Twain Duplex Tutorial

Take the following steps to start a project:

Start Visual Studio.
Choose File->New->Project… from the menu.
In the New Project dialog box, choose either "Visual C# Projects" or "VB Projects" in the Projects Type List, and choose "Windows Application" in the Templates List.
Type the project name as "TwainDuplex" in the Project Name field, and then choose OK. If desired, type a new location for your project or select a directory using the Browse button, and then choose OK.
In the "Solution Explorer" window, right-click on the "References" folder, and select "Add Reference…" from the context menu. In the "Add Reference" dialog box, select the ".NET" tab and browse to Leadtools For .NET "<LEADTOOLS_INSTALLDIR>\Bin\Dotnet\Win32" folder and select the following DLLs:
- Leadtools.dll
- Leadtools.Twain.dll
- Leadtools.Codecs.dll
- Leadtools.WinForms.dll
Click the Select button and then press the OK button to add the above DLLs to the application.
Go to the toolbox (View->Toolbox) and Drag and drop an instance of Button control to the top of the form and set the following properties for them:

Text Name

Acquire buttonAcquire

Switch to Form1 code view (right-click Form1 in the solution explorer then select View Code ) and add the following lines at the beginning of the file:

Imports Leadtools 
Imports Leadtools.Twain 
Imports Leadtools.Codecs 
Imports Leadtools.WinForms

using Leadtools; 
using Leadtools.Twain; 
using Leadtools.Codecs; 
using Leadtools.WinForms;

Declare the following private variable:

Private WithEvents twnSession As TwainSession

private TwainSession twnSession;

Add an event handler to the Form1 Load event and code it as follows:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
   Try 
      ' Unlock Document support. 
      ' Note that this is a sample key, which will not work in your toolkit. 
      Dim MY_LICENSE_FILE As String = "d:\temp\TestLic.lic" 
      Dim MY_DEVELOPER_KEY As String = "xyz123abc" 
      RasterSupport.SetLicense(MY_LICENSE_FILE, MY_DEVELOPER_KEY) 
      twnSession = new TwainSession 
      twnSession.Startup(Me.Handle, "manufacturer", "productFamily", "version", "application", TwainStartupFlags.None) 
   Catch ex As Exception 
      MessageBox.Show(ex.Message) 
   End Try 
End Sub

private void Form1_Load(object sender, System.EventArgs e) 
{ 
   try 
   { 
      // Unlock Document support. 
      // Note that this is a sample key, which will not work in your toolkit. 
      string MY_LICENSE_FILE = "d:\\temp\\TestLic.lic"; 
      string MY_DEVELOPER_KEY = "xyz123abc"; 
      RasterSupport.SetLicense(MY_LICENSE_FILE, MY_DEVELOPER_KEY); 
      twnSession = new TwainSession(); 
      twnSession.Startup(this.Handle, "manufacturer", "productFamily", "version", "application", TwainStartupFlags.None); 
   } 
   catch (Exception ex) 
   { 
      MessageBox.Show(this, ex.Message); 
   } 
}

Add an event handler to the Form1 Closing event and code it as follows:

Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing 
   Try 
      twnSession.Shutdown() 
   Catch ex As Exception 
      MessageBox.Show(ex.Message) 
   End Try 
End Sub

private void Form1_FormClosing(object sender, FormClosingEventArgs e) 
{ 
   try 
   { 
      twnSession.Shutdown(); 
   } 
   catch (Exception ex) 
   { 
      MessageBox.Show(this, ex.Message); 
   } 
}

Add an event handler to the buttonAcquire Click event and code it as follows:

