硬解jpeg的exif信息

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <sstream>
#include <string>

struct ExifData {
    std::string cameraModel;
    std::string creationDate;
    int rating;
    std::string description;
    int xResolution;
    int yResolution;
    int resolutionUnit; // 1 = no-unit, 2 = inch, 3 = cm
};



// 查找和提取 Exif 数据
std::string findAndExtractExifData(const std::vector<unsigned char>& imageData) {
    // 查找 Exif 数据的开始
    std::vector<unsigned char> startMarker(2) ;
     startMarker[0] = 0xFF;
     startMarker[1] = 0xE1;
    auto startIter = std::search(imageData.begin(), imageData.end(), startMarker.begin(), startMarker.end());
    if (startIter == imageData.end()) {
        std::cout << "未找到 Exif 数据的开始" << std::endl;
        return "";
    }

    // 获取 Exif 数据的长度
    auto exifLengthIter = startIter + 2;
    unsigned short exifLength = (static_cast<unsigned short>(*(exifLengthIter)) << 8) | static_cast<unsigned short>(*(exifLengthIter + 1));
    std::cout << "Exif 数据长度: " << exifLength << std::endl;

    // 提取 Exif 数据
    std::vector<unsigned char> exifData(exifLength);
    std::copy(startIter, startIter + exifLength, exifData.begin());

    // 返回 Exif 数据的字符串形式
    return std::string(reinterpret_cast<char*>(exifData.data()), exifData.size());
}

int main() {
    // 从 JPEG 图像文件中读取数据
    std::ifstream file("your_image_path/image.jpg", std::ios::binary | std::ios::ate);
    if (!file.is_open()) {
        std::cerr << "无法打开图像文件" << std::endl;
        return 1;
    }

    std::streamsize fileSize = file.tellg();
    file.seekg(0, std::ios::beg);

    std::vector<unsigned char> imageData(fileSize);
    if (!file.read(reinterpret_cast<char*>(imageData.data()), fileSize)) {
        std::cerr << "无法读取图像文件" << std::endl;
        return 1;
    }

    // 查找并提取 Exif 数据
    std::string exifData = findAndExtractExifData(imageData);

    // 输出 Exif 数据
    std::cout << exifData << std::endl;

    return 0;
}