Introduction

public static void AddFormFields()
{
  Console.WriteLine( "=== ADD FORM FIELDS ===" );
  var outputFileName = "AddFormFields.pdf";
  var outputPath = FormFieldsSample.FormFieldsSampleOutputDirectory + outputFileName;

  using( var pdfoutput = PdfDocument.Create( outputPath ) )
  {
    // Get first page of document.
    var page = pdfoutput.Pages[ 0 ];

    // Add Title.
    var titleStyle = TextStyle.WithFont( pdfoutput.Fonts.GetStandardFont( StandardFontType.Helvetica ), 15d );
    page.AddParagraph( "Add FormFields", titleStyle, new ParagraphStyle( ParagraphHorizontalAlignment.Center ) );

    // Define a font for text to add.
    var formFieldFont = pdfoutput.Fonts.GetStandardFont( StandardFontType.CourierBoldOblique );

    // Add TextBoxFormField.
    page.AddText( "TextBox:", new Point( 50, 100 ) );
    var textBoxField = new TextBoxFormField( "John Doe", new Rectangle( 125, 92, 120, 22 ), TextStyle.WithFontAndColor( formFieldFont, 13d, Color.Blue ) );
    textBoxField.Border.Color = Color.Black;
    textBoxField.Border.Width = 2;
    page.FormFields.Add( textBoxField );

    // Add NumberFormField.
    page.AddText( "Number:", new Point( 50, 130 ) );
    var numberField = new NumberFormField( 32.66d, new Rectangle( 125, 122, 120, 22 ), TextStyle.WithFontAndColor( formFieldFont, 13d, Color.DarkBlue ) )
    {
      CurrencySymbol = "$",
      SymbolLocation = SymbolLocation.BeforeNoSpace,
      DecimalPlaces = 2,
    };
    numberField.Border.Color = Color.Green;
    numberField.Border.Width = 1;
    page.FormFields.Add( numberField );

    // Add DateTimeFormField.
    page.AddText( "DateTime:", new Point( 50, 160 ) );
    var dateTimeField = new DateTimeFormField( new DateTime( 2025, 7, 20 ), new Rectangle( 125, 152, 120, 22 ) )
    {
      Format = "yyyy/MM/dd",
      FillColor = Color.LightGray
    };
    page.FormFields.Add( dateTimeField );

    // Add CheckBoxFormField.
    page.AddText( "CheckBox:", new Point( 50, 190 ) );
    var checkBoxField = new CheckBoxFormField( true, new Rectangle( 125, 182, 20, 20 ) )
    {
      CheckedStyle = CheckBoxFormFieldStyle.Check,
      FillColor = Color.LightCyan,
      TextStyle = TextStyle.WithFontAndColor( formFieldFont, 12d, Color.Red )
    };
    page.FormFields.Add( checkBoxField );


    // Add ComboBoxFormField.
    page.AddText( "CombBox:", new Point( 50, 220 ) );
    var comboBoxItems = new List<ListItem>()
    {
      new ListItem( "First" ),
      new ListItem( "Second" ),
      new ListItem( "Third" ),
      new ListItem( "Fourth" )
    };
    var comboBoxField = new ComboBoxFormField( comboBoxItems, new Rectangle( 125, 212, 120, 22 ) )
    {
      FillColor = Color.Black,
      TextStyle = TextStyle.WithFontAndColor( formFieldFont, 12d, Color.Yellow ),
      SelectedIndex = 1,
      IsEditable = true
    };
    page.FormFields.Add( comboBoxField );

    // Add ListBoxFormField.
    page.AddText( "ListBox:", new Point( 50, 250 ) );
    var listItems = new List<ListItem>()
    {
      new ListItem( "Orange" ),
      new ListItem( "Banana" ),
      new ListItem( "Strawberry" ),
      new ListItem( "Blueberry" ),
      new ListItem( "Grape" ),
      new ListItem( "Pineapple" )
    };
    var listBoxFormFieldFont = pdfoutput.Fonts.GetStandardFont( StandardFontType.Helvetica );
    var listBoxField = new ListBoxFormField( listItems, new Rectangle( 125, 242, 120, 85 ) )
    {
      FillColor = Color.DarkGray,
      TextStyle = TextStyle.WithFontAndColor( listBoxFormFieldFont, 12d, Color.White ),
      IsMultiSelect = true,
      SelectedValues = new List<string>() { "Banana", "Blueberry" }
    };
    page.FormFields.Add( listBoxField );

    // Add RadioButtonsFormField.
    page.AddText( "Radio:", new Point( 50, 350 ) );
    var radioButtons = new List<RadioButtonFormField>()
    {
      new RadioButtonFormField( "Friday", new Rectangle( 125, 342, 20, 20 ) ),
      new RadioButtonFormField( "Saturday", new Rectangle( 125, 367, 20, 20 ) ) { IsChecked = true },
      new RadioButtonFormField( "Sunday", new Rectangle( 125, 392, 20, 20 ) )
    };
    var radioGroupField = new RadioButtonGroupFormField( radioButtons )
    {
      TextStyle = TextStyle.WithFontAndColor( formFieldFont, 13d, Color.LightGreen ),
      FillColor = Color.DeepPink
    };
    page.FormFields.Add( radioGroupField );
    page.AddText( "Friday", new Point( 150, 347 ) );
    page.AddText( "Saturday", new Point( 150, 372 ) );
    page.AddText( "Sunday", new Point( 150, 397 ) );

    // Add SignatureFormField.
    page.AddText( "Signature:", new Point( 50, 430 ) );
    var signatureField = new SignatureFormField( new Rectangle( 125, 422, 120, 22 ) )
    {
      Border = new Border() { Color = Color.Blue, Width = 2 }
    };
    page.FormFields.Add( signatureField );

    // Save the document.
    pdfoutput.Save();
    Console.WriteLine( $"Info exported to path: {outputFileName}" );
  }
}