TwainException Class

Summary
The exception that is thrown when a TWAIN error occurs.
Syntax
C#
C++
[SerializableAttribute()] 
public class TwainException : LeadtoolsException 
vb[VB Syntax] 
<SerializableAttribute()> 
Public Class TwainException  
   Inherits LeadtoolsException 
   Implements System.Runtime.InteropServices._Exception, System.Runtime.Serialization.ISerializable 
[SerializableAttribute()] 
public ref class TwainException : public LeadtoolsException, System.Runtime.InteropServices._Exception, System.Runtime.Serialization.ISerializable   
Remarks

The TwainException class defines a Code property that you can examine to determine what caused the error.

Default messages are implemented for each Code, you can however modify any message through the GetCodeMessage and SetCodeMessage methods.

Example
C#
using Leadtools; 
using Leadtools.Twain; 
 
 
public void _twainSession_AcquirePage(object sender, TwainAcquirePageEventArgs e) 
{ 
   Application.DoEvents(); 
 
   if (e.Image != null) 
      e.Image.Dispose(); 
 
   e.Cancel = false; 
} 
public void TwainExceptionExample(IntPtr 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(); 
   } 
} 
Requirements

Target Platforms

Help Version 22.0.2022.4.5
Products | Support | Contact Us | Intellectual Property Notices
© 1991-2022 LEAD Technologies, Inc. All Rights Reserved.

Leadtools.Twain Assembly

Products | Support | Contact Us | Intellectual Property Notices
© 1991-2022 LEAD Technologies, Inc. All Rights Reserved.