SDK version 1.1.2 Error with Twain driver. "The selected scanner is offline".

[bernhard-bernan]

Hello, Im using SDK version 1.1.2 and im getting error "The selected scanner is offline" when scanning page. This error doesnt happen with NAPS2 7.5.2 desktop app. Im getting it only in SDK in my own project. This is pseudo code that kinda is similar to real code:

public class ScannerManager : IScannerManager
{
    private readonly ScanController _scanController;

    public ScannerManager()
    {
      var scanningContext = new ScanningContext(new ImageSharpImageContext());
      scanningContext.SetUpWin32Worker();
      _scanController = new ScanController(scanningContext);
      _scanController.PropagateErrors = false;
      _scanController.ScanEnd += OnScanEnd;
    }

    public async Task<List<byte[]>> ScanPagesBasedOnOptionsAsync(ScanOptions options)
    {
      var imageList = new List<byte[]>();

      await foreach (var img in _scanController.Scan(options))
      {
        var imgBytes = img.SaveToMemoryStream(ImageFileFormat.Jpeg).ToArray();
        imageList.Add(imgBytes);
      }
      return imageList;
    }

    public async Task<ScanDevice> FindTwainDeviceByNameAsync(string name)
    {
      var options = new ScanOptions() { Driver = Driver.Twain, };
      return await FindDeviceByNameAsync(name, options);
    }

    private async Task<ScanDevice> FindDeviceByNameAsync(string name, ScanOptions options)
    {
      var devices = await _scanController.GetDeviceList(options);

      foreach (var device in devices)
      {
        if (device.Name.Equals(name) && device.Driver.Equals(options.Driver))
        {
          return device;
        }
      }

      throw new ScannerException($"{ExceptionMessages.ScannerNotFound}:{name}");
    }

    private void OnScanEnd(object? sender, ScanEndEventArgs args)
    {
      if (args == null || args.Error == null)
      {
                return;
      }
      throw new ScannerException(args.Error.Message);
    }

}



public class ScannersService
{
  private readonly IScannerManager _scannerManager;

  public ScannersService(IScannerManager scannerManager)
  {
    _imageManager = imageManager;
  }

  public async Task ScanPage(ScannerRecord scannerRecord)
  {
    ScanDevice device = await _scannerManager.FindTwainDeviceByNameAsync(scannerRecord.Name);

    ScanOptions options = CreateScannerOptions(scannerRecord, device);
    try
    {

      List<byte[]> scannedImages = await _scannerManager.ScanPagesBasedOnOptionsAsync(options);
    }
    catch (Exception e)
    {
      throw new ScannerException(e.Message);
    }
  }

  private ScanOptions CreateScannerOptions(ScannerRecord scannerRecord, ScanDevice device) {
    // Some logic to get source type by record value(PaperSource - Auto, Flatbed, Feeder, Duplex;)
    PaperSource paperSource = GetPaperSourceTypeByRecord(scannerRecord);

    return new()
    {
      Device = device,
      PaperSource = paperSource,
      PageSize = NAPS2.Images.PageSize.A4,
      Dpi = scannerRecord.DpiQuality.Value,
      BitDepth = NAPS2.Images.BitDepth.Color,
      Driver = Driver.Twain,
    };
  }

}

Could it be related to how i set options, or that i find device before scanning ? I checked your code and to me it seems that you create new Device object instead of searching for device, could that be the problem ? :

    private async Task<bool> PopulateDevice(ScanProfile scanProfile, ScanOptions options)
    {
        // If a device wasn't specified, prompt the user to pick one
        if (string.IsNullOrEmpty(scanProfile.Device?.ID))
        {
            options.Device = (await _devicePrompt.PromptForDevice(options, false)).Device;
            if (options.Device == null)
            {
                return false;
            }

            // Persist the device in the profile if configured to do so
            if (_config.Get(c => c.AlwaysRememberDevice))
            {
                scanProfile.Device = ScanProfileDevice.FromScanDevice(options.Device);
                _profileManager.Save();
            }
        }
        else
        {
            options.Device = scanProfile.Device?.ToScanDevice(options.Driver);
        }

        return true;
    }

Any help appreciated! Also wasnt sure if i should post it here or in github =o