Twain Duplex Tutorial

Take the following steps to start a project:

Start Visual Studio .NET.
Choose File->New->Project… from the menu.
In the New Project dialog box, choose either "Visual C# Projects" or "Visual Basic Projects" in the Projects Type List, and choose "Windows Application " in the Templates List.
Type the project name as "GetFastTwainScan" 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 "\LEAD Technologies\LEADTOOLS 16.5\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 a 1 instance of Button control to the top of the form and set the following properties for them:

Text Name
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:
[Visual Basic]
```
Imports Leadtools
Imports Leadtools.Twain
Imports Leadtools.Codecs
Imports Leadtools.WinForms
```
[C#]
```
using Leadtools;
using Leadtools.Twain;
using Leadtools.Codecs;
using Leadtools.WinForms;
```

Declare the following private variable:

[Visual Basic]


Private WithEvents twnSession As TwainSession

[C#]


private TwainSession twnSession;

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

[Visual Basic]


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.
      RasterSupport.Unlock(RasterSupportType.Document, "TestKey")

      twnSession = new TwainSession
      twnSession.Startup(Me, "LEAD Technologies, Inc.", "LEAD Twain .NET", "Version 14", "LEADTools Twain test sample", 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.
      RasterSupport.Unlock(RasterSupportType.Document, "TestKey");

      twnSession = new TwainSession();
      twnSession.Startup(this, "LEAD Technologies, Inc.", "LEAD Twain .NET", "Version 14", "LEADTools Twain test sample", TwainStartupFlags.None);
   }
   catch (Exception ex)
   {
      MessageBox.Show(this, ex.Message);
   }
}

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

[Visual Basic]


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);
   }
}

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

[Visual Basic]


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);
}

Build, and Run the program to test it.

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Twain Duplex Tutorial

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