   }
 
-  void registerWidget(VideoControlOverlay widget) {
+  void _registerWidget(VideoControlOverlay widget) {
     widget.controller.addListener(_onValueChange);
   }
 
-  void unregisterWidget(VideoControlOverlay widget) {
+  void _unregisterWidget(VideoControlOverlay widget) {
     widget.controller.removeListener(_onValueChange);
   }
 
@@ -86,7 +86,7 @@ class VideoControlOverlayState extends State<VideoControlOverlay> with SingleTic
 
         final viewInsets = widget.viewInsets ?? mqViewInsets;
         final viewPadding = widget.viewPadding ?? mqViewPadding;
-        final safePadding = (viewInsets + viewPadding).copyWith(bottom: 8) + EdgeInsets.symmetric(horizontal: 8.0);
+        final safePadding = (viewInsets + viewPadding).copyWith(bottom: 8) + const EdgeInsets.symmetric(horizontal: 8.0);
 
         return Padding(
           padding: safePadding,
@@ -109,7 +109,7 @@ class VideoControlOverlayState extends State<VideoControlOverlay> with SingleTic
                       Expanded(
                         child: _buildProgressBar(),
                       ),
-                      SizedBox(width: 8),
+                      const SizedBox(width: 8),
                       OverlayButton(
                         scale: scale,
                         child: IconButton(
@@ -130,7 +130,7 @@ class VideoControlOverlayState extends State<VideoControlOverlay> with SingleTic
   }
 
   Widget _buildProgressBar() {
-    final progressBarBorderRadius = 123.0;
+    const progressBarBorderRadius = 123.0;
     return SizeTransition(
       sizeFactor: scale,
       child: BlurredRRect(
@@ -150,11 +150,11 @@ class VideoControlOverlayState extends State<VideoControlOverlay> with SingleTic
             if (_playingOnDragStart) controller.play();
           },
           child: Container(
-            padding: EdgeInsets.symmetric(vertical: 4, horizontal: 16) + EdgeInsets.only(bottom: 16),
+            padding: const EdgeInsets.symmetric(vertical: 4, horizontal: 16) + const EdgeInsets.only(bottom: 16),
             decoration: BoxDecoration(
               color: Colors.black26,
               border: Border.all(color: Colors.white30, width: 0.5),
-              borderRadius: BorderRadius.all(
+              borderRadius: const BorderRadius.all(
                 Radius.circular(progressBarBorderRadius),
               ),
             ),
@@ -164,7 +164,7 @@ class VideoControlOverlayState extends State<VideoControlOverlay> with SingleTic
                 Row(
                   children: [
                     Text(formatDuration(value.position ?? Duration.zero)),
-                    Spacer(),
+                    const Spacer(),
                     Text(formatDuration(value.duration ?? Duration.zero)),
                   ],
                 ),
diff --git a/lib/widgets/fullscreen/video.dart b/lib/widgets/fullscreen/video.dart
index 74cd4bba4..2e12a2050 100644
--- a/lib/widgets/fullscreen/video.dart
+++ b/lib/widgets/fullscreen/video.dart
@@ -29,34 +29,34 @@ class AvesVideoState extends State<AvesVideo> {
   @override
   void initState() {
     super.initState();
-    registerWidget(widget);
+    _registerWidget(widget);
     _onValueChange();
   }
 
   @override
   void didUpdateWidget(AvesVideo oldWidget) {
     super.didUpdateWidget(oldWidget);
-    unregisterWidget(oldWidget);
-    registerWidget(widget);
+    _unregisterWidget(oldWidget);
+    _registerWidget(widget);
   }
 
   @override
   void dispose() {
-    unregisterWidget(widget);
+    _unregisterWidget(widget);
     super.dispose();
   }
 
-  registerWidget(AvesVideo widget) {
+  void _registerWidget(AvesVideo widget) {
     widget.controller.addListener(_onValueChange);
   }
 
-  unregisterWidget(AvesVideo widget) {
+  void _unregisterWidget(AvesVideo widget) {
     widget.controller.removeListener(_onValueChange);
   }
 
   @override
   Widget build(BuildContext context) {
-    if (value == null) return SizedBox();
+    if (value == null) return const SizedBox();
     if (value.hasError) {
       return Selector<MediaQueryData, double>(
         selector: (c, mq) => mq.size.width,
@@ -79,12 +79,12 @@ class AvesVideoState extends State<AvesVideo> {
     );
   }
 
-  _onValueChange() {
-    if (!value.isPlaying && value.position == value.duration) goToBeginning();
+  void _onValueChange() {
+    if (!value.isPlaying && value.position == value.duration) _goToStart();
     setState(() {});
   }
 
-  goToBeginning() async {
+  Future<void> _goToStart() async {
     await widget.controller.seekTo(Duration.zero);
     await widget.controller.pause();
   }