multi selection generalization prep

lib/model/selection.dart

@@ -0,0 +1,45 @@
+import 'package:flutter/foundation.dart';
+
+class Selection<T> extends ChangeNotifier {
+  bool _isSelecting = false;
+
+  bool get isSelecting => _isSelecting;
+
+  final Set<T> _selection = {};
+
+  Set<T> get selection => _selection;
+
+  void browse() {
+    clearSelection();
+    _isSelecting = false;
+    notifyListeners();
+  }
+
+  void select() {
+    _isSelecting = true;
+    notifyListeners();
+  }
+
+  bool isSelected(Iterable<T> items) => items.every(selection.contains);
+
+  void addToSelection(Iterable<T> items) {
+    _selection.addAll(items);
+    notifyListeners();
+  }
+
+  void removeFromSelection(Iterable<T> items) {
+    _selection.removeAll(items);
+    notifyListeners();
+  }
+
+  void clearSelection() {
+    _selection.clear();
+    notifyListeners();
+  }
+
+  void toggleSelection(T item) {
+    if (_selection.isEmpty) select();
+    if (!_selection.remove(item)) _selection.add(item);
+    notifyListeners();
+  }
+}

lib/model/source/collection_lens.dart

@@ -18,7 +18,7 @@ import 'package:flutter/foundation.dart';
 
 import 'enums.dart';
 
-class CollectionLens with ChangeNotifier, CollectionActivityMixin {
+class CollectionLens with ChangeNotifier {
   final CollectionSource source;
   final Set<CollectionFilter> filters;
   EntryGroupFactor groupFactor;
@@ -213,55 +213,6 @@ class CollectionLens with ChangeNotifier, CollectionActivityMixin {
     _sortedEntries?.removeWhere(entries.contains);
     sections.forEach((key, sectionEntries) => sectionEntries.removeWhere(entries.contains));
     sections = Map.unmodifiable(Map.fromEntries(sections.entries.where((kv) => kv.value.isNotEmpty)));
-    selection.removeAll(entries);
     notifyListeners();
   }
 }
-
-mixin CollectionActivityMixin {
-  final ValueNotifier<Activity> _activityNotifier = ValueNotifier(Activity.browse);
-
-  ValueNotifier<Activity> get activityNotifier => _activityNotifier;
-
-  bool get isBrowsing => _activityNotifier.value == Activity.browse;
-
-  bool get isSelecting => _activityNotifier.value == Activity.select;
-
-  void browse() {
-    clearSelection();
-    _activityNotifier.value = Activity.browse;
-  }
-
-  void select() => _activityNotifier.value = Activity.select;
-
-  // selection
-
-  final AChangeNotifier selectionChangeNotifier = AChangeNotifier();
-
-  final Set<AvesEntry> _selection = {};
-
-  Set<AvesEntry> get selection => _selection;
-
-  bool isSelected(Iterable<AvesEntry> entries) => entries.every(selection.contains);
-
-  void addToSelection(Iterable<AvesEntry> entries) {
-    _selection.addAll(entries);
-    selectionChangeNotifier.notifyListeners();
-  }
-
-  void removeFromSelection(Iterable<AvesEntry> entries) {
-    _selection.removeAll(entries);
-    selectionChangeNotifier.notifyListeners();
-  }
-
-  void clearSelection() {
-    _selection.clear();
-    selectionChangeNotifier.notifyListeners();
-  }
-
-  void toggleSelection(AvesEntry entry) {
-    if (_selection.isEmpty) select();
-    if (!_selection.remove(entry)) _selection.add(entry);
-    selectionChangeNotifier.notifyListeners();
-  }
-}

lib/model/source/enums.dart

@@ -1,5 +1,3 @@
-enum Activity { browse, select }
-
 enum SourceState { loading, cataloguing, locating, ready }
 
 enum ChipSortFactor { date, name, count }

lib/widgets/collection/app_bar.dart

@@ -5,6 +5,7 @@ import 'package:aves/model/actions/collection_actions.dart';
 import 'package:aves/model/actions/entry_actions.dart';
 import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/filters.dart';
+import 'package:aves/model/selection.dart';
 import 'package:aves/model/settings/settings.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/model/source/collection_source.dart';
@@ -49,6 +50,7 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
   final EntrySetActionDelegate _actionDelegate = EntrySetActionDelegate();
   late AnimationController _browseToSelectAnimation;
   late Future<bool> _canAddShortcutsLoader;
+  final ValueNotifier<bool> _isSelectingNotifier = ValueNotifier(false);
 
