如何将vector<cv::Point2d>转换为vector<cv::Point>？

Question

如何将vector<cv::Point2d>转换为vector<cv::Point>有什么简单的解决方案吗？像这样的东西，C++ convert vector to vector？

这些类型是模板化的：

typedef Point_<double> Point2d;

typedef Point_<int> Point2i;
typedef Point2i Point;


/*!
  template 2D point class.

  The class defines a point in 2D space. Data type of the point coordinates is specified
  as a template parameter. There are a few shorter aliases available for user convenience.
  See cv::Point, cv::Point2i, cv::Point2f and cv::Point2d.
*/
template<typename _Tp> class Point_
{
public:
    typedef _Tp value_type;

    // various constructors
    Point_();
    Point_(_Tp _x, _Tp _y);
    Point_(const Point_& pt);
    Point_(const CvPoint& pt);
    Point_(const CvPoint2D32f& pt);
    Point_(const Size_<_Tp>& sz);
    Point_(const Vec<_Tp, 2>& v);

    Point_& operator = (const Point_& pt);
    //! conversion to another data type
    template<typename _Tp2> operator Point_<_Tp2>() const;

    //! conversion to the old-style C structures
    operator CvPoint() const;
    operator CvPoint2D32f() const;
    operator Vec<_Tp, 2>() const;

    //! dot product
    _Tp dot(const Point_& pt) const;
    //! dot product computed in double-precision arithmetics
    double ddot(const Point_& pt) const;
    //! cross-product
    double cross(const Point_& pt) const;
    //! checks whether the point is inside the specified rectangle
    bool inside(const Rect_<_Tp>& r) const;

    _Tp x, y; //< the point coordinates
};

Answer 1

您可以使用向量范围构造函数完全按照此处所述进行操作

#include <opencv2\opencv.hpp>
#include <vector>
using namespace cv;
using namespace std;

int main()
{
    vector<Point2d> vd{ { 1.1, 2.2 }, { 3.3, 4.4 }, {5.5, 6.6} };
    vector<Point> v(vd.begin(), vd.end());

    // Print for debug
    copy(vd.begin(), vd.end(), ostream_iterator<Point2d>(cout, " "));
    cout << endl;
    copy(v.begin(), v.end(), ostream_iterator<Point>(cout, " "));

    return 0;
}

这是可行的，因为您可以使用以下命令从Point2d构建Point：

template<typename _Tp> template<typename _Tp2> inline Point_<_Tp>::operator Point_<_Tp2>() const
{ return Point_<_Tp2>(saturate_cast<_Tp2>(x), saturate_cast<_Tp2>(y)); }

Answer 2

由于不存在从cv::Point2D到cv::Point的转换，我建议使用lambda (未测试)：

vector<cv::Point2d> src ;
vector<cv::Point> dest ;

std::copy(src.begin(), 
          src.end(), 
          [&dest](const cv::Point2d &item) {
          dest.push_back(cv::Point(pt.x, pt.y)) ;}) ;