ArchiveLoadCompressedProxy.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "CoreTypes.h"
#include "Misc/Compression.h"
#include "Misc/CompressionFlags.h"
#include "Serialization/Archive.h"
#include "UObject/NameTypes.h"
 
/*----------------------------------------------------------------------------
    FArchiveLoadCompressedProxy.
----------------------------------------------------------------------------*/
 
/**
 * FArchive Proxy to transparently load compressed data from an array.
 */
class FArchiveLoadCompressedProxy : public FArchive
{
public:
    FArchiveLoadCompressedProxy(const TArray<uint8>& InCompressedData, FName CompressionFormat, ECompressionFlags InCompressionFlags=COMPRESS_NoFlags);
 
    /** Destructor, freeing temporary memory. */
    virtual ~FArchiveLoadCompressedProxy();
 
    /**
     * Serializes data from archive. This function is called recursively and determines where to serialize
     * from and how to do so based on internal state.
     *
     * @param   Data    Pointer to serialize to
     * @param   Count   Number of bytes to read
     */
    virtual void Serialize( void* Data, int64 Count );
 
    /**
     * Seeks to the passed in position in the stream. This archive only supports forward seeking
     * and implements it by serializing data till it reaches the position.
     */
    virtual void Seek( int64 InPos );
 
    /**
     * @return current position in uncompressed stream in bytes.
     */
    virtual int64 Tell();
 
private:
    /**
     * Flushes tmp data to array.
     */
    void DecompressMoreData();
 
    /** Array to write compressed data to.                      */
    const TArray<uint8>&    CompressedData;
    /** Current index into compressed data array.               */
    int32           CurrentIndex;
    /** Pointer to start of temporary buffer.                   */
    uint8*          TmpDataStart;
    /** Pointer to end of temporary buffer.                     */
    uint8*          TmpDataEnd;
    /** Pointer to current position in temporary buffer.        */
    uint8*          TmpData;
    /** Whether to serialize from temporary buffer of array.    */
    bool            bShouldSerializeFromArray;
    /** Number of raw (uncompressed) bytes serialized.          */
    int64           RawBytesSerialized;
    /** Compression method                                      */
    FName           CompressionFormat;
    /** Flags used for compression.                             */
    ECompressionFlags CompressionFlags;
};