void paint_caps(QPainter &p, QLineF *const lines,
std::vector< std::pair<int64_t, bool> > &edges,
bool level, double samples_per_pixel, double pixels_offset,
void paint_caps(QPainter &p, QLineF *const lines,
std::vector< std::pair<int64_t, bool> > &edges,
bool level, double samples_per_pixel, double pixels_offset,