#1174 custom placeholder handling for collection-viewer hero

lib/widgets/aves_app.dart

@@ -32,6 +32,7 @@ import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/common/providers/durations_provider.dart';
 import 'package:aves/widgets/common/providers/highlight_info_provider.dart';
 import 'package:aves/widgets/common/providers/media_query_data_provider.dart';
+import 'package:aves/widgets/common/providers/viewer_entry_provider.dart';
 import 'package:aves/widgets/home_page.dart';
 import 'package:aves/widgets/navigation/tv_page_transitions.dart';
 import 'package:aves/widgets/navigation/tv_rail.dart';
@@ -224,6 +225,7 @@ class _AvesAppState extends State<AvesApp> with WidgetsBindingObserver {
         Provider<TvRailController>.value(value: _tvRailController),
         DurationsProvider(),
         HighlightInfoProvider(),
+        ViewerEntryProvider(),
       ],
       child: NotificationListener<PopExitNotification>(
         onNotification: (notification) {

lib/widgets/collection/collection_grid.dart

@@ -40,6 +40,7 @@ import 'package:aves/widgets/common/identity/buttons/outlined_button.dart';
 import 'package:aves/widgets/common/identity/empty.dart';
 import 'package:aves/widgets/common/identity/scroll_thumb.dart';
 import 'package:aves/widgets/common/providers/tile_extent_controller_provider.dart';
+import 'package:aves/widgets/common/providers/viewer_entry_provider.dart';
 import 'package:aves/widgets/common/thumbnail/decorated.dart';
 import 'package:aves/widgets/common/thumbnail/image.dart';
 import 'package:aves/widgets/common/thumbnail/notifications.dart';
@@ -49,6 +50,7 @@ import 'package:aves/widgets/viewer/entry_viewer_page.dart';
 import 'package:aves_model/aves_model.dart';
 import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:flutter_staggered_animations/flutter_staggered_animations.dart';
 import 'package:intl/intl.dart';
 import 'package:permission_handler/permission_handler.dart';
@@ -116,6 +118,12 @@ class _CollectionGridContentState extends State<_CollectionGridContent> {
   final ValueNotifier<bool> _isScrollingNotifier = ValueNotifier(false);
   final ValueNotifier<AppMode> _selectingAppModeNotifier = ValueNotifier(AppMode.pickFilteredMediaInternal);
 
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) => context.read<ViewerEntryNotifier>().value = null);
+  }
+
   @override
   void dispose() {
     _focusedItemNotifier.dispose();
@@ -238,9 +246,12 @@ class _CollectionGridContentState extends State<_CollectionGridContent> {
     );
   }
 
-  void _goToViewer(CollectionLens collection, AvesEntry entry) {
+  Future<void> _goToViewer(CollectionLens collection, AvesEntry entry) async {
+    // track viewer entry for dynamic hero placeholder
+    WidgetsBinding.instance.addPostFrameCallback((_) => context.read<ViewerEntryNotifier>().value = entry);
+
     final selection = context.read<Selection<AvesEntry>>();
-    Navigator.maybeOf(context)?.push(
+    await Navigator.maybeOf(context)?.push(
       TransparentMaterialPageRoute(
         settings: const RouteSettings(name: EntryViewerPage.routeName),
         pageBuilder: (context, a, sa) {
@@ -266,6 +277,14 @@ class _CollectionGridContentState extends State<_CollectionGridContent> {
         },
       ),
     );
+
+    // reset track viewer entry
+    final animate = context.read<Settings>().animate;
+    if (animate) {
+      // TODO TLAD fix timing when transition is incomplete, e.g. when going back while going to the viewer
+      await Future.delayed(ADurations.pageTransitionExact * timeDilation);
+    }
+    context.read<ViewerEntryNotifier>().value = null;
   }
 }
 

lib/widgets/collection/grid/tile.dart

@@ -6,6 +6,7 @@ import 'package:aves/services/intent_service.dart';
 import 'package:aves/widgets/collection/grid/list_details.dart';
 import 'package:aves/widgets/collection/grid/list_details_theme.dart';
 import 'package:aves/widgets/common/grid/scaling.dart';
+import 'package:aves/widgets/common/providers/viewer_entry_provider.dart';
 import 'package:aves/widgets/common/thumbnail/decorated.dart';
 import 'package:aves/widgets/common/thumbnail/notifications.dart';
 import 'package:aves/widgets/viewer/hero.dart';
@@ -124,5 +125,20 @@ class Tile extends StatelessWidget {
         selectable: selectable,
         highlightable: highlightable,
         heroTagger: heroTagger,
+        // do not use a hero placeholder but hide the thumbnail matching the viewer entry,
+        // so that it can hero out on an entry and come back with a hero to a different entry
+        heroPlaceholderBuilder: (context, heroSize, child) => child,
+        imageDecorator: (context, child) {
+          return Selector<ViewerEntryNotifier, bool>(
+            selector: (context, v) => v.value == entry,
+            builder: (context, isViewerEntry, child) {
+              return Visibility.maintain(
+                visible: !isViewerEntry,
+                child: child!,
+              );
+            },
+            child: child,
+          );
+        },
       );
 }

