[ESP32 TTGO] My hardware key to operate my app (Ep.2/2 - Completing App)

ESP32_TTGO/my_hardware_key_demo_app/lib/controller/serial_controller.dart

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+import 'dart:async';
+import 'dart:typed_data';
+
+import 'package:flutter/material.dart';
+import 'package:get/get.dart';
+import 'package:usb_serial/transaction.dart';
+import 'package:usb_serial/usb_serial.dart';
+
+class SerialController extends GetxController {
+  UsbPort _port;
+  StreamSubscription<String> _subscription;
+  Transaction<String> _transaction;
+  int _deviceId;
+  TextEditingController textController;
+  String _keyFromDevice;
+  String logMessage = "";
+  final hardwareKeyConnected = false.obs;
+
+  Future<bool> _connectTo(device) async {
+    if (_subscription != null) {
+      _subscription.cancel();
+      _subscription = null;
+    }
+
+    if (_transaction != null) {
+      _transaction.dispose();
+      _transaction = null;
+    }
+
+    if (_port != null) {
+      _port.close();
+      _port = null;
+    }
+
+    if (device == null) {
+      _deviceId = null;
+      return true;
+    }
+
+    _port = await device.create();
+    if (!await _port.open()) {
+      return false;
+    }
+
+    _deviceId = device.deviceId;
+    await _port.setDTR(true);
+    await _port.setRTS(true);
+    await _port.setPortParameters(
+        115200, UsbPort.DATABITS_8, UsbPort.STOPBITS_1, UsbPort.PARITY_NONE);
+
+    _transaction = Transaction.stringTerminated(
+        _port.inputStream, Uint8List.fromList([13, 10]));
+
+    _subscription = _transaction.stream.listen((String line) {
+      _keyFromDevice = line;
+      textController.text = line;
+    });
+
+    return true;
+  }
+
+  void _getPorts() async {
+    List<UsbDevice> devices = await UsbSerial.listDevices();
+    print(devices);
+    bool targetDeviceFound = false;
+
+    devices.forEach((device) {
+      logMessage = "[Log] device pid: ${device.pid}, device vid: ${device.vid}";
+      if (device.pid == 60000 && device.vid == 4292) {
+        targetDeviceFound = true;
+
+        if (!hardwareKeyConnected.value) {
+          _connectTo(device).then((res) {
+            hardwareKeyConnected.value = res;
+            sendString("key?");
+            Get.snackbar("Device Status", "Connected!",
+                duration: Duration(seconds: 5));
+          });
+        }
+      }
+    });
+
+    if (!targetDeviceFound) {
+      hardwareKeyConnected.value = false;
+    }
+  }
+
+  void sendString(String text) async {
+    if (_port == null) return;
+    await _port.write(Uint8List.fromList(text.codeUnits));
+  }
+
+  Future<bool> validation() async {
+    if (textController.text == _keyFromDevice) {
+      sendString("done");
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  @override
+  void onInit() {
+    super.onInit();
+    textController = TextEditingController();
+    UsbSerial.usbEventStream.listen((UsbEvent event) {
+      _getPorts();
+    });
+    _getPorts();
+  }
+
+  @override
+  void onClose() {
+    textController?.dispose();
+    _connectTo(null);
+    super.onClose();
+  }
+}