本次经验内容分享C#程序中跗柿椁焚如何给PDF文档添加可视化数字签名的方法。即在PDF中的指定页面位置添加签名，包括前面图片，文字等信息。
工具/原料
VisualStudio2017
Windows10
.netframework4.6.1
PDF类库：Spire.PDFfor.NET
方法/步骤
1、在VS中通过Nuget安装Spire.PDF,步骤如图：
2、安装结果：
3、C#代码：usingSpire.Pd酆璁冻嘌f;usingSpire.Pdf.Graphics;usingSp足毂忍珩ire.Pdf.Interactive.DigitalSignatures;usingSystem.Drawing;usingSystem.Security.Cryptography.X509Certificates;namespaceVisibleDigitalSignature{classProgram{staticvoidMain(string[]args){//加载PDF测试文档PdfDocumentpdf=newPdfDocument();pdf.LoadFromFile("test.pdf");//获取PDF文档中的第5页PdfPageBasepage=pdf.Pages[4];//在页面中的指定位置添加可视化签名X509Certificate2x509=newX509Certificate2("cer.pfx","e-iceblue");PdfOrdinarySignatureMakersignatureMaker=newPdfOrdinarySignatureMaker(pdf,x509);IPdfSignatureAppearancesignatureAppearance=newPdfCustomSignatureAppearance();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();}publicclassPdfCustomSignatureAppearance:IPdfSignatureAppearance{publicvoidGenerate(PdfCanvasg){floatfontSize=15;PdfTrueTypeFontfont=newPdfTrueTypeFont(newFont("Arial",fontSize),true);floatlineHeight=fontSize;g.DrawString("SignHere:",font,PdfBrushes.Black,newPointF(0,0));g.DrawImage(PdfImage.FromFile("sign.png"),newPointF(20,20));}}}}
4、数字签名效果：
