1、在VS中通过Nuget安装Spire.PDF,步骤如图：
2、安装结果：
3、C# 代码：using Spire.Pd酆璁冻嘌f;using Spire.Pdf.Graphics;using Sp足毂忍珩ire.Pdf.Interactive.DigitalSignatures;using System.Drawing;using System.Security.Cryptography.X509Certificates;namespace VisibleDigitalSignature{ class Program { static void Main(string[] args) { //加载PDF测试文档 PdfDocument pdf = new PdfDocument(); pdf.LoadFromFile("test.pdf"); //获取PDF文档中的第5页 PdfPageBase page = pdf.Pages[4]; //在页面中的指定位置添加可视化签名 X509Certificate2 x509 = new X509Certificate2("cer.pfx", "e-iceblue"); PdfOrdinarySignatureMaker signatureMaker = new PdfOrdinarySignatureMaker(pdf, x509); IPdfSignatureAppearance signatureAppearance = new PdfCustomSignatureAppearance(); signatureMaker.MakeSignature("signName_" , page, page.ActualSize.Width-240,page.ActualSize.Height-200,150,150, signatureAppearance); //保存文档 pdf.SaveToFile("VisibleDigitalSignature.pdf", FileFormat.PDF); System.Diagnostics.Process.Start("VisibleDigitalSignature.pdf"); pdf.Close(); } public class PdfCustomSignatureAppearance : IPdfSignatureAppearance { public void Generate(PdfCanvas g) { float fontSize = 15; PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial", fontSize), true); float lineHeight = fontSize; g.DrawString("Sign Here:", font, PdfBrushes.Black, new PointF(0, 0)); g.DrawImage(PdfImage.FromFile("sign.png"), new PointF(20, 20)); } } }}
4、数字签名效果：