   CollectionLens get collection => widget.collection;
 
@@ -63,6 +65,7 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
       duration: Durations.iconAnimation,
       vsync: this,
     );
+    _isSelectingNotifier.addListener(_onActivityChange);
     _canAddShortcutsLoader = AppShortcutService.canPin();
     _registerWidget(widget);
     WidgetsBinding.instance!.addPostFrameCallback((_) => _updateHeight());
@@ -78,35 +81,35 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
   @override
   void dispose() {
     _unregisterWidget(widget);
+    _isSelectingNotifier.removeListener(_onActivityChange);
     _browseToSelectAnimation.dispose();
     _searchFieldController.dispose();
     super.dispose();
   }
 
   void _registerWidget(CollectionAppBar widget) {
-    widget.collection.activityNotifier.addListener(_onActivityChange);
     widget.collection.filterChangeNotifier.addListener(_updateHeight);
   }
 
   void _unregisterWidget(CollectionAppBar widget) {
-    widget.collection.activityNotifier.removeListener(_onActivityChange);
     widget.collection.filterChangeNotifier.removeListener(_updateHeight);
   }
 
   @override
   Widget build(BuildContext context) {
     final appMode = context.watch<ValueNotifier<AppMode>>().value;
-    return ValueListenableBuilder<Activity>(
+    return Selector<Selection<AvesEntry>, bool>(
-      valueListenable: collection.activityNotifier,
+      selector: (context, selection) => selection.isSelecting,
-      builder: (context, activity, child) {
+      builder: (context, isSelecting, child) {
+        _isSelectingNotifier.value = isSelecting;
         return AnimatedBuilder(
           animation: collection.filterChangeNotifier,
           builder: (context, child) {
             final removableFilters = appMode != AppMode.pickInternal;
             return SliverAppBar(
-              leading: appMode.hasDrawer ? _buildAppBarLeading() : null,
+              leading: appMode.hasDrawer ? _buildAppBarLeading(isSelecting) : null,
-              title: _buildAppBarTitle(),
+              title: _buildAppBarTitle(isSelecting),
-              actions: _buildActions(),
+              actions: _buildActions(isSelecting),
               bottom: hasFilters
                   ? FilterBar(
                       filters: collection.filters,
@@ -123,15 +126,15 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
     );
   }
 
-  Widget _buildAppBarLeading() {
+  Widget _buildAppBarLeading(bool isSelecting) {
     VoidCallback? onPressed;
     String? tooltip;
-    if (collection.isBrowsing) {
+    if (isSelecting) {
+      onPressed = () => context.read<Selection<AvesEntry>>().browse();
+      tooltip = MaterialLocalizations.of(context).backButtonTooltip;
+    } else {
       onPressed = Scaffold.of(context).openDrawer;
       tooltip = MaterialLocalizations.of(context).openAppDrawerTooltip;
-    } else if (collection.isSelecting) {
-      onPressed = collection.browse;
-      tooltip = MaterialLocalizations.of(context).backButtonTooltip;
     }
     return IconButton(
       key: const Key('appbar-leading-button'),
@@ -144,8 +147,13 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
     );
   }
 
-  Widget? _buildAppBarTitle() {
+  Widget? _buildAppBarTitle(bool isSelecting) {
-    if (collection.isBrowsing) {
+    if (isSelecting) {
+      return Selector<Selection<AvesEntry>, int>(
+        selector: (context, selection) => selection.selection.length,
+        builder: (context, count, child) => Text(context.l10n.collectionSelectionPageTitle(count)),
+      );
+    } else {
       final appMode = context.watch<ValueNotifier<AppMode>>().value;
       Widget title = Text(appMode.isPicking ? context.l10n.collectionPickPageTitle : context.l10n.collectionPageTitle);
       if (appMode == AppMode.main) {
@@ -158,36 +166,25 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
         onTap: appMode.canSearch ? _goToSearch : null,
         child: title,
       );
-    } else if (collection.isSelecting) {
-      return AnimatedBuilder(
-        animation: collection.selectionChangeNotifier,
-        builder: (context, child) {
-          final count = collection.selection.length;
-          return Text(context.l10n.collectionSelectionPageTitle(count));
-        },
-      );
     }
-    return null;
   }
 
