FileRegions.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "Containers/ArrayView.h"
#include "HAL/Platform.h"
#include "PixelFormat.h"
 
class FCbFieldView;
class FCbWriter;
 
// Describes the type of data found in a given file region.
enum class EFileRegionType : uint8
{
    // NOTE: Enum values here must match those in AutomationUtils/FileRegions.cs
    None = 0,
 
    // @todo re-number these and bump texture DDC key
    // Texture data types
    BC1 = 2,
    BC2 = 5,
    BC3 = 6,
    BC4 = 3,
    BC5 = 7
};
 
// Represents a region of logically related bytes within a larger block of cooked data.
// Regions are used to improve data compression and patching on some platforms.
struct FFileRegion
{
    static CORE_API const TCHAR* RegionsFileExtension;
 
    uint64 Offset;
    uint64 Length;
    EFileRegionType Type;
 
    FFileRegion()
        : Offset(0)
        , Length(0)
        , Type(EFileRegionType::None)
    {}
 
    FFileRegion(uint64 InOffset, uint64 InLength, EFileRegionType InType)
        : Offset(InOffset)
        , Length(InLength)
        , Type(InType)
    {}
 
    static CORE_API void AccumulateFileRegions(TArray<FFileRegion>& InOutRegions, int64 EntryOffset, int64 PayloadOffset, int64 EndOffset, TArrayView<const FFileRegion> InnerFileRegions);
    static CORE_API void SerializeFileRegions(class FArchive& Ar, TArray<FFileRegion>& Regions);
 
    CORE_API friend FCbWriter& operator<<(FCbWriter& Writer, const FFileRegion& Region);
    static CORE_API bool LoadFromCompactBinary(FCbFieldView Obj, FFileRegion& OutRegion);
 
    static inline EFileRegionType SelectType(EPixelFormat Format)
    {
        switch (Format)
        {
        case PF_DXT1: return EFileRegionType::BC1;
        case PF_DXT3: return EFileRegionType::BC2;
        case PF_DXT5: return EFileRegionType::BC3;
        case PF_BC4:  return EFileRegionType::BC4;
        case PF_BC5:  return EFileRegionType::BC5;
        }
 
        return EFileRegionType::None;
    }
};