Enhancing PDF Format in C# and .NET

Formatting the contents of PDF documents is an important task when working with PDF files in C# and .NET. In this article, we will look at how you can fill in and format the contents of PDF documents using the SautinSoft.Pdf .NET library.

Using this SDK, you can easily fill out forms and format PDF documents in C# and .NET by following a few steps.

  1. Add SautinSoft.PDF from NuGet.
  2. Create a new PDF document.
  3. Add text with formatting.
  4. Create a five-pointed star and make the outline red (in the DeviceRGB color space).
  5. Clone a five-pointed star and create a yellow outline (in the DeviceCMYK color space).
  6. Save the document.

Output result:

Complete code

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

class Program
    /// <summary>
    /// Filling
    /// </summary>
    /// <remarks>
    /// Details: https://sautinsoft.com/products/pdf/help/net/developer-guide/pdf-content-formatting-filling.php
    /// </remarks>
    static void Main()
        // 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();

            // PdfFormattedText currently supports just Device color spaces (DeviceGray, DeviceRGB, and DeviceCMYK).
            using (var formattedText = new PdfFormattedText())
                formattedText.Font = new PdfFont("Helvetica", 100);

                // Make the text fill black (in DeviceGray color space) and 50% opaque.
                formattedText.Color = PdfColor.FromGray(0);
                // In PDF, opacity is defined separately from the color.
                formattedText.Opacity = 0.5;
                formattedText.Append("Hello world!");

                page.Content.DrawText(formattedText, new PdfPoint(50, 700));

            // Path filled with non-zero winding number rule.
            var path = page.Content.Elements.AddPath();
            var center = new PdfPoint(300, 500);
            double radius = 150, cos1 = Math.Cos(Math.PI / 10), sin1 = Math.Sin(Math.PI / 10), cos2 = Math.Cos(Math.PI / 5), sin2 = Math.Sin(Math.PI / 5);
            // Create a five-point star.
            BeginSubpath(center.X - sin2 * radius, center.Y - cos2 * radius). // Start from the point in the bottom-left corner.
            LineTo(center.X + cos1 * radius, center.Y + sin1 * radius). // Continue to the point in the upper-right corner.
            LineTo(center.X - cos1 * radius, center.Y + sin1 * radius). // Continue to the point in the upper-left corner.
            LineTo(center.X + sin2 * radius, center.Y - cos2 * radius). // Continue to the point in the bottom-right corner.
            LineTo(center.X, center.Y + radius). // Continue to the point in the upper-center.
            CloseSubpath(); // End with the starting point.
            var format = path.Format;
            format.Fill.IsApplied = true;
            format.Fill.Rule = PdfFillRule.NonzeroWindingNumber;
            // Make the path fill red (in DeviceRGB color space) and 40% opaque.
            format.Fill.Color = PdfColor.FromRgb(1, 0, 0);
            format.Fill.Opacity = 0.4;

            // Path filled with even-odd rule.
            path = page.Content.Elements.AddClone(path);
            path.Subpaths.Transform(PdfMatrix.CreateTranslation(0, -300));
            format = path.Format;
            format.Fill.IsApplied = true;
            format.Fill.Rule = PdfFillRule.EvenOdd;
            // Make the path fill yellow (in DeviceCMYK color space) and 60% opaque.
            format.Fill.Color = PdfColor.FromCmyk(0, 0, 1, 0);
            format.Fill.Opacity = 0.6;


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


If you need a new code example or have a question: email us at support@sautinsoft.com or ask at Online Chat (right-bottom corner of this page) or use the Form below:

Questions and suggestions from you are always welcome!

We are developing .Net components since 2002. We know PDF, DOCX, RTF, HTML, XLSX and Images formats. If you need any assistance with creating, modifying or converting documents in various formats, we can help you. We will write any code example for you absolutely free.