-  List<Widget> _buildActions() {
+  List<Widget> _buildActions(bool isSelecting) {
     final appMode = context.watch<ValueNotifier<AppMode>>().value;
     return [
-      if (collection.isBrowsing && appMode.canSearch)
+      if (!isSelecting && appMode.canSearch)
         CollectionSearchButton(
           source: source,
           parentCollection: collection,
         ),
-      if (collection.isSelecting)
+      if (isSelecting)
-        ...EntryActions.selection.map((action) => AnimatedBuilder(
+        ...EntryActions.selection.map((action) => Selector<Selection<AvesEntry>, bool>(
-              animation: collection.selectionChangeNotifier,
+              selector: (context, selection) => selection.selection.isEmpty,
-              builder: (context, child) {
+              builder: (context, isEmpty, child) => IconButton(
-                return IconButton(
                 icon: Icon(action.getIcon()),
-                  onPressed: collection.selection.isEmpty ? null : () => _actionDelegate.onEntryActionSelected(context, action),
+                onPressed: isEmpty ? null : () => _actionDelegate.onEntryActionSelected(context, action),
                 tooltip: action.getText(context),
-                );
+              ),
-              },
             )),
       FutureBuilder<bool>(
         future: _canAddShortcutsLoader,
@@ -196,8 +193,9 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
           return PopupMenuButton<CollectionAction>(
             key: const Key('appbar-menu-button'),
             itemBuilder: (context) {
+              final selection = context.read<Selection<AvesEntry>>();
               final isNotEmpty = !collection.isEmpty;
-              final hasSelection = collection.selection.isNotEmpty;
+              final hasSelection = selection.selection.isNotEmpty;
               return [
                 PopupMenuItem(
                   key: const Key('menu-sort'),
@@ -210,7 +208,7 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
                     value: CollectionAction.group,
                     child: MenuRow(text: context.l10n.menuActionGroup, icon: AIcons.group),
                   ),
-                if (collection.isBrowsing && appMode == AppMode.main) ...[
+                if (!selection.isSelecting && appMode == AppMode.main) ...[
                   PopupMenuItem(
                     value: CollectionAction.select,
                     enabled: isNotEmpty,
@@ -227,7 +225,7 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
                       child: MenuRow(text: context.l10n.collectionActionAddShortcut, icon: AIcons.addShortcut),
                     ),
                 ],
-                if (collection.isSelecting) ...[
+                if (selection.isSelecting) ...[
                   const PopupMenuDivider(),
                   PopupMenuItem(
                     value: CollectionAction.copy,
@@ -247,7 +245,7 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
                   const PopupMenuDivider(),
                   PopupMenuItem(
                     value: CollectionAction.selectAll,
-                    enabled: collection.selection.length < collection.entryCount,
+                    enabled: selection.selection.length < collection.entryCount,
                     child: MenuRow(text: context.l10n.collectionActionSelectAll),
                   ),
                   PopupMenuItem(
@@ -269,7 +267,7 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
   }
 
   void _onActivityChange() {
-    if (collection.isSelecting) {
+    if (context.read<Selection<AvesEntry>>().isSelecting) {
       _browseToSelectAnimation.forward();
     } else {
       _browseToSelectAnimation.reverse();
@@ -289,13 +287,13 @@ class _CollectionAppBarState extends State<CollectionAppBar> with SingleTickerPr
         _actionDelegate.onCollectionActionSelected(context, action);
         break;
       case CollectionAction.select:
-        collection.select();
+        context.read<Selection<AvesEntry>>().select();
         break;
       case CollectionAction.selectAll:
-        collection.addToSelection(collection.sortedEntries);
+        context.read<Selection<AvesEntry>>().addToSelection(collection.sortedEntries);
         break;
       case CollectionAction.selectNone:
-        collection.clearSelection();
+        context.read<Selection<AvesEntry>>().clearSelection();
         break;
       case CollectionAction.stats:
         _goToStats();

