With PDF .Net, you can add a watermark to PDF from your C# or VB.NET application.
The following example shows how you can easily add a watermark to an existing PDF file.
Complete code
using System;
using System.IO;
using SautinSoft;
using SautinSoft.Pdf;
using SautinSoft.Pdf.Content;
namespace Sample
{
class Sample
{
/// <summary>
/// Watermarks.
/// </summary>
/// <remarks>
/// Details: http://sautinsoft/products/pdf/help/net/developer-guide/watermarks.php
/// </remarks>
static void Main(string[] args)
{
string pdfFile = Path.GetFullPath(@"..\..\..\simple text.pdf");
using (var document = PdfDocument.Load(pdfFile))
{
// Load the watermark from a file.
var image = PdfImage.Load(@"..\..\..\WatermarkImage.png");
foreach (var page in document.Pages)
{
// Make sure the watermark is correctly transformed even if
// the page has a custom crop box origin, is rotated, or has custom units.
var transform = page.Transform;
transform.Invert();
// Center the watermark on the page.
var pageSize = page.Size;
transform.Translate((pageSize.Width - 1) / 2, (pageSize.Height - 1) / 2);
// Calculate the scaling factor so that the watermark fits the page.
var cropBox = page.CropBox;
var scale = Math.Min(cropBox.Width, cropBox.Height);
// Scale the watermark so that it fits the page.
transform.Scale(scale, scale, 0.5, 0.5);
// Draw the centered and scaled watermark.
page.Content.DrawImage(image, transform);
}
document.Save("Watermark Images.pdf");
}
}
}
}
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