gdk/gdk.go
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
}
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
}
// SavePNG is a wrapper around gdk_pixbuf_save().
// Compression is a number between 0...9