lib/widgets/collection/collection_grid.dart

@@ -12,7 +12,6 @@ import 'package:aves/theme/icons.dart';
 import 'package:aves/widgets/collection/app_bar.dart';
 import 'package:aves/widgets/collection/draggable_thumb_label.dart';
 import 'package:aves/widgets/collection/grid/section_layout.dart';
-import 'package:aves/widgets/collection/grid/selector.dart';
 import 'package:aves/widgets/collection/grid/thumbnail.dart';
 import 'package:aves/widgets/collection/thumbnail/decorated.dart';
 import 'package:aves/widgets/collection/thumbnail/theme.dart';
@@ -22,6 +21,7 @@ import 'package:aves/widgets/common/behaviour/sloppy_scroll_physics.dart';
 import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/common/extensions/media_query.dart';
 import 'package:aves/widgets/common/grid/item_tracker.dart';
+import 'package:aves/widgets/common/grid/selector.dart';
 import 'package:aves/widgets/common/grid/sliver.dart';
 import 'package:aves/widgets/common/identity/empty.dart';
 import 'package:aves/widgets/common/identity/scroll_thumb.dart';
@@ -173,7 +173,7 @@ class _CollectionSectionedContentState extends State<_CollectionSectionedContent
     final isMainMode = context.select<ValueNotifier<AppMode>, bool>((vn) => vn.value == AppMode.main);
     final selector = GridSelectionGestureDetector(
       selectable: isMainMode,
-      collection: collection,
+      entries: collection.sortedEntries,
       scrollController: scrollController,
       appBarHeightNotifier: appBarHeightNotifier,
       child: scaler,

lib/widgets/collection/collection_page.dart

@@ -1,8 +1,11 @@
+import 'package:aves/model/entry.dart';
+import 'package:aves/model/selection.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/widgets/collection/collection_grid.dart';
 import 'package:aves/widgets/common/basic/insets.dart';
 import 'package:aves/widgets/common/behaviour/double_back_pop.dart';
 import 'package:aves/widgets/common/providers/media_query_data_provider.dart';
+import 'package:aves/widgets/common/providers/selection_provider.dart';
 import 'package:aves/widgets/drawer/app_drawer.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
@@ -35,10 +38,13 @@ class _CollectionPageState extends State<CollectionPage> {
   Widget build(BuildContext context) {
     return MediaQueryDataProvider(
       child: Scaffold(
-        body: WillPopScope(
+        body: SelectionProvider<AvesEntry>(
+          child: Builder(
+            builder: (context) => WillPopScope(
               onWillPop: () {
-            if (collection.isSelecting) {
+                final selection = context.read<Selection<AvesEntry>>();
-              collection.browse();
+                if (selection.isSelecting) {
+                  selection.browse();
                   return SynchronousFuture(false);
                 }
                 return SynchronousFuture(true);
@@ -57,6 +63,8 @@ class _CollectionPageState extends State<CollectionPage> {
                 ),
               ),
             ),
+          ),
+        ),
         drawer: const AppDrawer(),
         resizeToAvoidBottomInset: false,
       ),

lib/widgets/collection/entry_set_action_delegate.dart

@@ -3,8 +3,10 @@ import 'dart:async';
 import 'package:aves/model/actions/collection_actions.dart';
 import 'package:aves/model/actions/entry_actions.dart';
 import 'package:aves/model/actions/move_type.dart';
+import 'package:aves/model/entry.dart';
 import 'package:aves/model/filters/album.dart';
 import 'package:aves/model/highlight.dart';
+import 'package:aves/model/selection.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/services/android_app_service.dart';
 import 'package:aves/services/image_op_events.dart';
@@ -31,8 +33,8 @@ class EntrySetActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAware
         _showDeleteDialog(context);
         break;
       case EntryAction.share:
-        final collection = context.read<CollectionLens>();
+        final selection = context.read<Selection<AvesEntry>>().selection;
-        AndroidAppService.shareEntries(collection.selection).then((success) {
+        AndroidAppService.shareEntries(selection).then((success) {
           if (!success) showNoMatchingAppDialog(context);
         });
         break;
@@ -59,16 +61,18 @@ class EntrySetActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAware
 
   void _refreshMetadata(BuildContext context) {
     final collection = context.read<CollectionLens>();
-    collection.source.refreshMetadata(collection.selection);
+    final selection = context.read<Selection<AvesEntry>>();
-    collection.browse();
+    collection.source.refreshMetadata(selection.selection);
+    selection.browse();
   }
 
   Future<void> _moveSelection(BuildContext context, {required MoveType moveType}) async {
     final collection = context.read<CollectionLens>();
     final source = collection.source;
-    final selection = collection.selection;
+    final selection = context.read<Selection<AvesEntry>>();
+    final selectedItems = selection.selection;
 
-    final selectionDirs = selection.map((e) => e.directory).whereNotNull().toSet();
+    final selectionDirs = selectedItems.map((e) => e.directory).whereNotNull().toSet();
     if (moveType == MoveType.move) {
       // check whether moving is possible given OS restrictions,
       // before asking to pick a destination album
@@ -95,11 +99,11 @@ class EntrySetActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAware
 
     if (moveType == MoveType.move && !await checkStoragePermissionForAlbums(context, selectionDirs)) return;
 
