Interactive PDF Form Fields Generation using C# and .NET

An interactive form, sometimes referred to as an AcroForm, is a collection of fields for gathering information interactively from the user. A PDF document may contain an arbitrary number of fields on any combination of pages, all of which together constitute a single global interactive form spanning the entire document.

An interactive form in PDF .Net is represented by a PdfInteractiveForm class and can be accessed via the Form property of the PDF .Net class.

PDF .Net supports creating various types of form fields, such as text, radio button, check box, combo box, list box, signature, and button, as shown in the following example.

Complete code

using System;
using System.IO;
using SautinSoft;
using SautinSoft.Pdf;
using SautinSoft.Pdf.Content;

namespace Sample
{
    class Sample
    {
        /// <summary>
        /// Create PDF interactive form fields.
        /// </summary>
        /// <remarks>
        /// Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/create-interactive-form.php
        /// </remarks>
        static void Main(string[] args)
        {
            // Before starting this example, please get a free 100-day trial key:
            // https://sautinsoft.com/start-for-free/

            // Apply the key here:
            // PdfDocument.SetLicense("...");

            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())
                {
                    // Draw header text.
                    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";
                    genderMaleField.Name = "Gender";
                    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";
                    genderFemaleField.Name = "Gender";
                    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();
                }
                // Save PDF Document.
                document.Save("Form.pdf");
            }

            System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo("Form.pdf") { UseShellExecute = true });
        }
    }
}

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