<SerializableAttribute()>
Public Class TwainException 
   Inherits Leadtools.LeadtoolsException
   Implements _Exception, ISerializable 

Dim instance As TwainException

[SerializableAttribute()]
public class TwainException : Leadtools.LeadtoolsException, _Exception, ISerializable  

[SerializableAttribute()]
public ref class TwainException : public Leadtools.LeadtoolsException, _Exception, ISerializable  

Public Sub _twainSession_AcquirePage(ByVal sender As Object, ByVal e As TwainAcquirePageEventArgs)
   Application.DoEvents()
   If Not e.Image Is Nothing Then
      e.Image.Dispose()
   End If

   e.Cancel = False
End Sub


Public Sub TwainExceptionExample(ByVal parent As IWin32Window)
   Dim session As TwainSession = Nothing

   Try
      ' initialize a new TWAIN session
      session = New TwainSession()
      session.Startup(parent, "manufacturer", "productFamily", "version", "application", TwainStartupFlags.None)
      AddHandler session.AcquirePage, AddressOf _twainSession_AcquirePage

      ' acquire a page, if paper jam, allow the user to retry
      Dim done As Boolean = False
      Do While Not done
         Try
            Dim res As DialogResult = session.Acquire(TwainUserInterfaceFlags.Modal Or TwainUserInterfaceFlags.Show)
            MessageBox.Show("Success")
            done = True
         Catch ex As TwainException
            If ex.Code = TwainExceptionCode.PaperJam Then
               If MessageBox.Show("Paper jam.  Fix and retry?", "TWAIN", MessageBoxButtons.YesNo) = DialogResult.No Then
                  done = True
               End If
            Else
               ' other error, propogate
               Throw ex
            End If
         End Try
      Loop
   Catch ex As TwainException
      MessageBox.Show(String.Format("Twain error:{0}Code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message))
   Catch ex As Exception
      MessageBox.Show(String.Format("Other error: Message:{0}", ex.Message))
   Finally
      If Not session Is Nothing Then
         session.Shutdown()
      End If
   End Try
End Sub

public void _twainSession_AcquirePage(object sender, TwainAcquirePageEventArgs e)
{
   Application.DoEvents();
   if(e.Image != null)
      e.Image.Dispose();

   e.Cancel = false;
}


public void TwainExceptionExample(IWin32Window parent)
{
   TwainSession session = null;

   try
   {
      // initialize a new TWAIN session
      session = new TwainSession();
      session.Startup(parent, "manufacturer", "productFamily", "version", "application", TwainStartupFlags.None);
      session.AcquirePage += new EventHandler<TwainAcquirePageEventArgs>(_twainSession_AcquirePage);

      // acquire a page, if paper jam, allow the user to retry
      bool done = false;
      while(!done)
      {
         try
         {
            DialogResult res = session.Acquire(TwainUserInterfaceFlags.Modal | TwainUserInterfaceFlags.Show);
            MessageBox.Show("Success");
            done = true;
         }
         catch(TwainException ex)
         {
            if(ex.Code == TwainExceptionCode.PaperJam)
            {
               if(MessageBox.Show("Paper jam.  Fix and retry?", "TWAIN", MessageBoxButtons.YesNo) == DialogResult.No)
                  done = true;
            }
            else
            {
               // other error, propogate
               throw ex;
            }
         }
      }
   }
   catch(TwainException ex)
   {
      MessageBox.Show(string.Format("Twain error:{0}Code: {1}{0}Message: {2}", Environment.NewLine, ex.Code, ex.Message));
   }
   catch(Exception ex)
   {
      MessageBox.Show(string.Format("Other error: Message:{0}", ex.Message));
   }
   finally
   {
      if(session != null)
         session.Shutdown();
   }
}