fix: persist search page scroll offset between rebuilds (#22733)

fix: persist search scroll between rebuilds

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>
Co-authored-by: Alex <alex.tran1502@gmail.com>

mobile/lib/domain/models/search_result.model.dart

@@ -3,27 +3,30 @@ import 'package:immich_mobile/domain/models/asset/base_asset.model.dart';
 
 class SearchResult {
   final List<BaseAsset> assets;
+  final double scrollOffset;
   final int? nextPage;
 
-  const SearchResult({required this.assets, this.nextPage});
+  const SearchResult({required this.assets, this.scrollOffset = 0.0, this.nextPage});
 
-  int get totalAssets => assets.length;
-
-  SearchResult copyWith({List<BaseAsset>? assets, int? nextPage}) {
-    return SearchResult(assets: assets ?? this.assets, nextPage: nextPage ?? this.nextPage);
+  SearchResult copyWith({List<BaseAsset>? assets, int? nextPage, double? scrollOffset}) {
+    return SearchResult(
+      assets: assets ?? this.assets,
+      nextPage: nextPage ?? this.nextPage,
+      scrollOffset: scrollOffset ?? this.scrollOffset,
+    );
   }
 
   @override
-  String toString() => 'SearchResult(assets: $assets, nextPage: $nextPage)';
+  String toString() => 'SearchResult(assets: ${assets.length}, nextPage: $nextPage, scrollOffset: $scrollOffset)';
 
   @override
   bool operator ==(covariant SearchResult other) {
     if (identical(this, other)) return true;
     final listEquals = const DeepCollectionEquality().equals;
 
-    return listEquals(other.assets, assets) && other.nextPage == nextPage;
+    return listEquals(other.assets, assets) && other.nextPage == nextPage && other.scrollOffset == scrollOffset;
   }
 
   @override
-  int get hashCode => assets.hashCode ^ nextPage.hashCode;
+  int get hashCode => assets.hashCode ^ nextPage.hashCode ^ scrollOffset.hashCode;
 }

mobile/lib/domain/services/timeline.service.dart

@@ -203,7 +203,7 @@ class TimelineService {
   Future<void> dispose() async {
     await _bucketSubscription?.cancel();
     _bucketSubscription = null;
-    _buffer.clear();
+    _buffer = [];
     _bufferOffset = 0;
   }
 }

mobile/lib/presentation/pages/search/drift_search.page.dart

@@ -599,9 +599,9 @@ class _SearchResultGrid extends ConsumerWidget {
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    final searchResult = ref.watch(paginatedSearchProvider);
+    final assets = ref.watch(paginatedSearchProvider.select((s) => s.assets));
 
-    if (searchResult.totalAssets == 0) {
+    if (assets.isEmpty) {
       return const _SearchEmptyContent();
     }
 
@@ -615,6 +615,7 @@ class _SearchResultGrid extends ConsumerWidget {
 
         if (metrics.pixels >= metrics.maxScrollExtent && isVerticalScroll && !isBottomSheetNotification) {
           onScrollEnd();
+          ref.read(paginatedSearchProvider.notifier).setScrollOffset(metrics.maxScrollExtent);
         }
 
         return true;
@@ -623,17 +624,18 @@ class _SearchResultGrid extends ConsumerWidget {
         child: ProviderScope(
           overrides: [
             timelineServiceProvider.overrideWith((ref) {
-              final timelineService = ref.watch(timelineFactoryProvider).fromAssets(searchResult.assets);
+              final timelineService = ref.watch(timelineFactoryProvider).fromAssets(assets);
               ref.onDispose(timelineService.dispose);
               return timelineService;
             }),
           ],
           child: Timeline(
-            key: ValueKey(searchResult.totalAssets),
+            key: ValueKey(assets.length),
             groupBy: GroupAssetsBy.none,
             appBar: null,
             bottomSheet: const GeneralBottomSheet(minChildSize: 0.20),
             snapToMonth: false,
+            initialScrollOffset: ref.read(paginatedSearchProvider.select((s) => s.scrollOffset)),
           ),
         ),
       ),

mobile/lib/presentation/pages/search/paginated_search.provider.dart

@@ -24,12 +24,20 @@ class PaginatedSearchNotifier extends StateNotifier<SearchResult> {
       return false;
     }
 
-    state = SearchResult(assets: [...state.assets, ...result.assets], nextPage: result.nextPage);
+    state = SearchResult(
+      assets: [...state.assets, ...result.assets],
+      nextPage: result.nextPage,
+      scrollOffset: state.scrollOffset,
+    );
 
     return true;
   }
 
+  void setScrollOffset(double offset) {
+    state = state.copyWith(scrollOffset: offset);
+  }
+
   clear() {
-    state = const SearchResult(assets: [], nextPage: 1);
+    state = const SearchResult(assets: [], nextPage: 1, scrollOffset: 0.0);
   }
 }

mobile/lib/presentation/widgets/timeline/timeline.widget.dart

@@ -40,6 +40,7 @@ class Timeline extends StatelessWidget {
     this.groupBy,
     this.withScrubber = true,
     this.snapToMonth = true,
+    this.initialScrollOffset,
   });
 
   final Widget? topSliverWidget;
@@ -51,6 +52,7 @@ class Timeline extends StatelessWidget {
   final GroupAssetsBy? groupBy;
   final bool withScrubber;
   final bool snapToMonth;
+  final double? initialScrollOffset;
 
   @override
   Widget build(BuildContext context) {
@@ -78,6 +80,7 @@ class Timeline extends StatelessWidget {
             bottomSheet: bottomSheet,
             withScrubber: withScrubber,
             snapToMonth: snapToMonth,
+            initialScrollOffset: initialScrollOffset,
           ),
         ),
       ),
@@ -93,6 +96,7 @@ class _SliverTimeline extends ConsumerStatefulWidget {
     this.bottomSheet,
     this.withScrubber = true,
     this.snapToMonth = true,
+    this.initialScrollOffset,
   });
 
   final Widget? topSliverWidget;
@@ -101,6 +105,7 @@ class _SliverTimeline extends ConsumerStatefulWidget {
   final Widget? bottomSheet;
   final bool withScrubber;
   final bool snapToMonth;
+  final double? initialScrollOffset;
 
   @override
   ConsumerState createState() => _SliverTimelineState();
@@ -124,7 +129,10 @@ class _SliverTimelineState extends ConsumerState<_SliverTimeline> {
   @override
   void initState() {
     super.initState();
-    _scrollController = ScrollController(onAttach: _restoreScalePosition);
+    _scrollController = ScrollController(
+      initialScrollOffset: widget.initialScrollOffset ?? 0.0,
+      onAttach: _restoreScalePosition,
+    );
     _eventSubscription = EventStream.shared.listen(_onEvent);
 
     final currentTilesPerRow = ref.read(settingsProvider).get(Setting.tilesPerRow);