使用 boost zlib 从 std::vector 中的文件中读取压缩的 zraw 数据

Question

我正在尝试使用 boost 和 zlib 读取压缩（3d 体素化图像）文件，但到目前为止没有成功。

我的目标是解压缩数据并将它们存储在 std::vector 中。除了 boost 文档的示例之外，是否还有来自此任务的更具体的示例？

这是我尝试做的示例：

std::vector<DATATYPE> data;

{
  ifstream file_in("image.zraw", ios_base::in | ios_base::binary);
  filtering_istream in;
  in.push(zlib_decompressor());
  in.push(file_in);

  //copy somehow memory from in the vector data... DATATYPE is the type of data to be stored in the vector...
}

提前致谢，康斯坦丁诺斯

Answer 1

既然你不能具体说明，我就运行假设一下：

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#include <boost/iostreams/filtering_stream.hpp>
#include <boost/iostreams/filter/zlib.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <fstream>

namespace bio = boost::iostreams;

template <typename T>
void write_data(std::string const& fname, std::vector<T> const& data) {
    std::ofstream ofs(fname, std::ios_base::binary);
    bio::filtering_ostream out;

    out.push(bio::zlib_compressor());
    out.push(ofs);

    boost::archive::binary_oarchive oa(out);
    oa << data;
}

template <typename T>
std::vector<T> read_data(std::string const& fname) {
    std::vector<T> result;

    std::ifstream file_in(fname, std::ios_base::binary);
    bio::filtering_istream in;

    in.push(bio::zlib_decompressor());
    in.push(file_in);

    boost::archive::binary_iarchive ia(in);
    ia >> result;

    return result;
}

#include <iostream>

int main() {
    write_data("floats.zraw", std::vector<float> { 1,2,3 });
    write_data("ints.zraw",   std::vector<int>   { 4,5,6 });

    auto floats = read_data<float>("floats.zraw");
    auto ints   = read_data<int>("ints.zraw");

    std::copy(floats.begin(), floats.end(), std::ostream_iterator<float>(std::cout << '\n', " "));
    std::copy(ints  .begin(), ints  .end(), std::ostream_iterator<int  >(std::cout << '\n', " "));
}

版画

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4 5 6

它使用Boost Serialization 和Boost Iostreams 实现二进制（反）序列化为压缩文件。该格式是通用的，不限于 POD 数据类型，并且不 platform/library 版本无关。

Answer 2

解决我的问题我post可能对其他人有帮助的答案

 previous stuff.....

// Clear the data storing vector of the image.
this->data_.clear();

// Reserve enough space for the data vector according to image's size.
this->data_.reserve(this->num_voxels_);

// Here happens the decompression.
{
std::ifstream file_in("../data/image.zraw", std::ios::in | std::ios_base::binary);
boost::iostreams::filtering_istream in;

in.push(boost::iostreams::zlib_decompressor());
in.push(file_in);

// Write the data from the filtering istream to the data_ vector.
char *dptr = reinterpret_cast<char*>(this->data_.data());

// DATATYPE is the templated storage type of the vector.
for(int i=0;i<sizeof(DATATYPE)*this->num_voxels_;i++)
    in.read(&dptr[i],1);
}

next stuff.......

使用 boost zlib 从 std::vector 中的文件中读取压缩的 zraw 数据

Read compressed zraw data from file in std::vector with boost zlib

c++

boost

zlib