WebImageCache.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Containers/UnrealString.h"
#include "WebImage.h"
 
struct FSlateBrush;
 
class FWebImageCache
{
public:
    IMAGEDOWNLOAD_API FWebImageCache();
 
    IMAGEDOWNLOAD_API void PreUnload();
 
    IMAGEDOWNLOAD_API void Empty();
 
    IMAGEDOWNLOAD_API TSharedRef<const FWebImage> Download(const FString& Url, const TOptional<FString>& DefaultImageUrl = TOptional<FString>());
 
    inline void SetDefaultStandInBrush(TAttribute<const FSlateBrush*> StandInBrushIn) { DefaultStandInBrush = StandInBrushIn; }
 
    /* This function causes the web image cache to stop holding on to strong references to images. Normally
     * once downloaded, an image is cached forever. This allows us to release images that are not currently
     * being displayed (those would have Strong pointers existing external to this class) to be released.
     */
    IMAGEDOWNLOAD_API void RelinquishUnusedImages();
 
private:
    TMap<FString, TWeakPtr<FWebImage> > UrlToImageMap;
    
    TArray< TSharedRef<FWebImage> > StrongRefCache;
 
    TAttribute< const FSlateBrush* > DefaultStandInBrush;
};