Create PDF interactive form fields

using GemBox.Pdf;
using GemBox.Pdf.Content;

class Program
{
    static void Main()
    {
        // If using the Professional version, put your serial key below.
        ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        using (var document = new PdfDocument())
        {
            var page = document.Pages.Add();

            PdfSize pageSize = page.Size, fieldSize = new PdfSize(150, 20);
            double x = pageSize.Width / 2 - 100, xLabel = x - 5, xField = x + 5, y = pageSize.Height - 50;

            using (var headerText = new PdfFormattedText())
            {
                headerText.Font = new PdfFont("Helvetica", 12);
                headerText.FontWeight = PdfFontWeight.Bold;
                headerText.MaxTextWidth = pageSize.Width - 100;
                headerText.AppendLine("PDF Form Example");
                headerText.FontWeight = PdfFontWeight.Normal;
                headerText.Append("This is an example of a user fillable PDF form. The fields of this form have been selected to demonstrate as many as possible of the common entry fields.");
                page.Content.DrawText(headerText, new PdfPoint(50, y - headerText.Height));
                y -= 100;
            }

            using (var labelText = new PdfFormattedText())
            {
                labelText.TextAlignment = PdfTextAlignment.Right;
                labelText.Font = new PdfFont("Helvetica", 12);

                // Add a 'Full name' label and a 'FullName' text field.
                labelText.Append("Full name:");
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelText.Height));
                var fullNameField = document.Form.Fields.AddText(page, xField, y - (labelText.Height + fieldSize.Height) / 2, fieldSize.Width, fieldSize.Height);
                fullNameField.Name = "FullName";

                // Add an 'ID' label and an 'ID' text field that accepts at most 10 characters that are evenly spaced between vertical, comb-like, lines.
                y -= 40;
                labelText.Clear();
                labelText.Append("ID:");
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelText.Height));
                var idField = document.Form.Fields.AddText(page, xField, y - (labelText.Height + fieldSize.Height) / 2, fieldSize.Width, fieldSize.Height);
                idField.Name = "ID";
                idField.CombOfCharacters = 10;
                // Make vertical comb-like lines, colored black.
                idField.Appearance.BorderColor = PdfColors.Black;

                // Add 'Gender', 'Male', and 'Female' labels and two 'Gender' radio button fields with the choices 'Male' and 'Female'.
                y -= 40;
                labelText.Clear();
                labelText.Append("Gender:");
                var labelTextHeight = labelText.Height;
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelTextHeight));
                document.Form.Fields.NewRadioButtonName = "Gender";
                var genderMaleField = document.Form.Fields.AddRadioButton(page, xField, y - (labelTextHeight + fieldSize.Height) / 2, fieldSize.Height, fieldSize.Height);
                genderMaleField.Choice = "Male";
                labelText.Clear();
                labelText.TextAlignment = PdfTextAlignment.Left;
                labelText.Append("Male");
                page.Content.DrawText(labelText, new PdfPoint(xField + fieldSize.Height + 5, y - (labelTextHeight + labelText.Height) / 2));
                var genderFemaleField = document.Form.Fields.AddRadioButton(page, xField + fieldSize.Width / 2, y - (labelTextHeight + fieldSize.Height) / 2, fieldSize.Height, fieldSize.Height);
                genderFemaleField.Choice = "Female";
                labelText.Clear();
                labelText.Append("Female");
                page.Content.DrawText(labelText, new PdfPoint(xField + fieldSize.Width / 2 + fieldSize.Height + 5, y - (labelTextHeight + labelText.Height) / 2));

                // Add a 'Married' label and a 'Married' check box field with the export value 'Yes'.
                y -= 40;
                labelText.Clear();
                labelText.TextAlignment = PdfTextAlignment.Right;
                labelText.Append("Married:");
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelText.Height));
                var marriedField = document.Form.Fields.AddCheckBox(page, xField, y - (labelText.Height + fieldSize.Height) / 2, fieldSize.Height, fieldSize.Height);
                marriedField.Name = "Married";
                marriedField.ExportValue = "Yes";

                // Add a 'City' label and a 'City' combo box field that contains several predefined values and allows the user to enter a custom value.
                y -= 40;
                labelText.Clear();
                labelText.Append("City:");
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelText.Height));
                var cityField = document.Form.Fields.AddDropdown(page, xField, y - (labelText.Height + fieldSize.Height) / 2, fieldSize.Width, fieldSize.Height);
                cityField.Name = "City";
                cityField.Items.Add("New York");
                cityField.Items.Add("London");
                cityField.Items.Add("Berlin");
                cityField.Items.Add("Paris");
                cityField.Items.Add("Rome");
                cityField.AllowCustomText = true;

                // Add a 'Language' label and a 'Language' list box field that contains several predefined values and allows the user to select more than one value.
                y -= 40;
                labelText.Clear();
                labelText.Append("Language:");
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelText.Height));
                var languageField = document.Form.Fields.AddListBox(page, xField, y - 60, fieldSize.Width, 60);
                languageField.Name = "Language";
                languageField.Items.Add("English");
                languageField.Items.Add("German");
                languageField.Items.Add("French");
                languageField.Items.Add("Italian");
                languageField.MultipleSelection = true;

                // Add a 'Notes' label and a 'Notes' text field that may contain multiple lines of text.
                y -= 80;
                labelText.Clear();
                labelText.Append("Notes:");
                page.Content.DrawText(labelText, new PdfPoint(xLabel, y - labelText.Height));
                var notesField = document.Form.Fields.AddText(page, xField, y - 80, fieldSize.Width, 80);
                notesField.Name = "Notes";
                notesField.MultiLine = true;

                // Add a 'ResetButton' button field with an action that resets all form fields to their default values.
                y -= 100;
                var resetField = document.Form.Fields.AddButton(page, xField, y - fieldSize.Height, fieldSize.Width, fieldSize.Height);
                resetField.Name = "ResetButton";
                resetField.Appearance.Label = "Reset";
                resetField.Actions.AddResetForm();
            }

            document.Save("Form.pdf");
        }
    }
}