int y, int left, const int64_t start, const int64_t end,
const double pixels_offset, const double samples_per_pixel);
void paint_envelope(QPainter &p,
int y, int left, const int64_t start, const int64_t end,
const double pixels_offset, const double samples_per_pixel);
void paint_envelope(QPainter &p,
int y, int left, const int64_t start, const int64_t end,
const double pixels_offset, const double samples_per_pixel);
int y, int left, const int64_t start, const int64_t end,
const double pixels_offset, const double samples_per_pixel);