Compression.cpp

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/*
 * Compression.cpp
 *
 *  Created on: Sep 10, 2018
 *      Author: labm2414
 */

#include <Compression.h>
#include <zlib.h>
#include "find_object/utilite/ULogger.h"

namespace find_object {

std::vector<unsigned char> compressData(const cv::Mat & data)
{
        std::vector<unsigned char> bytes;
        if(!data.empty())
        {
                uLong sourceLen = uLong(data.total())*uLong(data.elemSize());
                uLong destLen = compressBound(sourceLen);
                bytes.resize(destLen);
                int errCode = compress(
                                                (Bytef *)bytes.data(),
                                                &destLen,
                                                (const Bytef *)data.data,
                                                sourceLen);

                bytes.resize(destLen+3*sizeof(int));
                *((int*)&bytes[destLen]) = data.rows;
                *((int*)&bytes[destLen+sizeof(int)]) = data.cols;
                *((int*)&bytes[destLen+2*sizeof(int)]) = data.type();

                if(errCode == Z_MEM_ERROR)
                {
                        UERROR("Z_MEM_ERROR : Insufficient memory.");
                }
                else if(errCode == Z_BUF_ERROR)
                {
                        UERROR("Z_BUF_ERROR : The buffer dest was not large enough to hold the uncompressed data.");
                }
        }
        return bytes;
}

cv::Mat uncompressData(const unsigned char * bytes, unsigned long size)
{
        cv::Mat data;
        if(bytes && size>=3*sizeof(int))
        {
                //last 3 int elements are matrix size and type
                int height = *((int*)&bytes[size-3*sizeof(int)]);
                int width = *((int*)&bytes[size-2*sizeof(int)]);
                int type = *((int*)&bytes[size-1*sizeof(int)]);

                data = cv::Mat(height, width, type);
                uLongf totalUncompressed = uLongf(data.total())*uLongf(data.elemSize());

                int errCode = uncompress(
                                                (Bytef*)data.data,
                                                &totalUncompressed,
                                                (const Bytef*)bytes,
                                                uLong(size));

                if(errCode == Z_MEM_ERROR)
                {
                        UERROR("Z_MEM_ERROR : Insufficient memory.");
                }
                else if(errCode == Z_BUF_ERROR)
                {
                        UERROR("Z_BUF_ERROR : The buffer dest was not large enough to hold the uncompressed data.");
                }
                else if(errCode == Z_DATA_ERROR)
                {
                        UERROR("Z_DATA_ERROR : The compressed data (referenced by source) was corrupted.");
                }
        }
        return data;
}
} /* namespace find_object */