Show fav icon for only favorite album

lib/ui/collections/collection_item_widget.dart

@@ -27,22 +27,27 @@ class CollectionItem extends StatelessWidget {
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: <Widget>[
-          ClipRRect(
-            borderRadius: BorderRadius.circular(4),
-            child: SizedBox(
-              height: sideOfThumbnail,
-              width: sideOfThumbnail,
-              child: Hero(
-                tag: heroTag,
-                child: c.thumbnail != null
-                    ? ThumbnailWidget(
-                        c.thumbnail,
-                        shouldShowArchiveStatus: c.collection.isArchived(),
-                        key: Key(heroTag),
-                      )
-                    : const NoThumbnailWidget(),
+          Stack(
+            children: [
+              ClipRRect(
+                borderRadius: BorderRadius.circular(4),
+                child: SizedBox(
+                  height: sideOfThumbnail,
+                  width: sideOfThumbnail,
+                  child: Hero(
+                    tag: heroTag,
+                    child: c.thumbnail != null
+                        ? ThumbnailWidget(
+                            c.thumbnail,
+                            shouldShowArchiveStatus: c.collection.isArchived(),
+                            showFavForAlbumOnly: true,
+                            key: Key(heroTag),
+                          )
+                        : const NoThumbnailWidget(),
+                  ),
+                ),
               ),
-            ),
+            ],
           ),
           Column(
             crossAxisAlignment: CrossAxisAlignment.start,

lib/ui/create_collection_page.dart

@@ -161,7 +161,10 @@ class _CreateCollectionPageState extends State<CreateCollectionPage> {
                 width: 64,
                 key: Key("collection_item:" + (item.thumbnail?.tag ?? "")),
                 child: item.thumbnail != null
-                    ? ThumbnailWidget(item.thumbnail)
+                    ? ThumbnailWidget(
+                        item.thumbnail,
+                        showFavForAlbumOnly: true,
+                      )
                     : const NoThumbnailWidget(),
               ),
             ),

lib/ui/viewer/file/thumbnail_widget.dart

@@ -13,6 +13,7 @@ import 'package:photos/events/local_photos_updated_event.dart';
 import 'package:photos/models/file.dart';
 import 'package:photos/models/file_type.dart';
 import 'package:photos/models/trash_file.dart';
+import 'package:photos/services/favorites_service.dart';
 import 'package:photos/ui/viewer/file/file_icons_widget.dart';
 import 'package:photos/utils/file_util.dart';
 import 'package:photos/utils/thumbnail_util.dart';
@@ -22,6 +23,7 @@ class ThumbnailWidget extends StatefulWidget {
   final BoxFit fit;
   final bool shouldShowSyncStatus;
   final bool shouldShowArchiveStatus;
+  final bool showFavForAlbumOnly;
   final bool shouldShowLivePhotoOverlay;
   final Duration diskLoadDeferDuration;
   final Duration serverLoadDeferDuration;
@@ -33,6 +35,7 @@ class ThumbnailWidget extends StatefulWidget {
     this.shouldShowSyncStatus = true,
     this.shouldShowLivePhotoOverlay = false,
     this.shouldShowArchiveStatus = false,
+    this.showFavForAlbumOnly = false,
     this.diskLoadDeferDuration,
     this.serverLoadDeferDuration,
   }) : super(key: key ?? Key(file.tag));
@@ -94,6 +97,12 @@ class _ThumbnailWidgetState extends State<ThumbnailWidget> {
     Widget content;
     if (image != null) {
       final List<Widget> contentChildren = [image];
+      if (FavoritesService.instance.isFavoriteCache(
+        widget.file,
+        checkOnlyAlbum: widget.showFavForAlbumOnly,
+      )) {
+        contentChildren.add(const FavoriteOverlayIcon());
+      }
       if (widget.file.fileType == FileType.video) {
         contentChildren.add(const VideoOverlayIcon());
       } else if (widget.file.fileType == FileType.livePhoto &&