[4.27-plus] 将 UBlueprintGeneratedClasses 改为资源，以便在编辑器中查看已生成的蓝图。

Engine/Source/Runtime/AssetRegistry/Private/AssetRegistry.cpp

@@ -773,6 +773,14 @@ bool UAssetRegistryImpl::EnumerateAssets(const FARCompiledFilter& InFilter, TFun
 					return;
 				}
 
+#if WITH_EDITOR
+				// Skip classes that report themselves as assets but that the editor AssetRegistry is currently not counting as assets
+				if (ShouldSkipAsset(Obj->GetClass()->GetFName(), InMemoryPackage->GetPackageFlags()))
+				{
+					return;
+				}
+#endif
+
 				// Package name
 				const FName PackageName = InMemoryPackage->GetFName();
 
@@ -2117,9 +2125,17 @@ void UAssetRegistryImpl::AssetSearchDataGathered(const double TickStartTime, TBa
 	// Add the found assets
 	while (AssetResults.Num() > 0)
 	{
-		FAssetData*& BackgroundResult = AssetResults.Pop();
+		// Delete or take ownership of the BackgroundResult; it was originally new'd by an FPackageReader
+		TUniquePtr<FAssetData> BackgroundResult(AssetResults.Pop());
+		CA_ASSUME(BackgroundResult.Get() != nullptr);
 
-		CA_ASSUME(BackgroundResult);
+#if WITH_EDITOR
+		// Skip Assets that we filter out
+		if (ShouldSkipAsset(BackgroundResult->AssetClass, BackgroundResult->PackageFlags))
+		{
+			continue;
+		}
+#endif
 
 		// Try to update any asset data that may already exist
 		FAssetData* AssetData = State.CachedAssetsByObjectPath.FindRef(BackgroundResult->ObjectPath);
@@ -2128,20 +2144,16 @@ void UAssetRegistryImpl::AssetSearchDataGathered(const double TickStartTime, TBa
 		if (AssetData)
 		{
 			// If this ensure fires then we've somehow processed the same result more than once, and that should never happen
-			if (ensure(AssetData != BackgroundResult))
+			if (ensure(AssetData != BackgroundResult.Get()))
 			{
 				// The asset exists in the cache, update it
 				UpdateAssetData(AssetData, *BackgroundResult);
-
-				// Delete the result that was originally created by an FPackageReader
-				delete BackgroundResult;
-				BackgroundResult = nullptr;
 			}
 		}
 		else
 		{
 			// The asset isn't in the cache yet, add it and notify subscribers
-			AddAssetData(BackgroundResult);
+			AddAssetData(BackgroundResult.Release());
 		}
 
 		// Populate the path tree
@@ -2661,8 +2673,29 @@ void UAssetRegistryImpl::OnDirectoryChanged(const TArray<FFileChangeData>& FileC
 	ScanModifiedAssetFiles(ModifiedFiles);
 }
 
+bool UAssetRegistryImpl::ShouldSkipAsset(FName AssetClass, uint32 PackageFlags) const
+{
+	// We do not yet support having UBlueprintGeneratedClasses be assets when the UBlueprint is also
+	// an asset; the content browser does not handle the multiple assets correctly and displays this
+	// class asset as if it is in a separate package. Revisit when we have removed the UBlueprint as an asset
+	// or when we support multiple assets.
+	static FName NAME_BlueprintGeneratedClass = TEXT("BlueprintGeneratedClass");
+	bool bIsCooked = (PackageFlags & PKG_FilterEditorOnly) != 0;
+	if (!bIsCooked && AssetClass == NAME_BlueprintGeneratedClass)
+	{
+		return true;
+	}
+	return false;
+}
+
 void UAssetRegistryImpl::OnAssetLoaded(UObject *AssetLoaded)
 {
+	UPackage* Package = AssetLoaded->GetPackage();
+	if (Package && ShouldSkipAsset(AssetLoaded->GetClass()->GetFName(), Package->GetPackageFlags()))
+	{
+		return;
+	}
+
 	LoadedAssetsToProcess.Add(AssetLoaded);
 }
 