-    if (!await checkFreeSpaceForMove(context, selection, destinationAlbum, moveType)) return;
+    if (!await checkFreeSpaceForMove(context, selectedItems, destinationAlbum, moveType)) return;
 
     // do not directly use selection when moving and post-processing items
     // as source monitoring may remove obsolete items from the original selection
-    final todoEntries = selection.toSet();
+    final todoEntries = selectedItems.toSet();
 
     final copy = moveType == MoveType.copy;
     final todoCount = todoEntries.length;
@@ -118,7 +122,7 @@ class EntrySetActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAware
           destinationAlbum: destinationAlbum,
           movedOps: movedOps,
         );
-        collection.browse();
+        selection.browse();
         source.resumeMonitoring();
 
         // cleanup
@@ -177,9 +181,10 @@ class EntrySetActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAware
   Future<void> _showDeleteDialog(BuildContext context) async {
     final collection = context.read<CollectionLens>();
     final source = collection.source;
-    final selection = collection.selection;
+    final selection = context.read<Selection<AvesEntry>>();
-    final selectionDirs = selection.map((e) => e.directory).whereNotNull().toSet();
+    final selectedItems = selection.selection;
-    final todoCount = selection.length;
+    final selectionDirs = selectedItems.map((e) => e.directory).whereNotNull().toSet();
+    final todoCount = selectedItems.length;
 
     final confirmed = await showDialog<bool>(
       context: context,
@@ -207,12 +212,12 @@ class EntrySetActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAware
     source.pauseMonitoring();
     showOpReport<ImageOpEvent>(
       context: context,
-      opStream: imageFileService.delete(selection),
+      opStream: imageFileService.delete(selectedItems),
       itemCount: todoCount,
       onDone: (processed) async {
         final deletedUris = processed.where((event) => event.success).map((event) => event.uri).toSet();
         await source.removeEntries(deletedUris);
-        collection.browse();
+        selection.browse();
         source.resumeMonitoring();
 
         final deletedCount = deletedUris.length;

lib/widgets/collection/grid/thumbnail.dart

@@ -1,5 +1,6 @@
 import 'package:aves/app_mode.dart';
 import 'package:aves/model/entry.dart';
+import 'package:aves/model/selection.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/services/viewer_service.dart';
 import 'package:aves/widgets/collection/thumbnail/decorated.dart';
@@ -31,10 +32,11 @@ class InteractiveThumbnail extends StatelessWidget {
         final appMode = context.read<ValueNotifier<AppMode>>().value;
         switch (appMode) {
           case AppMode.main:
-            if (collection.isBrowsing) {
+            final selection = context.read<Selection<AvesEntry>>();
+            if (selection.isSelecting) {
+              selection.toggleSelection(entry);
+            } else {
               _goToViewer(context);
-            } else if (collection.isSelecting) {
-              collection.toggleSelection(entry);
             }
             break;
           case AppMode.pickExternal:

lib/widgets/collection/thumbnail/overlay.dart

@@ -2,8 +2,7 @@ import 'dart:math';
 
 import 'package:aves/model/entry.dart';
 import 'package:aves/model/highlight.dart';
-import 'package:aves/model/source/collection_lens.dart';
+import 'package:aves/model/selection.dart';
-import 'package:aves/model/source/enums.dart';
 import 'package:aves/theme/durations.dart';
 import 'package:aves/theme/icons.dart';
 import 'package:aves/widgets/collection/thumbnail/theme.dart';
@@ -59,19 +58,15 @@ class ThumbnailSelectionOverlay extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final collection = context.watch<CollectionLens>();
+    final isSelecting = context.select<Selection<AvesEntry>, bool>((selection) => selection.isSelecting);
-    return ValueListenableBuilder<Activity>(
+    final child = isSelecting
-      valueListenable: collection.activityNotifier,
+        ? Selector<Selection<AvesEntry>, bool>(
-      builder: (context, activity, child) {
+            selector: (context, selection) => selection.isSelected([entry]),
-        final child = collection.isSelecting
+            builder: (context, isSelected, child) {
-            ? AnimatedBuilder(
+              var child = isSelecting
-                animation: collection.selectionChangeNotifier,
-                builder: (context, child) {
-                  final selected = collection.isSelected([entry]);
-                  var child = collection.isSelecting
                   ? OverlayIcon(
-                          key: ValueKey(selected),
+                      key: ValueKey(isSelected),
-                          icon: selected ? AIcons.selected : AIcons.unselected,
+                      icon: isSelected ? AIcons.selected : AIcons.unselected,
                       size: context.select<ThumbnailThemeData, double>((t) => t.iconSize),
                     )
                   : const SizedBox.shrink();
@@ -88,7 +83,7 @@ class ThumbnailSelectionOverlay extends StatelessWidget {
               child = AnimatedContainer(
                 duration: duration,
                 alignment: AlignmentDirectional.topEnd,
-                    color: selected ? Colors.black54 : Colors.transparent,
+                color: isSelected ? Colors.black54 : Colors.transparent,
                 child: child,
               );
               return child;
@@ -99,8 +94,6 @@ class ThumbnailSelectionOverlay extends StatelessWidget {
       duration: duration,
       child: child,
     );
-      },
-    );
   }
 }
 