lib/widgets/common/providers/viewer_entry_provider.dart

@@ -0,0 +1,17 @@
+import 'package:aves/model/entry/entry.dart';
+import 'package:flutter/widgets.dart';
+import 'package:provider/provider.dart';
+
+class ViewerEntryProvider extends ListenableProvider<ViewerEntryNotifier> {
+  ViewerEntryProvider({
+    super.key,
+    super.child,
+  }) : super(
+          create: (context) => ViewerEntryNotifier(null),
+          dispose: (context, value) => value.dispose(),
+        );
+}
+
+class ViewerEntryNotifier extends ValueNotifier<AvesEntry?> {
+  ViewerEntryNotifier(super.value);
+}

lib/widgets/common/thumbnail/decorated.dart

@@ -13,6 +13,8 @@ class DecoratedThumbnail extends StatelessWidget {
   final ValueNotifier<bool>? cancellableNotifier;
   final bool isMosaic, selectable, highlightable;
   final Object? Function()? heroTagger;
+  final HeroPlaceholderBuilder? heroPlaceholderBuilder;
+  final TransitionBuilder? imageDecorator;
 
   static Color borderColor(BuildContext context) => Theme.of(context).dividerColor;
 
@@ -27,6 +29,8 @@ class DecoratedThumbnail extends StatelessWidget {
     this.selectable = true,
     this.highlightable = true,
     this.heroTagger,
+    this.heroPlaceholderBuilder,
+    this.imageDecorator,
   });
 
   @override
@@ -50,12 +54,13 @@ class DecoratedThumbnail extends StatelessWidget {
       isMosaic: isMosaic,
       cancellableNotifier: cancellableNotifier,
       heroTag: heroTagger?.call(),
+      heroPlaceholderBuilder: heroPlaceholderBuilder,
     );
 
     child = Stack(
       fit: StackFit.passthrough,
       children: [
-        child,
+        imageDecorator?.call(context, child) ?? child,
         ThumbnailEntryOverlay(entry: entry),
         if (selectable) ...[
           GridItemSelectionOverlay<AvesEntry>(

lib/widgets/common/thumbnail/image.dart

@@ -25,6 +25,7 @@ class ThumbnailImage extends StatefulWidget {
   final bool showLoadingBackground;
   final ValueNotifier<bool>? cancellableNotifier;
   final Object? heroTag;
+  final HeroPlaceholderBuilder? heroPlaceholderBuilder;
 
   const ThumbnailImage({
     super.key,
@@ -37,6 +38,7 @@ class ThumbnailImage extends StatefulWidget {
     this.showLoadingBackground = true,
     this.cancellableNotifier,
     this.heroTag,
+    this.heroPlaceholderBuilder,
   });
 
   @override
@@ -283,6 +285,7 @@ class _ThumbnailImageState extends State<ThumbnailImage> {
           }
           return child;
         },
+        placeholderBuilder: widget.heroPlaceholderBuilder,
         transitionOnUserGestures: true,
         child: image,
       );

lib/widgets/viewer/entry_viewer_stack.dart

@@ -18,6 +18,7 @@ import 'package:aves/widgets/aves_app.dart';
 import 'package:aves/widgets/collection/collection_page.dart';
 import 'package:aves/widgets/common/action_mixins/feedback.dart';
 import 'package:aves/widgets/common/basic/insets.dart';
+import 'package:aves/widgets/common/providers/viewer_entry_provider.dart';
 import 'package:aves/widgets/viewer/action/video_action_delegate.dart';
 import 'package:aves/widgets/viewer/controls/controller.dart';
 import 'package:aves/widgets/viewer/controls/notifications.dart';
@@ -900,6 +901,7 @@ class _EntryViewerStackState extends State<EntryViewerStack> with EntryViewContr
             predicate: (v) => v < 1,
             animate: false,
           );
+      context.read<ViewerEntryNotifier>().value = entry;
     }
   }