Fixed cached resource handles getting invalid after reloading texture resources.

CHANGES.md

@@ -8,6 +8,7 @@ Change History
 Version: 1.22 (2021/04)
 - Fixed potential for initialization fiasco when using delegates container.
 - Fixed bug in code protecting redirecting handles from self-referencing.
+- Fixed cached resource handles getting invalid after reloading texture resources.
 
 Version: 1.21 (2020/07-09)
 Improving stability

Source/ImGui/Private/TextureManager.cpp

@@ -125,7 +125,7 @@ FTextureManager::FTextureEntry::FTextureEntry(const FName& InName, UTexture2D* I
 
 	// Create brush and resource handle for input texture.
 	Brush.SetResourceObject(InTexture);
-	ResourceHandle = FSlateApplication::Get().GetRenderer()->GetResourceHandle(Brush);
+	CachedResourceHandle = FSlateApplication::Get().GetRenderer()->GetResourceHandle(Brush);
 }
 
 FTextureManager::FTextureEntry::~FTextureEntry()
@@ -142,7 +142,7 @@ FTextureManager::FTextureEntry& FTextureManager::FTextureEntry::operator=(FTextu
 	Name = MoveTemp(Other.Name);
 	Texture = MoveTemp(Other.Texture);
 	Brush = MoveTemp(Other.Brush);
-	ResourceHandle = MoveTemp(Other.ResourceHandle);
+	CachedResourceHandle = MoveTemp(Other.CachedResourceHandle);
 
 	// Reset the other entry (without releasing resources which are already moved to this instance) to remove tracks
 	// of ownership and mark it as empty/reusable.
@@ -151,6 +151,15 @@ FTextureManager::FTextureEntry& FTextureManager::FTextureEntry::operator=(FTextu
 	return *this;
 }
 
+const FSlateResourceHandle& FTextureManager::FTextureEntry::GetResourceHandle() const
+{
+	if (!CachedResourceHandle.IsValid() && Brush.HasUObject())
+	{
+		CachedResourceHandle = FSlateApplication::Get().GetRenderer()->GetResourceHandle(Brush);
+	}
+	return CachedResourceHandle;
+}
+
 void FTextureManager::FTextureEntry::Reset(bool bReleaseResources)
 {
 	if (bReleaseResources)
@@ -175,5 +184,5 @@ void FTextureManager::FTextureEntry::Reset(bool bReleaseResources)
 	// Clean fields to make sure that we don't reference released or moved resources.
 	Texture.Reset();
 	Brush = FSlateNoResource();
-	ResourceHandle = FSlateResourceHandle();
+	CachedResourceHandle = FSlateResourceHandle();
 }

Source/ImGui/Private/TextureManager.h

@@ -41,7 +41,7 @@ public:
 	// @returns The index of a texture with given name or INDEX_NONE if there is no such texture
 	TextureIndex FindTextureIndex(const FName& Name) const
 	{
-		return TextureResources.IndexOfByPredicate([&](const auto& Entry) { return Entry.Name == Name; });
+		return TextureResources.IndexOfByPredicate([&](const auto& Entry) { return Entry.GetName() == Name; });
 	}
 
 	// Get the name of a texture at given index. Returns NAME_None, if index is out of range.
@@ -49,7 +49,7 @@ public:
 	// @returns The name of a texture at given index or NAME_None if index is out of range.
 	FName GetTextureName(TextureIndex Index) const
 	{
-		return IsInRange(Index) ? TextureResources[Index].Name : NAME_None;
+		return IsInRange(Index) ? TextureResources[Index].GetName() : NAME_None;
 	}
 
 	// Get the Slate Resource Handle to a texture at given index. If index is out of range or resources are not valid
@@ -59,7 +59,7 @@ public:
 	// found at given index
 	const FSlateResourceHandle& GetTextureHandle(TextureIndex Index) const
 	{
-		return IsValidTexture(Index) ? TextureResources[Index].ResourceHandle : ErrorTexture.ResourceHandle;
+		return IsValidTexture(Index) ? TextureResources[Index].GetResourceHandle() : ErrorTexture.GetResourceHandle();
 	}
 
 	// Create a texture from raw data.
@@ -118,7 +118,7 @@ private:
 	// Check whether index is in range and whether texture resources are valid (using NAME_None sentinel).
 	FORCEINLINE bool IsValidTexture(TextureIndex Index) const
 	{
-		return IsInRange(Index) && TextureResources[Index].Name != NAME_None;
+		return IsInRange(Index) && TextureResources[Index].GetName() != NAME_None;
 	}
 
 	// Entry for texture resources. Only supports explicit construction.
@@ -137,14 +137,17 @@ private:
 		// ... but we need move assignment to support reusing entries.
 		FTextureEntry& operator=(FTextureEntry&& Other);
 
-		FName Name = NAME_None;
+		const FName& GetName() const { return Name; }
-		TWeakObjectPtr<UTexture2D> Texture;
+		const FSlateResourceHandle& GetResourceHandle() const;
-		FSlateBrush Brush;
-		FSlateResourceHandle ResourceHandle;
 
 	private:
 
 		void Reset(bool bReleaseResources);
+
+		FName Name = NAME_None;
+		mutable FSlateResourceHandle CachedResourceHandle;
+		TWeakObjectPtr<UTexture2D> Texture;
+		FSlateBrush Brush;
 	};
 
 	TArray<FTextureEntry> TextureResources;