Texture2DMipDataProvider_IO.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
Texture2DMipDataProvider_IO.h : Implementation of FTextureMipDataProvider using cooked file IO.
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "Streaming/TextureMipDataProvider.h"
#include "Async/AsyncFileHandle.h"
#include "Serialization/BulkData.h"
 
class FTexture2DMipDataProvider_IO : public FTextureMipDataProvider
{
public:
 
    FTexture2DMipDataProvider_IO(const UTexture* InTexture, bool InPrioritizedIORequest);
    ~FTexture2DMipDataProvider_IO();
 
    // ********************************************************
    // ********* FTextureMipDataProvider implementation **********
    // ********************************************************
 
    void Init(const FTextureUpdateContext& Context, const FTextureUpdateSyncOptions& SyncOptions) final override;
    int32 GetMips(const FTextureUpdateContext& Context, int32 StartingMipIndex, const FTextureMipInfoArray& MipInfos, const FTextureUpdateSyncOptions& SyncOptions) final override;
    bool PollMips(const FTextureUpdateSyncOptions& SyncOptions) final override;
    void AbortPollMips() final override;
    void CleanUp(const FTextureUpdateSyncOptions& SyncOptions) final override;
    void Cancel(const FTextureUpdateSyncOptions& SyncOptions) final override;
    ETickThread GetCancelThread() const final override;
 
protected:
 
    // A structured with information about which file contains which mips.
    struct FIORequest
    {
        FIoFilenameHash FilenameHash = INVALID_IO_FILENAME_HASH;
        TUniquePtr<IBulkDataIORequest> BulkDataIORequest;
    };
 
    // Pending async requests created in GetMips().
    TArray<FIORequest, TInlineAllocator<MAX_TEXTURE_MIP_COUNT>> IORequests;
 
    // The asset name, used to log IO errors.
    FName TextureName;
    // Whether async read requests must be created with high priority (executes faster). 
    bool bPrioritizedIORequest = false;
    // Whether async read requests where cancelled for any reasons.
    bool bIORequestCancelled = false;
    // Whether async read requests were required to abort through AbortPollMips().
    bool bIORequestAborted = false;
 
    // A callback to be executed once all IO pending requests are completed.
    FBulkDataIORequestCallBack AsyncFileCallBack;
 
    // Helper to configure the AsyncFileCallBack.
    void SetAsyncFileCallback(const FTextureUpdateSyncOptions& SyncOptions);
 
    // Release / cancel any pending async file requests.
    void ClearIORequests();
};