From 6dd72cdf32a252f94d337b0593caf91f987f4dd2 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Mon, 11 Dec 2023 14:14:55 +0100
Subject: [PATCH] Add removing thumbnails for deleted assets

#1729
---
 Source/Editor/Content/PreviewsCache.cpp       | 19 ++++++++++++------
 .../Content/Thumbnails/ThumbnailsModule.cs    | 20 ++-----------------
 2 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/Source/Editor/Content/PreviewsCache.cpp b/Source/Editor/Content/PreviewsCache.cpp
index 2d62e8170..b0f3619a5 100644
--- a/Source/Editor/Content/PreviewsCache.cpp
+++ b/Source/Editor/Content/PreviewsCache.cpp
@@ -5,6 +5,7 @@
 #include "Engine/Graphics/GPUContext.h"
 #include "Engine/Threading/Threading.h"
 #include "Engine/Graphics/RenderTools.h"
+#include "Engine/Content/Content.h"
 #include "Engine/Content/Factories/BinaryAssetFactory.h"
 #include "Engine/ContentImporters/AssetsImportingManager.h"
 #include "Engine/Content/Upgraders/TextureAssetUpgrader.h"
@@ -92,15 +93,12 @@ SpriteHandle PreviewsCache::FindSlot(const Guid& id)
 {
     if (WaitForLoaded())
         return SpriteHandle::Invalid;
-
-    // Find entry
     int32 index;
     if (_assets.Find(id, index))
     {
         const String spriteName = StringUtils::ToString(index);
         return FindSprite(spriteName);
     }
-
     return SpriteHandle::Invalid;
 }
 
@@ -114,6 +112,17 @@ Asset::LoadResult PreviewsCache::load()
         return LoadResult::Failed;
     _assets.Set(previewsMetaChunk->Get<Guid>(), ASSETS_ICONS_PER_ATLAS);
 
+    // Verify if cached assets still exist (don't store thumbnails for removed files)
+    AssetInfo assetInfo;
+    for (Guid& id : _assets)
+    {
+        if (id.IsValid() && Content::GetAsset(id) == nullptr && !Content::GetAssetInfo(id, assetInfo))
+        {
+            // Free slot (no matter the texture contents)
+            id = Guid::Empty;
+        }
+    }
+
     // Setup atlas sprites array
     Sprite sprite;
     sprite.Area.Size = static_cast<float>(ASSET_ICON_SIZE) / ASSETS_ICONS_ATLAS_SIZE;
@@ -162,7 +171,7 @@ SpriteHandle PreviewsCache::OccupySlot(GPUTexture* source, const Guid& id)
     if (WaitForLoaded())
         return SpriteHandle::Invalid;
 
-    // Find free slot and for that asset
+    // Find this asset slot or use the first empty
     int32 index = _assets.Find(id);
     if (index == INVALID_INDEX)
         index = _assets.Find(Guid::Empty);
@@ -201,14 +210,12 @@ bool PreviewsCache::ReleaseSlot(const Guid& id)
 {
     bool result = false;
     ScopeLock lock(Locker);
-
     int32 index = _assets.Find(id);
     if (index != INVALID_INDEX)
     {
         _assets[index] = Guid::Empty;
         result = true;
     }
-
     return result;
 }
 
diff --git a/Source/Editor/Content/Thumbnails/ThumbnailsModule.cs b/Source/Editor/Content/Thumbnails/ThumbnailsModule.cs
index 1282e4daa..2b830c933 100644
--- a/Source/Editor/Content/Thumbnails/ThumbnailsModule.cs
+++ b/Source/Editor/Content/Thumbnails/ThumbnailsModule.cs
@@ -21,15 +21,11 @@ namespace FlaxEditor.Content.Thumbnails
         /// </summary>
         public const float MinimumRequiredResourcesQuality = 0.8f;
 
-        // TODO: free atlas slots for deleted assets
-
         private readonly List<PreviewsCache> _cache = new List<PreviewsCache>(4);
         private readonly string _cacheFolder;
-
-        private DateTime _lastFlushTime;
-
         private readonly List<ThumbnailRequest> _requests = new List<ThumbnailRequest>(128);
         private readonly PreviewRoot _guiRoot = new PreviewRoot();
+        private DateTime _lastFlushTime;
         private RenderTask _task;
         private GPUTexture _output;
 
@@ -88,7 +84,6 @@ namespace FlaxEditor.Content.Thumbnails
                         }
                     }
 
-                    // Add request
                     AddRequest(assetItem, proxy);
                 }
             }
@@ -118,9 +113,7 @@ namespace FlaxEditor.Content.Thumbnails
                 for (int i = 0; i < _cache.Count; i++)
                 {
                     if (_cache[i].ReleaseSlot(assetItem.ID))
-                    {
                         break;
-                    }
                 }
             }
         }
@@ -198,13 +191,7 @@ namespace FlaxEditor.Content.Thumbnails
         /// <inheritdoc />
         void IContentItemOwner.OnItemDeleted(ContentItem item)
         {
-            if (item is AssetItem assetItem)
-            {
-                lock (_requests)
-                {
-                    RemoveRequest(assetItem);
-                }
-            }
+            DeletePreview(item);
         }
 
         /// <inheritdoc />
@@ -494,10 +481,7 @@ namespace FlaxEditor.Content.Thumbnails
         {
             // Wait some frames before start generating previews (late init feature)
             if (Time.TimeSinceStartup < 1.0f || HasAllAtlasesLoaded() == false)
-            {
-                // Back
                 return;
-            }
 
             lock (_requests)
             {