SlateDrawBuffer.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "UObject/GCObject.h"
#include "HAL/CriticalSection.h"
#include "Types/SlateVector2.h"
#include "Tasks/Task.h"
 
#include <atomic>
 
class FSlateWindowElementList;
class SWindow;
 
class FSlateDrawBuffer : public FGCObject
{
public:
    SLATECORE_API FSlateDrawBuffer();
    SLATECORE_API ~FSlateDrawBuffer();
 
    SLATECORE_API void ClearBuffer();
 
    SLATECORE_API void UpdateResourceVersion(uint32 NewResourceVersion);
 
    SLATECORE_API FSlateWindowElementList& AddWindowElementList(TSharedRef<SWindow> ForWindow);
 
    SLATECORE_API void RemoveUnusedWindowElement(const TArray<SWindow*>& AllWindows);
 
    const TArray< TSharedRef<FSlateWindowElementList> >& GetWindowElementLists()
    {
        return WindowElementLists;
    }
 
    SLATECORE_API bool Lock();
 
    SLATECORE_API void Unlock(const UE::Tasks::FTask& PrerequisiteTask);
 
    void Unlock()
    {
        Unlock(UE::Tasks::FTask{});
    }
 
    bool IsLocked() const
    {
        return bIsLocked;
    }
 
    SLATECORE_API virtual void AddReferencedObjects(FReferenceCollector& Collector) override;
    virtual FString GetReferencerName() const
    {
        return TEXT("FSlateDrawBuffer for Uncached Elements");
    }
 
private:
    // List of window element lists
    TArray< TSharedRef<FSlateWindowElementList> > WindowElementLists;
 
    // List of window element lists that we store from the previous frame 
    // that we restore if they're requested again.
    TArray< TSharedRef<FSlateWindowElementList> > WindowElementListsPool;
 
    FCriticalSection GCLock;
    std::atomic<bool> bIsLocked;
    bool bIsLockedBySlateThread;
 
    // Last recorded version from the render. The WindowElementListsPool is emptied when this changes.
    uint32 ResourceVersion;
 
public:
    FDeprecateSlateVector2D ViewOffset;
};