How to detect paper jam when acquiring images from TWAIN device?

In This Topic

Kodak scanner can send asynchronous event when paper is jammed, scanner is switched off, etc.
TWAIN Advanced Demo shows how to work with asynchronous events of device.

Here is an example that demonstrates how to detect when paper is jammed when acquiring images from TWAIN device:

/// <summary>
/// Detects the paper jamm.
/// </summary>
public void DetectPaperJam(Vintasoft.Twain.Device device)
{
    // disable device UI
    device.ShowUI = false;
    // disable device when images are acquired
    device.DisableAfterAcquire = true;

    // open the device
    device.Open();

    // set device settings
    device.PixelType = Vintasoft.Twain.PixelType.RGB;
    device.UnitOfMeasure = Vintasoft.Twain.UnitOfMeasure.Inches;
    device.Resolution = new Vintasoft.Twain.Resolution(300f, 300f);

    try
    {
        // get events supported by device
        Vintasoft.Twain.DeviceEventId[] supportedDeviceEvents = device.GetSupportedAsyncEvents();
        // for each supported event
        for (int i = 0; i < supportedDeviceEvents.Length; i++)
        {
            // if device can report when paper is jammed
            if (supportedDeviceEvents[i] == Vintasoft.Twain.DeviceEventId.PaperJam)
            {
                // specify that device must report when paper is jammed
                device.AsyncEvents = new Vintasoft.Twain.DeviceEventId[] { Vintasoft.Twain.DeviceEventId.PaperJam };

                // subscribe to the device event
                device.AsyncEvent += new System.EventHandler<Vintasoft.Twain.DeviceAsyncEventArgs>(device_DeviceEvent);

                break;
            }
        }
    }
    catch (System.Exception ex)
    {
        System.Console.WriteLine(ex.ToString());
    }

    // subscribe to the Device.ImageAcquired, Device.ScanCompleted, ... events
    //...

    // acquire images from device
    device.Acquire();
}

/// <summary>
/// Occurred the device event.
/// </summary>
private void device_DeviceEvent(object sender, Vintasoft.Twain.DeviceAsyncEventArgs e)
{
    System.Console.WriteLine("Paper is jammed.");
}

VB.NET

''' <summary>
''' Detects the paper jamm.
''' </summary>
Public Sub DetectPaperJam(device As Vintasoft.Twain.Device)
    ' disable device UI
    device.ShowUI = False
    ' disable device when images are acquired
    device.DisableAfterAcquire = True

    ' open the device
    device.Open()

    ' set device settings
    device.PixelType = Vintasoft.Twain.PixelType.RGB
    device.UnitOfMeasure = Vintasoft.Twain.UnitOfMeasure.Inches
    device.Resolution = New Vintasoft.Twain.Resolution(300.0F, 300.0F)

    Try
        ' get events supported by device
        Dim supportedDeviceEvents As Vintasoft.Twain.DeviceEventId() = device.GetSupportedAsyncEvents()
        ' for each supported event
        For i As Integer = 0 To supportedDeviceEvents.Length - 1
            ' if device can report when paper is jammed
            If supportedDeviceEvents(i) = Vintasoft.Twain.DeviceEventId.PaperJam Then
                ' specify that device must report when paper is jammed
                device.AsyncEvents = New Vintasoft.Twain.DeviceEventId() {Vintasoft.Twain.DeviceEventId.PaperJam}

                ' subscribe to the device event
                AddHandler device.AsyncEvent, New System.EventHandler(Of Vintasoft.Twain.DeviceAsyncEventArgs)(AddressOf device_DeviceEvent)

                Exit For
            End If
        Next
    Catch ex As System.Exception
        System.Console.WriteLine(ex.ToString())
    End Try

    ' subscribe to the Device.ImageAcquired, Device.ScanCompleted, ... events
    '...

    ' acquire images from device
    device.Acquire()
End Sub

''' <summary>
''' Occurred the device event.
''' </summary>
Private Sub device_DeviceEvent(sender As Object, e As Vintasoft.Twain.DeviceAsyncEventArgs)
    System.Console.WriteLine("Paper is jammed.")
End Sub

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