zstream.h

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/*
    This file is part of Mitsuba, a physically based rendering system.

    Copyright (c) 2007-2014 by Wenzel Jakob and others.

    Mitsuba is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License Version 3
    as published by the Free Software Foundation.

    Mitsuba is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once
#if !defined(__MITSUBA_CORE_ZSTREAM_H_)
#define __MITSUBA_CORE_ZSTREAM_H_

#include <mitsuba/mitsuba.h>
#include <zlib.h>

/// Buffer size used to communicate with zlib. The larger, the better.
#define ZSTREAM_BUFSIZE 32768

MTS_NAMESPACE_BEGIN

/**
 * \brief Transparent compression/decompression stream based on \c zlib.
 *
 * This class transparently decompresses and compresses reads and writes
 * to a nested stream, respectively.
 *
 * \ingroup libcore
 */
class MTS_EXPORT_CORE ZStream : public Stream {
public:
        // =============================================================
        //! @{ \name Constructors
        // =============================================================
        enum EStreamType {
                /// A raw deflate stream
                EDeflateStream,
                /// A gzip-compatible stream
                EGZipStream
        };

        /// Create a new compression stream
        ZStream(Stream *childStream, EStreamType streamType = EDeflateStream,
                int level = Z_DEFAULT_COMPRESSION);

        //! @}
        // =============================================================

        // =============================================================
        //! @{ \name Compression stream-specific features
        // =============================================================

        /// Return the child stream of this compression stream
        inline const Stream *getChildStream() const { return m_childStream.get(); }

        /// Return the child stream of this compression stream
        inline Stream *getChildStream() { return m_childStream; }

        //! @}
        // =============================================================

        // =============================================================
        //! @{ \name Implementation of the Stream interface
        // =============================================================

        void read(void *ptr, size_t size);
        void write(const void *ptr, size_t size);
        void seek(size_t pos);
        size_t getPos() const;
        size_t getSize() const;
        void truncate(size_t size);
        void flush();
        bool canWrite() const;
        bool canRead() const;

        //! @}
        // =============================================================

        /// Return a string representation
        std::string toString() const;

        MTS_DECLARE_CLASS()
protected:
        // \brief Virtual destructor
        virtual ~ZStream();
private:
        ref<Stream> m_childStream;
        z_stream m_deflateStream, m_inflateStream;
        uint8_t m_deflateBuffer[ZSTREAM_BUFSIZE];
        uint8_t m_inflateBuffer[ZSTREAM_BUFSIZE];
        bool m_didWrite;
};

MTS_NAMESPACE_END

#endif /* __MITSUBA_CORE_ZSTREAM_H_ */