ImageDownloadSubsystem.h

// Copyright 2022 Stream.IO, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreMinimal.h"
#include "Subsystems/EngineSubsystem.h"
 
#include "ImageDownloadSubsystem.generated.h"
 
class UTexture2DDynamic;
using FHttpResponsePtr = TSharedPtr<class IHttpResponse, ESPMode::ThreadSafe>;
enum class EImageFormat : int8;
 
UCLASS()
class STREAMCHATUI_API UImageDownloadSubsystem final : public UEngineSubsystem
{
    GENERATED_BODY()
 
public:
    virtual void Initialize(FSubsystemCollectionBase& Collection) override;
    virtual bool ShouldCreateSubsystem(UObject* Outer) const override;
 
    void DownloadImage(const FString& Url, TFunction<void(UTexture2DDynamic*)>);
 
private:
    void CacheToMemory(const FString& Url, UTexture2DDynamic* Texture);
    UTexture2DDynamic* QueryMemoryCache(const FString& Url) const;
 
    void CacheToDisk(const FString& Url, const FHttpResponsePtr) const;
    UTexture2DDynamic* QueryDiskCache(const FString& Url);
 
    FString GetDiskPathForUrl(const FString& Url) const;
 
    UPROPERTY(Transient)
    TMap<FString, UTexture2DDynamic*> MemoryCache;
 
    // folders to save image files into on disk
    FString CacheFolder;
};