code: func (v *Pixbuf) SavePNG(path string, compression int) error {
  	cpath := C.CString(path)
  	ccompression := C.CString(strconv.Itoa(compression))
  	defer C.free(unsafe.Pointer(cpath))
  	defer C.free(unsafe.Pointer(ccompression))
  
  	var err *C.GError
  	c := C._gdk_pixbuf_save_png(v.native(), cpath, &err, ccompression)
  	if !gobool(c) {
  		defer C.g_error_free(err)
  		return errors.New(C.GoString((*C.char)(err.message)))
  	}
  	return nil
  }
docs: // SavePNG is a wrapper around gdk_pixbuf_save().
  // Compression is a number between 0...9