Private Sub buttonAcquire_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles buttonAcquire.Click 
   Dim twainCap As TwainCapability 
   twnSession.SelectSource(String.Empty) 
   Try 
   twainCap = twnSession.GetCapability(TwainCapabilityType.Duplex, TwainGetCapabilityMode.GetValues) 
      If Not IsNothing(twainCap) Then 
         ' check if the selected driver supports duplex capability 
         If (twainCap.OneValueCapability.ItemType <> TwainItemType.Uint16) Then 
            twnSession.Shutdown() 
            Return 
         End If 
         Dim item As TwainCapabilityValue = CType(twainCap.OneValueCapability.Value, TwainCapabilityValue) 
         Select Case item 
            Case TwainCapabilityValue.DuplexNone 
               MessageBox.Show(Me, "Duplex capability is not supported in the selected driver") 
            Case TwainCapabilityValue.DuplexOnePassDuplex 
               MessageBox.Show(Me, "1 Pass Duplex capability is supported in the selected driver") 
            Case TwainCapabilityValue.DuplexTwoPassDuplex 
               MessageBox.Show(Me, "2 Pass Duplex capability is supported in the selected driver") 
         End Select 
         ' make sure the duplex capability is enabled 
         If item <> TwainCapabilityValue.DuplexNone Then 
            Dim enable As Boolean = True 
            twainCap.Information.Type = TwainCapabilityType.DuplexEnabled 
            twainCap.Information.ContainerType = TwainContainerType.OneValue 
            twainCap.OneValueCapability.ItemType = TwainItemType.Bool 
            twainCap.OneValueCapability.Value = CType(enable, Object) 
            twnSession.SetCapability(twainCap, TwainSetCapabilityMode.Set) 
            MessageBox.Show(Me, "The duplex capability is enabled") 
         End If 
      End If 
   Catch ex As Exception 
      MessageBox.Show(Me, ex.Message) 
   End Try 
   ' try to acquire pages using duplex capability 
   twnSession.Acquire(TwainUserInterfaceFlags.Show Or TwainUserInterfaceFlags.Modal) 
End Sub

private void buttonAcquire_Click(object sender, System.EventArgs e) 
{ 
   TwainCapability twainCap; 
   twnSession.SelectSource(string.Empty); 
   try 
   { 
      twainCap = twnSession.GetCapability(TwainCapabilityType.Duplex, TwainGetCapabilityMode.GetValues); 
      if (twainCap != null) 
      { 
         //  check if the selected driver supports duplex capability 
         if (twainCap.OneValueCapability.ItemType != TwainItemType.Uint16) 
         { 
            twnSession.Shutdown(); 
            return; 
         } 
         TwainCapabilityValue item = (TwainCapabilityValue)twainCap.OneValueCapability.Value; 
         switch (item) 
         { 
            case TwainCapabilityValue.DuplexNone: 
               MessageBox.Show(this, "Duplex capability is not supported in the selected driver"); 
               break; 
            case TwainCapabilityValue.DuplexOnePassDuplex: 
               MessageBox.Show(this, "1 Pass Duplex capability is supported in the selected driver"); 
               break; 
            case TwainCapabilityValue.DuplexTwoPassDuplex: 
               MessageBox.Show(this, "2 Pass Duplex capability is supported in the selected driver"); 
               break; 
         } 
         //  make sure the duplex capability is enabled 
         if (item != TwainCapabilityValue.DuplexNone) 
         { 
            bool enable = true; 
            twainCap.Information.Type = TwainCapabilityType.DuplexEnabled; 
            twainCap.Information.ContainerType = TwainContainerType.OneValue; 
            twainCap.OneValueCapability.ItemType = TwainItemType.Bool; 
            twainCap.OneValueCapability.Value = enable; 
            twnSession.SetCapability(twainCap, TwainSetCapabilityMode.Set); 
            MessageBox.Show(this, "The duplex capability is enabled"); 
         } 
      } 
   } 
   catch (Exception ex) 
   { 
      MessageBox.Show(this, ex.Message); 
   } 
   //  try to acquire pages using duplex capability 
   twnSession.Acquire(TwainUserInterfaceFlags.Show |   TwainUserInterfaceFlags.Modal); 
}

Build, and Run the program to test it.

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Help Version 20.0.2020.4.3

Text	Name
Acquire	buttonAcquire