lib/widgets/common/grid/header.dart

@@ -1,5 +1,6 @@
+import 'package:aves/model/entry.dart';
+import 'package:aves/model/selection.dart';
 import 'package:aves/model/source/collection_lens.dart';
-import 'package:aves/model/source/enums.dart';
 import 'package:aves/model/source/section_keys.dart';
 import 'package:aves/theme/durations.dart';
 import 'package:aves/theme/icons.dart';
@@ -79,11 +80,12 @@ class SectionHeader extends StatelessWidget {
   void _toggleSectionSelection(BuildContext context) {
     final collection = context.read<CollectionLens>();
     final sectionEntries = collection.sections[sectionKey]!;
-    final selected = collection.isSelected(sectionEntries);
+    final selection = context.read<Selection<AvesEntry>>();
-    if (selected) {
+    final isSelected = selection.isSelected(sectionEntries);
-      collection.removeFromSelection(sectionEntries);
+    if (isSelected) {
+      selection.removeFromSelection(sectionEntries);
     } else {
-      collection.addToSelection(sectionEntries);
+      selection.addToSelection(sectionEntries);
     }
   }
 
@@ -142,47 +144,14 @@ class _SectionSelectableLeading extends StatelessWidget {
   Widget build(BuildContext context) {
     if (!selectable) return _buildBrowsing(context);
 
-    final collection = context.watch<CollectionLens>();
+    final isSelecting = context.select<Selection<AvesEntry>, bool>((selection) => selection.isSelecting);
-    return ValueListenableBuilder<Activity>(
+    final Widget child = isSelecting
-      valueListenable: collection.activityNotifier,
+        ? _SectionSelectingLeading(
-      builder: (context, activity, child) {
+            sectionKey: sectionKey,
-        final child = collection.isSelecting
-            ? AnimatedBuilder(
-                animation: collection.selectionChangeNotifier,
-                builder: (context, child) {
-                  final sectionEntries = collection.sections[sectionKey]!;
-                  final selected = collection.isSelected(sectionEntries);
-                  final child = TooltipTheme(
-                    key: ValueKey(selected),
-                    data: TooltipTheme.of(context).copyWith(
-                      preferBelow: false,
-                    ),
-                    child: IconButton(
-                      iconSize: 26,
-                      padding: const EdgeInsets.only(top: 1),
-                      alignment: AlignmentDirectional.topStart,
-                      icon: Icon(selected ? AIcons.selected : AIcons.unselected),
             onPressed: onPressed,
-                      tooltip: selected ? context.l10n.collectionDeselectSectionTooltip : context.l10n.collectionSelectSectionTooltip,
-                      constraints: const BoxConstraints(
-                        minHeight: leadingDimension,
-                        minWidth: leadingDimension,
-                      ),
-                    ),
-                  );
-                  return AnimatedSwitcher(
-                    duration: Durations.sectionHeaderAnimation,
-                    switchInCurve: Curves.easeOutBack,
-                    switchOutCurve: Curves.easeOutBack,
-                    transitionBuilder: (child, animation) => ScaleTransition(
-                      scale: animation,
-                      child: child,
-                    ),
-                    child: child,
-                  );
-                },
           )
         : _buildBrowsing(context);
+
     return AnimatedSwitcher(
       duration: Durations.sectionHeaderAnimation,
       switchInCurve: Curves.easeInOut,
@@ -205,9 +174,52 @@ class _SectionSelectableLeading extends StatelessWidget {
       },
       child: child,
     );
-      },
-    );
   }
 
