destroy method
void
destroy()
Implementation
void destroy() async {
if (!arThreadReady) {
return;
}
arThreadReady = false;
// We send a Destroy request and wait for a response before killing the thread
var reqId = ++_reqId;
var res = Completer();
_cbs[reqId] = res;
var msg = Request(reqId: reqId, method: 'destroy');
_toDetectorThread.send(msg);
// Wait for the detector to acknoledge the destory and kill the thread
await res.future;
_detectorThread.kill();
}