虚拟扫描程序（TWAIN）无法在C＃（WPF）中工作

Question

这是关于TWAINdotNet库。我花了24小时尝试在C＃/ WPF / VS2010中进行基本的虚拟扫描程序实验。我已经从http://sourceforge.net/projects/twain-samples/files/下载并安装了虚拟扫描仪驱动程序，它在可用的TWAIN数据源列表中显示得很好。有趣的是，此页面上提供的示例应用程序也适用于此驱动程序。只有当我尝试通过C＃/ WPF使用它时才会出现问题。

具体来说，使用DsUserInterface调用Message.EnableDS对上帝失败了 - 知道是什么原因。它在所有情况下都失败了我是否要求它显示UI。同样，DsImageLayout调用也会在尝试设置扫描区域时导致失败。最后但并非最不重要的是，尝试将测量单位设置为英寸（或其他）也不会生效。呼叫不会失败，但之前的值保持不变。

以下是我可能做错事的代码：

public partial class MainWindow : Window
{
    TwainDotNet.Wpf.WpfWindowMessageHook mTwnHook;
    TwainDotNet.Twain mTWN;
    TwainDotNet.ScanSettings setting = new TwainDotNet.ScanSettings();

    public MainWindow()
    {
        InitializeComponent();
    }

    private void btnScan_Click(object sender, RoutedEventArgs e)
    {
        InitializeTWAIN();

        mTWN.ScanningComplete += twn_ScanningComplete;
        mTWN.TransferImage += twn_TransferImage;

        mTWN.StartScanning(setting);            
    }

    private void InitializeTWAIN()
    {
        mTwnHook = new TwainDotNet.Wpf.WpfWindowMessageHook(this);
        mTWN = new TwainDotNet.Twain(mTwnHook);

        setting.UseAutoFeeder = true;
        setting.UseDocumentFeeder = true;
        setting.UseDuplex = true;
        setting.TransferCount = 1;

        setting.Page = new TwainDotNet.PageSettings() 
        { 
                    Orientation = TwainDotNet.TwainNative.Orientation.Auto, 
                    Size = TwainDotNet.TwainNative.PageType.UsLetter 
        };

        setting.Area = new TwainDotNet.AreaSettings(TwainDotNet.TwainNative.Units.Millimeters, 0f, 0f, 279.4f, 215.9f);
        setting.Resolution = new TwainDotNet.ResolutionSettings() 
        { 
                    ColourSetting = TwainDotNet.ColourSetting.Colour, 
                    Dpi = 100 
        };

        setting.ShouldTransferAllPages = true;
        setting.ShowTwainUI = false;
    }

    void twn_TransferImage(object sender, TwainDotNet.TransferImageEventArgs e)
    {
      //save  image
    }

    void twn_ScanningComplete(object sender, TwainDotNet.ScanningCompleteEventArgs e)
    {
        if (e.Exception != null)
            MessageBox.Show(e.Exception.Message);
    }
}