Flutter UI freezes on hash check - flutter

Question

I have a program that will check a password with bcrypt library, this is quite computing intensive, so as a result the UI will be stuck for like 2 seconds. It is very annoying and I cannot figure out what to do to stop it.
I want a loader to be shown when the password is being checked.
This is my code:
class _MyWidgetState<MyWidget> extends State{
build() {
return GetPassCode(PassCodeType.ENTER,
onDone: ({context, data}) async {
unlock(state, data?['password'] ?? '', Languages.of(context));
}, goBack: () {}, data: {});
}
unlock(userState, String? password, Languages strings) async {
final user = userState.currentUser;
if (!(await user.checkPassword(password))) {
return;
}
}
context.read<LockCubit>().unlock();
}
}

Answer 1

you can put the caculating into a isolate.
https://api.flutter-io.cn/flutter/dart-isolate/dart-isolate-library.html
here's some example code:
class IsoMessage {
final SendPort? sendPort;
final List<String> args;
IsoMessage(this.sendPort, this.args);
}
String myCaculate(IsoMessage message) {
String result = message.args[0][0] + message.args[1][1];
message.sendPort?.send(result);
return result;
}
here's how to calling the func
var port = ReceivePort();
port.listen((message) {
print("onData: $message");
}, onDone: () {
print('iso close');
}, onError: (error) {
print('iso error: $error');
});
IsoMessage message = IsoMessage(port.sendPort,["asd", "dsa"]);
Isolate.spawn<IsoMessage>(myCaculate, message);