//XtensionRegisterWriter registers the writer wrapped by XtensionWrapWriter
//with the surface so that it does not get garbage collected until libcairo
//releases the device.
//
//See XtensionWrapWriter for more information.
func (d *XtensionDevice) XtensionRegisterWriter(w unsafe.Pointer) {
if err := d.Err(); err != nil {
go_write_callback_reaper(w)
}
W := (*writer)(w)
W.id = d.id()
C.cairo_device_set_user_data(d.d, wkey, w, C.wreaper_getter())
storeWriter(W)
}
func deviceSetID(d *C.cairo_device_t) {
if C.cairo_device_get_user_data(d, idkey) != nil {
return
}
C.cairo_device_set_user_data(d, idkey, generateID(), free)
}