ArchiveSaveCompressedProxy.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"
 
/*----------------------------------------------------------------------------
    FArchiveSaveCompressedProxy.
----------------------------------------------------------------------------*/
 
/**
 * FArchive Proxy to transparently write out compressed data to an array.
 */
class FArchiveSaveCompressedProxy : public FArchive
{
    /**
     * This enum and the following constructor is a workaround for VC compiler bug that prevents using attributes
     * on constructors without inline implementation. This should be removed when the deprecated ctor is removed.
     */
    enum EVS2015Redirector
    {
        Redirect
    };
    FArchiveSaveCompressedProxy(EVS2015Redirector, TArray<uint8>& InCompressedData, ECompressionFlags InCompressionFlags);
 
public:
    /** 
     * Constructor, initializing all member variables and allocating temp memory.
     *
     * @param   InCompressedData [ref]  Array of bytes that is going to hold compressed data
     * @param   InCompressionFormat     Compression format to use
     */
    UE_DEPRECATED(4.21, "Use the FName version of FArchiveSaveCompressedProxy constructor")
    FArchiveSaveCompressedProxy(TArray<uint8>& InCompressedData, ECompressionFlags InCompressionFlags)
        // Make sure to remove the EVS2015Redirector constructor when this constructor is removed
        : FArchiveSaveCompressedProxy(EVS2015Redirector::Redirect, InCompressedData, InCompressionFlags)
    {}
    FArchiveSaveCompressedProxy( TArray<uint8>& InCompressedData, FName InCompressionFormat, ECompressionFlags InCompressionFlags=COMPRESS_None);
 
    /** Destructor, flushing array if needed. Also frees temporary memory. */
    virtual ~FArchiveSaveCompressedProxy();
 
    /**
     * Flushes tmp data to array.
     */
    virtual void Flush();
 
    /**
     * Serializes data to archive. This function is called recursively and determines where to serialize
     * to 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 );
 
    /**
     * Seeking is only implemented internally for writing out compressed data and asserts otherwise.
     * 
     * @param   InPos   Position to seek to
     */
    virtual void Seek( int64 InPos );
 
    /**
     * @return current position in uncompressed stream in bytes.
     */
    virtual int64 Tell();
 
private:
    /** Array to write compressed data to.                  */
    TArray<uint8>&  CompressedData;
    /** Current index in 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 to temporary buffer of array.  */
    bool            bShouldSerializeToArray;
    /** Number of raw (uncompressed) bytes serialized.      */
    int64       RawBytesSerialized;
    /** Format to use for compression.                      */
    FName  CompressionFormat;
    /** Flags to use for compression.                       */
    ECompressionFlags CompressionFlags;
};