   Widget _buildBrowsing(BuildContext context) => browsingBuilder?.call(context) ?? const SizedBox(height: leadingDimension);
 }
+
+class _SectionSelectingLeading extends StatelessWidget {
+  final SectionKey sectionKey;
+  final VoidCallback? onPressed;
+
+  const _SectionSelectingLeading({
+    Key? key,
+    required this.sectionKey,
+    required this.onPressed,
+  }) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    final sectionEntries = context.watch<CollectionLens>().sections[sectionKey]!;
+    final selection = context.watch<Selection<AvesEntry>>();
+    final isSelected = selection.isSelected(sectionEntries);
+    return AnimatedSwitcher(
+      duration: Durations.sectionHeaderAnimation,
+      switchInCurve: Curves.easeOutBack,
+      switchOutCurve: Curves.easeOutBack,
+      transitionBuilder: (child, animation) => ScaleTransition(
+        scale: animation,
+        child: child,
+      ),
+      child: TooltipTheme(
+        key: ValueKey(isSelected),
+        data: TooltipTheme.of(context).copyWith(
+          preferBelow: false,
+        ),
+        child: IconButton(
+          iconSize: 26,
+          padding: const EdgeInsets.only(top: 1),
+          alignment: AlignmentDirectional.topStart,
+          icon: Icon(isSelected ? AIcons.selected : AIcons.unselected),
+          onPressed: onPressed,
+          tooltip: isSelected ? context.l10n.collectionDeselectSectionTooltip : context.l10n.collectionSelectSectionTooltip,
+          constraints: const BoxConstraints(
+            minHeight: SectionHeader.leadingDimension,
+            minWidth: SectionHeader.leadingDimension,
+          ),
+        ),
+      ),
+    );
+  }
+}

lib/widgets/common/grid/selector.dart

@@ -1,8 +1,7 @@
 import 'dart:async';
 import 'dart:math';
 
-import 'package:aves/model/entry.dart';
+import 'package:aves/model/selection.dart';
-import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/utils/math_utils.dart';
 import 'package:aves/widgets/common/extensions/media_query.dart';
 import 'package:aves/widgets/common/grid/section_layout.dart';
@@ -10,9 +9,9 @@ import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:provider/provider.dart';
 
-class GridSelectionGestureDetector extends StatefulWidget {
+class GridSelectionGestureDetector<T> extends StatefulWidget {
   final bool selectable;
-  final CollectionLens collection;
+  final List<T> entries;
   final ScrollController scrollController;
   final ValueNotifier<double> appBarHeightNotifier;
   final Widget child;
@@ -20,17 +19,17 @@ class GridSelectionGestureDetector extends StatefulWidget {
   const GridSelectionGestureDetector({
     Key? key,
     this.selectable = true,
-    required this.collection,
+    required this.entries,
     required this.scrollController,
     required this.appBarHeightNotifier,
     required this.child,
   }) : super(key: key);
 
   @override
-  _GridSelectionGestureDetectorState createState() => _GridSelectionGestureDetectorState();
+  _GridSelectionGestureDetectorState createState() => _GridSelectionGestureDetectorState<T>();
 }
 
-class _GridSelectionGestureDetectorState extends State<GridSelectionGestureDetector> {
+class _GridSelectionGestureDetectorState<T> extends State<GridSelectionGestureDetector<T>> {
   bool _pressing = false, _selecting = false;
   late int _fromIndex, _lastToIndex;
   late Offset _localPosition;
@@ -38,9 +37,7 @@ class _GridSelectionGestureDetectorState extends State<GridSelectionGestureDetec
   late double _scrollSpeedFactor;
   Timer? _updateTimer;
 
-  CollectionLens get collection => widget.collection;
+  List<T> get entries => widget.entries;
-
-  List<AvesEntry> get entries => collection.sortedEntries;
 
   ScrollController get scrollController => widget.scrollController;
 
@@ -58,8 +55,9 @@ class _GridSelectionGestureDetectorState extends State<GridSelectionGestureDetec
               final fromEntry = _getEntryAt(details.localPosition);
               if (fromEntry == null) return;
 
-              collection.toggleSelection(fromEntry);
+              final selection = context.read<Selection<T>>();
-              _selecting = collection.isSelected([fromEntry]);
+              selection.toggleSelection(fromEntry);
+              _selecting = selection.isSelected([fromEntry]);
               _fromIndex = entries.indexOf(fromEntry);
               _lastToIndex = _fromIndex;
               _scrollableInsets = EdgeInsets.only(
@@ -134,41 +132,42 @@ class _GridSelectionGestureDetectorState extends State<GridSelectionGestureDetec
     }
   }
 
