如何从svg读取boost::geometry::model::polygon

#include <iostream>
#include <fstream>
#include <string>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/register/point.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <rapidxml.hpp>

namespace bg = boost::geometry;
namespace bgi = boost::geometry::index;

// 注册点类型
BOOST_GEOMETRY_REGISTER_POINT_2D(boost::geometry::model::d2::point_xy<double>, double, bg::cs::cartesian, x, y)

int main()
{
    // 打开SVG文件
    std::ifstream svgFile("example.svg");
    std::string svgContent((std::istreambuf_iterator<char>(svgFile)), std::istreambuf_iterator<char>());

    // 解析SVG内容
    rapidxml::xml_document<> doc;
    doc.parse<0>(&svgContent[0]);

    // 查找多边形元素
    rapidxml::xml_node<>* polygonNode = doc.first_node("svg")->first_node("polygon");

    // 提取顶点坐标
    std::string pointsStr = polygonNode->first_attribute("points")->value();
    std::vector<bg::model::d2::point_xy<double>> points;
    std::istringstream iss(pointsStr);
    double x, y;
    while (iss >> x >> y)
    {
        points.push_back(bg::model::d2::point_xy<double>(x, y));
    }

    // 创建boost::geometry::model::polygon对象
    bg::model::polygon<bg::model::d2::point_xy<double>> polygon;
    bg::assign_points(polygon, points);

    // 输出多边形信息
    std::cout << "Polygon area: " << bg::area(polygon) << std::endl;
    std::cout << "Polygon perimeter: " << bg::perimeter(polygon) << std::endl;

    return 0;
}