Engine/Source/Runtime/AssetRegistry/Private/AssetRegistry.h

@@ -213,6 +213,9 @@ class UAssetRegistryImpl : public UObject, public IAssetRegistry
 	/** Called when a file in a content directory changes on disk */
 	void OnDirectoryChanged(const TArray<struct FFileChangeData>& Files);
 
+	/** Called to check whether we should filter out assets of the given class and packageflags from the editor's AssetRegistry */
+	bool ShouldSkipAsset(FName AssetClass, uint32 PackageFlags) const;
+
 	/** Called when an asset is loaded, it will possibly update the cache */
 	void OnAssetLoaded(UObject *AssetLoaded);
 

Engine/Source/Runtime/AssetRegistry/Private/AssetRegistryState.cpp

@@ -1492,11 +1492,18 @@ void FAssetRegistryState::AddAssetData(FAssetData* AssetData)
 {
 	NumAssets++;
 
+	FAssetData*& ExistingByObjectPath = CachedAssetsByObjectPath.FindOrAdd(AssetData->ObjectPath);
+	if (ExistingByObjectPath)
+	{
+		UE_LOG(LogAssetRegistry, Error, TEXT("AddAssetData called with ObjectPath %s which already exists. ")
+			TEXT("This will overwrite and leak the existing AssetData."), *AssetData->ObjectPath.ToString());
+	}
+	ExistingByObjectPath = AssetData;
+
 	TArray<FAssetData*>& PackageAssets = CachedAssetsByPackageName.FindOrAdd(AssetData->PackageName);
 	TArray<FAssetData*>& PathAssets = CachedAssetsByPath.FindOrAdd(AssetData->PackagePath);
 	TArray<FAssetData*>& ClassAssets = CachedAssetsByClass.FindOrAdd(AssetData->AssetClass);
 
-	CachedAssetsByObjectPath.Add(AssetData->ObjectPath, AssetData);
 	PackageAssets.Add(AssetData);
 	PathAssets.Add(AssetData);
 	ClassAssets.Add(AssetData);

Engine/Source/Runtime/Engine/Classes/Engine/BlueprintGeneratedClass.h

@@ -746,6 +746,8 @@ class ENGINE_API UBlueprintGeneratedClass : public UClass
 #if WITH_EDITOR
 	virtual UClass* RegenerateClass(UClass* ClassToRegenerate, UObject* PreviousCDO) override;
 #endif	//WITH_EDITOR
+	virtual bool IsAsset() const override;
+
 	// End UObject interface
 
 	// UClass interface

Engine/Source/Runtime/Engine/Private/BlueprintGeneratedClass.cpp

@@ -162,8 +162,11 @@ void UBlueprintGeneratedClass::PostLoad()
 FPrimaryAssetId UBlueprintGeneratedClass::GetPrimaryAssetId() const
 {
 	FPrimaryAssetId AssetId;
-	if (!ensure(ClassDefaultObject))
+	if (!ClassDefaultObject)
 	{
+		// All UBlueprintGeneratedClass objects should have a pointer to their generated ClassDefaultObject, except for the
+		// CDO itself of the UBlueprintGeneratedClass class.
+		verify(HasAnyFlags(RF_ClassDefaultObject));
 		return AssetId;
 	}
 
@@ -1583,6 +1586,14 @@ UClass* UBlueprintGeneratedClass::RegenerateClass(UClass* ClassToRegenerate, UOb
 }
 #endif
 
+bool UBlueprintGeneratedClass::IsAsset() const
+{
+	// UClass::IsAsset returns false; override that to return true for BlueprintGeneratedClasses,
+	// but only if the instance satisfies the regular definition of an asset (RF_Public, not transient, etc)
+	// and only if it is the active BPGC matching the Blueprint
+	return UObject::IsAsset() && !HasAnyClassFlags(CLASS_NewerVersionExists);
+}
+
 void UBlueprintGeneratedClass::Link(FArchive& Ar, bool bRelinkExistingProperties)
 {
 	Super::Link(Ar, bRelinkExistingProperties);