-  AvesEntry? _getEntryAt(Offset localPosition) {
+  T? _getEntryAt(Offset localPosition) {
     // as of Flutter v1.22.5, `hitTest` on the `ScrollView` render object works fine when it is static,
     // but when it is scrolling (through controller animation), result is incomplete and children are missing,
     // so we use custom layout computation instead to find the entry.
     final offset = Offset(0, scrollController.offset - appBarHeight) + localPosition;
-    final sectionedListLayout = context.read<SectionedListLayout<AvesEntry>>();
+    final sectionedListLayout = context.read<SectionedListLayout<T>>();
     return sectionedListLayout.getItemAt(offset);
   }
 
   void _toggleSelectionToIndex(int toIndex) {
     if (toIndex == -1) return;
 
+    final selection = context.read<Selection<T>>();
     if (_selecting) {
       if (toIndex <= _fromIndex) {
         if (toIndex < _lastToIndex) {
-          collection.addToSelection(entries.getRange(toIndex, min(_fromIndex, _lastToIndex)));
+          selection.addToSelection(entries.getRange(toIndex, min(_fromIndex, _lastToIndex)));
           if (_fromIndex < _lastToIndex) {
-            collection.removeFromSelection(entries.getRange(_fromIndex + 1, _lastToIndex + 1));
+            selection.removeFromSelection(entries.getRange(_fromIndex + 1, _lastToIndex + 1));
           }
         } else if (_lastToIndex < toIndex) {
-          collection.removeFromSelection(entries.getRange(_lastToIndex, toIndex));
+          selection.removeFromSelection(entries.getRange(_lastToIndex, toIndex));
         }
       } else if (_fromIndex < toIndex) {
         if (_lastToIndex < toIndex) {
-          collection.addToSelection(entries.getRange(max(_fromIndex, _lastToIndex), toIndex + 1));
+          selection.addToSelection(entries.getRange(max(_fromIndex, _lastToIndex), toIndex + 1));
           if (_lastToIndex < _fromIndex) {
-            collection.removeFromSelection(entries.getRange(_lastToIndex, _fromIndex));
+            selection.removeFromSelection(entries.getRange(_lastToIndex, _fromIndex));
           }
         } else if (toIndex < _lastToIndex) {
-          collection.removeFromSelection(entries.getRange(toIndex + 1, _lastToIndex + 1));
+          selection.removeFromSelection(entries.getRange(toIndex + 1, _lastToIndex + 1));
         }
       }
       _lastToIndex = toIndex;
     } else {
-      collection.removeFromSelection(entries.getRange(min(_fromIndex, toIndex), max(_fromIndex, toIndex) + 1));
+      selection.removeFromSelection(entries.getRange(min(_fromIndex, toIndex), max(_fromIndex, toIndex) + 1));
     }
   }
 }

lib/widgets/common/providers/selection_provider.dart

@@ -0,0 +1,20 @@
+import 'package:aves/model/selection.dart';
+import 'package:flutter/widgets.dart';
+import 'package:provider/provider.dart';
+
+class SelectionProvider<T> extends StatelessWidget {
+  final Widget child;
+
+  const SelectionProvider({
+    Key? key,
+    required this.child,
+  }) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return ChangeNotifierProvider<Selection<T>>(
+      create: (context) => Selection<T>(),
+      child: child,
+    );
+  }
+}

lib/widgets/dialogs/item_pick_dialog.dart

@@ -1,9 +1,11 @@
 import 'package:aves/app_mode.dart';
+import 'package:aves/model/entry.dart';
 import 'package:aves/model/source/collection_lens.dart';
 import 'package:aves/widgets/collection/collection_grid.dart';
 import 'package:aves/widgets/collection/collection_page.dart';
 import 'package:aves/widgets/common/basic/insets.dart';
 import 'package:aves/widgets/common/providers/media_query_data_provider.dart';
+import 'package:aves/widgets/common/providers/selection_provider.dart';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
 
@@ -36,7 +38,8 @@ class _ItemPickDialogState extends State<ItemPickDialog> {
       value: ValueNotifier(AppMode.pickInternal),
       child: MediaQueryDataProvider(
         child: Scaffold(
-          body: GestureAreaProtectorStack(
+          body: SelectionProvider<AvesEntry>(
+            child: GestureAreaProtectorStack(
               child: SafeArea(
                 bottom: false,
                 child: ChangeNotifierProvider<CollectionLens>.value(
@@ -49,6 +52,7 @@ class _ItemPickDialogState extends State<ItemPickDialog> {
             ),
           ),
         ),
+      ),
     );
   }
 }