From b50b587a63808972c444f50e98ee480a348d30b9 Mon Sep 17 00:00:00 2001
From: Stefan Markovic <57057282+stefansjfw@users.noreply.github.com>
Date: Tue, 30 May 2023 16:58:56 +0200
Subject: [PATCH] [Peek] Fix race condition when setting preview (#26478)

---
 .../MediaPreviewer/ImagePreviewer.cs          | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/modules/peek/Peek.FilePreviewer/Previewers/MediaPreviewer/ImagePreviewer.cs b/src/modules/peek/Peek.FilePreviewer/Previewers/MediaPreviewer/ImagePreviewer.cs
index 718d823566..f02f703c04 100644
--- a/src/modules/peek/Peek.FilePreviewer/Previewers/MediaPreviewer/ImagePreviewer.cs
+++ b/src/modules/peek/Peek.FilePreviewer/Previewers/MediaPreviewer/ImagePreviewer.cs
@@ -62,8 +62,12 @@ namespace Peek.FilePreviewer.Previewers
 
         private IntPtr lowQualityThumbnail;
 
+        private ImageSource? lowQualityThumbnailPreview;
+
         private IntPtr highQualityThumbnail;
 
+        private ImageSource? highQualityThumbnailPreview;
+
         public static bool IsFileTypeSupported(string fileExt)
         {
             return _supportedFileTypes.Contains(fileExt);
@@ -110,6 +114,19 @@ namespace Peek.FilePreviewer.Previewers
 
             await Task.WhenAll(LowQualityThumbnailTask, HighQualityThumbnailTask, FullQualityImageTask);
 
+            // If Preview is still null, FullQualityImage was not available. Preview the thumbnail instead.
+            if (Preview == null)
+            {
+                if (highQualityThumbnailPreview != null)
+                {
+                    Preview = highQualityThumbnailPreview;
+                }
+                else
+                {
+                    Preview = lowQualityThumbnailPreview;
+                }
+            }
+
             if (Preview == null && HasFailedLoadingPreview())
             {
                 State = PreviewState.Error;
@@ -179,7 +196,7 @@ namespace Peek.FilePreviewer.Previewers
                     if (!IsFullImageLoaded && !IsHighQualityThumbnailLoaded)
                     {
                         var thumbnailBitmap = await BitmapHelper.GetBitmapFromHBitmapAsync(lowQualityThumbnail, IsPng(Item), cancellationToken);
-                        Preview = thumbnailBitmap;
+                        lowQualityThumbnailPreview = thumbnailBitmap;
                     }
                 });
             });
@@ -206,7 +223,7 @@ namespace Peek.FilePreviewer.Previewers
                     if (!IsFullImageLoaded)
                     {
                         var thumbnailBitmap = await BitmapHelper.GetBitmapFromHBitmapAsync(highQualityThumbnail, IsPng(Item), cancellationToken);
-                        Preview = thumbnailBitmap;
+                        highQualityThumbnailPreview = thumbnailBitmap;
                     }
                 });
             });
@@ -270,6 +287,8 @@ namespace Peek.FilePreviewer.Previewers
 
         private void Clear()
         {
+            lowQualityThumbnailPreview = null;
+            highQualityThumbnailPreview = null;
             Preview = null;
 
             if (lowQualityThumbnail != IntPtr.Zero)