Twain Duplex Tutorial

Take the following steps to start a project:

  1. Start Visual Studio.

  2. Choose File->New->Project… from the menu.

  3. 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.

  4. 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.

  5. 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.

  6. 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
  7. 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:

    VB
    Imports Leadtools 
    Imports Leadtools.Twain 
    Imports Leadtools.Codecs 
    Imports Leadtools.WinForms 
    C#
    using Leadtools; 
    using Leadtools.Twain; 
    using Leadtools.Codecs; 
    using Leadtools.WinForms; 

  8. Declare the following private variable:

    VB
    Private WithEvents twnSession As TwainSession 
    C#
    private TwainSession twnSession; 

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

    VB
    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    
    C#
    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); 
       } 
    } 

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

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

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

    VB
    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 
    C#
    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); 
    } 

  12. Build, and Run the program to test it.
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