How to detect that paper is loaded in automatic document feeder of TWAIN image scanner?

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If you need to detect that paper is loaded in automatic document feeder of TWAIN image scanner, you need to do the following steps:

First, check if TWAIN image scanner can detect the paper in the automatic document feeder - this can be done using the DocumentFeeder.PaperDetectable property.
Next, check if paper is loaded in the automatic document feeder - this can be done using the DocumentFeeder.Loaded property.

Here is an example that demonstrates how to detect if paper is loaded in the automatic document feeder of TWAIN device:

/// <summary>
/// Acquire images from the automatic document feeder of TWAIN device.
/// </summary>
public void AcquireImagesFromAdf(Vintasoft.Twain.Device device)
{
    // disable UI
    device.ShowUI = false;

    // open the device
    device.Open();
    // specify that color images must be acquired
    device.PixelType = Vintasoft.Twain.PixelType.RGB;
    // set the inches as unit of measure
    device.UnitOfMeasure = Vintasoft.Twain.UnitOfMeasure.Inches;
    // set the desired resolution of acquired images
    device.Resolution = new Vintasoft.Twain.Resolution(200f, 200f);

    // if device has the automatic document feeder
    if (device.HasFeeder)
    {
        // enable feeder
        device.DocumentFeeder.Enabled = true;
        // specify that application want to acquire all pages from the feeder
        device.XferCount = -1;

        // if pages can be scanned in duplex mode
        if (device.DocumentFeeder.DuplexMode != Vintasoft.Twain.DuplexMode.None)
            // enable duplex scanning
            device.DocumentFeeder.DuplexEnabled = true;

        // if feeder can detect paper
        if (device.DocumentFeeder.PaperDetectable)
        {
            // if feeder is loaded
            if (device.DocumentFeeder.Loaded)
                // acquire images asynchronously
                device.Acquire();
        }
        // if feeder cannot detect paper
        else
            // acquire images asynchronously
            device.Acquire();
    }
}

VB.NET

''' <summary>
''' Acquire images from the automatic document feeder of TWAIN device.
''' </summary>
Public Sub AcquireImagesFromAdf(device As Vintasoft.Twain.Device)
    ' disable UI
    device.ShowUI = False

    ' open the device
    device.Open()
    ' specify that color images must be acquired
    device.PixelType = Vintasoft.Twain.PixelType.RGB
    ' set the inches as unit of measure
    device.UnitOfMeasure = Vintasoft.Twain.UnitOfMeasure.Inches
    ' set the desired resolution of acquired images
    device.Resolution = New Vintasoft.Twain.Resolution(200.0F, 200.0F)

    ' if device has the automatic document feeder
    If device.HasFeeder Then
        ' enable feeder
        device.DocumentFeeder.Enabled = True
        ' specify that application want to acquire all pages from the feeder
        device.XferCount = -1

        ' if pages can be scanned in duplex mode
        If device.DocumentFeeder.DuplexMode <> Vintasoft.Twain.DuplexMode.None Then
            ' enable duplex scanning
            device.DocumentFeeder.DuplexEnabled = True
        End If

        ' if feeder can detect paper
        If device.DocumentFeeder.PaperDetectable Then
            ' if feeder is loaded
            If device.DocumentFeeder.Loaded Then
                ' acquire images asynchronously
                device.Acquire()
            End If
        Else
            ' if feeder cannot detect paper
            ' acquire images asynchronously
            device.Acquire()
        End If
    End If
End Sub

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