public class PdfTextFormFieldFacade :
    PdfFormFieldFacade<PdfTextWidgetFacade, PdfTextFormField>

Public Class PdfTextFormFieldFacade
    Inherits PdfFormFieldFacade(Of PdfTextWidgetFacade, PdfTextFormField)

using (PdfDocumentProcessor pdfDocumentProcessor = new PdfDocumentProcessor())
{
    pdfDocumentProcessor.LoadDocument("Documents//FormDemo.pdf");

    PdfDocumentFacade documentFacade = pdfDocumentProcessor.DocumentFacade;
    PdfAcroFormFacade acroForm = documentFacade.AcroForm;
    PdfTextFormFieldFacade visaField = acroForm.GetTextFormField("VisaNo");

    //Divide field text into equally spaced positions:
    visaField.InputType = PdfTextFieldInputType.Comb;
    visaField.Multiline = false;

    //Limit the number of inserted characters:
    visaField.MaxLength = 8;

    //Enable multiline text in the text field:
    PdfTextFormFieldFacade addressField = acroForm.GetTextFormField("Address");
    addressField.Multiline = true;

    addressField.Scrollable = true;
    addressField.SpellCheck = false;
}

Using pdfDocumentProcessor As New PdfDocumentProcessor()
  pdfDocumentProcessor.LoadDocument("Documents//FormDemo.pdf")

  Dim documentFacade As PdfDocumentFacade = pdfDocumentProcessor.DocumentFacade
  Dim acroForm As PdfAcroFormFacade = documentFacade.AcroForm
  Dim visaField As PdfTextFormFieldFacade = acroForm.GetTextFormField("VisaNo")

  'Divide field text into equally spaced positions:
  visaField.InputType = PdfTextFieldInputType.Comb
  visaField.Multiline = False

  'Limit the number of inserted characters:
  visaField.MaxLength = 8

  'Enable multiline text in the text field:
  Dim addressField As PdfTextFormFieldFacade = acroForm.GetTextFormField("Address")
  addressField.Multiline = True

  addressField.Scrollable = True
  addressField.SpellCheck = False
End Using

using (PdfDocumentProcessor pdfDocumentProcessor = new PdfDocumentProcessor())
{
    pdfDocumentProcessor.LoadDocument("Documents//FormDemo.pdf");

    PdfDocumentFacade documentFacade = pdfDocumentProcessor.DocumentFacade;
    PdfAcroFormFacade acroForm = documentFacade.AcroForm;

    //Change all text form fields' color settings:
    var fields = acroForm.GetFields();
    foreach (PdfFormFieldFacade field in fields)
    {
        if (field.Type == PdfFormFieldType.Text)
        {
            ChangeFormFieldColor(field);
        }
    }
}

  private static void ChangeFormFieldColor(PdfFormFieldFacade field)
  {
      foreach (PdfWidgetFacade pdfWidget in field)
      {
          //Change color and border settings

          pdfWidget.BorderWidth = 1;
          pdfWidget.BackgroundColor = new PdfRGBColor(0.81, 0.81, 0.81);
          pdfWidget.BorderColor = new PdfRGBColor(0.47, 0.44, 0.67);
          pdfWidget.FontColor = new PdfRGBColor(0.34, 0.25, 0.36);

          //Change border style:
          pdfWidget.BorderStyle = PdfBorderStyle.Underline;
      }
  }

Using pdfDocumentProcessor As New PdfDocumentProcessor()
  pdfDocumentProcessor.LoadDocument("Documents//FormDemo.pdf")

  Dim documentFacade As PdfDocumentFacade = pdfDocumentProcessor.DocumentFacade
  Dim acroForm As PdfAcroFormFacade = documentFacade.AcroForm

  'Change all text form fields' color settings:
  Dim fields = acroForm.GetFields()
  For Each field As PdfFormFieldFacade In fields
    If field.Type = PdfFormFieldType.Text Then
      ChangeFormFieldColor(field)
    End If
  Next field
End Using

  private static void ChangeFormFieldColor(PdfFormFieldFacade field)
    For Each pdfWidget As PdfWidgetFacade In field
      'Change color and border settings

      pdfWidget.BorderWidth = 1
      pdfWidget.BackgroundColor = New PdfRGBColor(0.81, 0.81, 0.81)
      pdfWidget.BorderColor = New PdfRGBColor(0.47, 0.44, 0.67)
      pdfWidget.FontColor = New PdfRGBColor(0.34, 0.25, 0.36)

      'Change border style:
      pdfWidget.BorderStyle = PdfBorderStyle.Underline
    Next pdfWidget