//// This code is part of Document Solutions for PDF .NET demos.// Copyright (c) MESCIUS inc. All rights reserved.//using System;using System.IO;using System.Drawing;using GrapeCity.Documents.Pdf;using GrapeCity.Documents.Pdf.AcroForms;using GrapeCity.Documents.Text;using System.Security.Cryptography.X509Certificates;
namespace DsPdfWeb.Demos{    // This sample demonstrates how to create and sign a PDF with a .pfx file,    // using a SignatureField.    // The sample then loads the signed file back into another GcPdfDocument instance    // and verifies the signature.    // See also VisualSignature which is similar but adds a visual representation    // of the signature.    public class SignDoc    {        public int CreatePDF(Stream stream)        {            var doc = new GcPdfDocument();            var page = doc.NewPage();            var tf = new TextFormat() { Font = StandardFonts.Times, FontSize = 14 };            page.Graphics.DrawString("Hello, World!\n" +                "Signed by DsPdfWeb SignDoc sample.",                tf, new PointF(72, 72));
            // Init a test certificate:            var pfxPath = Path.Combine("Resources", "Misc", "DsPdfTest.pfx");            var cert = new X509Certificate2(File.ReadAllBytes(pfxPath), "qq",                X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable);            var sp = new SignatureProperties()            {                SignatureBuilder = new Pkcs7SignatureBuilder()                {                    CertificateChain = new X509Certificate2[] { cert }                },                Location = "DsPdfWeb Demo Browser",                SignerName = "DsPdfWeb",                SigningDateTime = Common.Util.TimeNow(),            };
            // Init a signature field to hold the signature:            var sf = new SignatureField();            sf.Widget.Rect = new RectangleF(72, 72 * 2, 72 * 4, 36);            sf.Widget.Page = page;            sf.Widget.BackColor = Color.LightSeaGreen;            sf.Widget.DefaultAppearance.Font = StandardFonts.Helvetica;            sf.Widget.ButtonAppearance.Caption = $"Signer: {sp.SignerName}\r\nLocation: {sp.Location}";            // Add the signature field to the document:            doc.AcroForm.Fields.Add(sf);            // Connect the signature field and signature props:            sp.SignatureField = sf;
            // Sign and save the document:            // NOTES:            // - Signing and saving is an atomic operation, the two cannot be separated.            // - The stream passed to the Sign() method must be readable.            doc.Sign(sp, stream);
            // Rewind the stream to read the document just created             // into another GcPdfDocument and verify the signature:            stream.Seek(0, SeekOrigin.Begin);            var doc2 = new GcPdfDocument();            doc2.Load(stream);            SignatureField sf2 = (SignatureField)doc2.AcroForm.Fields[0];            if (!sf2.Value.VerifySignatureValue())                throw new Exception("Failed to verify the signature");
            // Done (the generated and signed document has already been saved to 'stream').            return doc.Pages.Count;        }    }}