Backport fix for issue where thumbnails had the wrong aspect ratio

Author: yaira2

src/Files.Uwp/ViewModels/ItemViewModel.cs

@@ -926,7 +926,7 @@ public bool IsLoadingItems
             }
         }
 
-        private async Task LoadItemThumbnail(ListedItem item, uint thumbnailSize = 20, IStorageItem matchingStorageItem = null)
+        private async Task LoadItemThumbnail(ListedItem item, uint thumbnailSize = 80, IStorageItem matchingStorageItem = null)
         {
             var wasIconLoaded = false;
             if (item.IsLibraryItem || item.PrimaryItemAttribute == StorageItemTypes.File || item.IsZipItem)
@@ -937,7 +937,7 @@ private async Task LoadItemThumbnail(ListedItem item, uint thumbnailSize = 20, I
                     var matchingStorageFile = matchingStorageItem.AsBaseStorageFile() ?? await GetFileFromPathAsync(item.ItemPath);
                     if (matchingStorageFile != null)
                     {
-                        var mode = thumbnailSize < 80 ? ThumbnailMode.ListView : ThumbnailMode.DocumentsView;
+                        var mode = thumbnailSize < 80 ? ThumbnailMode.ListView : ThumbnailMode.SingleItem;
 
                         using StorageItemThumbnail Thumbnail = await FilesystemTasks.Wrap(() => matchingStorageFile.GetThumbnailAsync(mode, thumbnailSize, ThumbnailOptions.ResizeThumbnail).AsTask());
                         if (!(Thumbnail == null || Thumbnail.Size == 0 || Thumbnail.OriginalHeight == 0 || Thumbnail.OriginalWidth == 0))
@@ -1004,7 +1004,7 @@ await dispatcherQueue.EnqueueAsync(async () =>
                     {
                         var mode = thumbnailSize < 80 ? ThumbnailMode.ListView : ThumbnailMode.SingleItem;
 
-                        using StorageItemThumbnail Thumbnail = await FilesystemTasks.Wrap(() => matchingStorageFolder.GetThumbnailAsync(mode, thumbnailSize, ThumbnailOptions.ResizeThumbnail).AsTask());
+                        using StorageItemThumbnail Thumbnail = await FilesystemTasks.Wrap(() => matchingStorageFolder.GetThumbnailAsync(mode, thumbnailSize, ThumbnailOptions.ReturnOnlyIfCached).AsTask());
                         if (!(Thumbnail == null || Thumbnail.Size == 0 || Thumbnail.OriginalHeight == 0 || Thumbnail.OriginalWidth == 0))
                         {
                             await dispatcherQueue.EnqueueAsync(async () =>