Running on isolate instance has not been initialized on windows

[alexaccaci]

Using version 0.4.0 quick_usb init doen't work on isolate. I'haven't this problem using the prevoius version 0.3.1. I've attached an example. Best Regards Alex

import 'dart:async'; import 'dart:isolate';

import 'package:flutter/material.dart'; import 'package:quick_usb/quick_usb.dart';

void main() async { WidgetsFlutterBinding.ensureInitialized();

runApp(MyHome()); }

class MyHome extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( appBar: AppBar( title: const Text('Plugin example app'), ), body: MyApp(), ), ); } }

class MyApp extends StatefulWidget { @override _MyAppState createState() => _MyAppState(); }

class _MyAppState extends State { @override void initState() { super.initState(); init(); }

Future init() async { UsbService.usbRecvPort = ReceivePort(); await Isolate.spawn(UsbService.loopUsb, UsbService.usbRecvPort!.sendPort); }

@override Widget build(BuildContext context) { return _buildColumn(); }

void log(String info) { ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(info))); }

Widget _buildColumn() { return Column( children: [ _init_exit(), _getDeviceList(), ], ); }

Widget _init_exit() { return Row( mainAxisAlignment: MainAxisAlignment.spaceEvenly, children: [ ElevatedButton( child: Text('init'), onPressed: () async { var init = await QuickUsb.init(); log('init $init'); }, ), ElevatedButton( child: Text('exit'), onPressed: () async { await QuickUsb.exit(); log('exit'); }, ), ], ); }

List? _deviceList;

Widget _getDeviceList() { return ElevatedButton( child: Text('getDeviceList'), onPressed: () async { _deviceList = await QuickUsb.getDeviceList(); log('deviceList $_deviceList'); }, ); } }

class UsbService { static SendPort? usbSendPort; static ReceivePort? usbRecvPort;

static void loopUsb(SendPort sendPort) async { ReceivePort p = ReceivePort(); sendPort.send(p.sendPort);

while (true) {
  await Future.delayed(const Duration(seconds: 1));
  try {
    var init = await QuickUsb.init();
    print('init $init');

    var list = await QuickUsb.getDeviceList();
    print(list);

    await QuickUsb.exit();
  } catch (e) {
    print(e);
  }
}

} }

[alexaccaci]

I have resolved the problem using the following article: https://medium.com/flutter/introducing-background-isolate-channels-7a299609cad8

But there is another small error in your code that needs to correct:

class QuickUsbWindows extends _QuickUsbDesktop { // For example/.dart_tool/flutter_build/generated_main.dart static registerWith() { QuickUsbPlatform.instance = QuickUsbMacos(); _libusb = Libusb(DynamicLibrary.open('libusb-1.0.23.dll')); } }

has to be changed with:

class QuickUsbWindows extends _QuickUsbDesktop { // For example/.dart_tool/flutter_build/generated_main.dart static registerWith() { QuickUsbPlatform.instance = QuickUsbWindows();//not QuickUsbMacos!!! _libusb = Libusb(DynamicLibrary.open('libusb-1.0.23.dll')); } }

Best regards Alex