//// 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.Security;using GrapeCity.Documents.Text;
namespace DsPdfWeb.Demos{    // This example shows how to load a password protected PDF and change its metadata.    // Keep in mind that in some cases metadata in a PDF may also be encrypted, in which case    // accessing it without the password is impossible.    // For reference, the loaded PDF is protected with the owner password 'owner' and user password 'user'.    public class NoPassSetMetadata    {        public int CreatePDF(Stream stream)        {            using var fs = File.OpenRead(Path.Combine("Resources", "PDFs", "Wetlands-password-user.pdf"));            // Set up DecryptionOptions to allow loading password protected PDFs without password:            var dopt = new DecryptionOptions() { ThrowExceptionIfInvalidPassword = false };            var docSrc = new GcPdfDocument();            docSrc.Load(fs, dopt);
            // All security handlers before StandardSecurityHandlerRev4 always encrypted metadata,            // the StandardSecurityHandlerRev4 has EncryptMetadata property which we need to check:            bool metadataIsEncrypted = true;            if (docSrc.Security.EncryptHandler is StandardSecurityHandlerRev4 ssh)                metadataIsEncrypted = ssh.EncryptMetadata;            // In the PDf used by this demo the metadata is not encrypted:            if (metadataIsEncrypted)                throw new Exception("Set PDF Metadata demo: Unexpected error.");
            Metadata m = docSrc.Metadata;            // Save original metadata so we can compare the results:            var origTitle = m.Title;            var origCreatorTool = m.CreatorTool;            var origModifyDate = m.ModifyDate;            // Change some metadata:            m.Title = "Set PDF Metadata Demo";            m.CreatorTool = "DsPdf Demo Browser";            m.ModifyDate = Common.Util.TimeNow();
            // We save the modified password protected document to a temp file,            // load it again (also without password), read the (modified) metadata            // and display it in the resulting PDF:            var fn = Path.GetTempFileName();            {                docSrc.Save(fn);
                using var fsTemp = File.OpenRead(fn);                var docTemp = new GcPdfDocument();                docTemp.Load(fsTemp, dopt);
                // The PDF to hold the results:                var doc = new GcPdfDocument();                var page = doc.NewPage();                // Set up a TextLayout to format the results:                var tl = page.Graphics.CreateTextLayout();                tl.DefaultFormat.Font = StandardFonts.Courier;                tl.DefaultFormat.FontSize = 14;                tl.MaxWidth = doc.PageSize.Width;                tl.MaxHeight = doc.PageSize.Height;                tl.MarginAll = tl.Resolution;                var captionFmt = new TextFormat(tl.DefaultFormat) { Font = StandardFonts.CourierBold, FontSize = tl.DefaultFormat.FontSize + 2 };
                if (docTemp.Security.EncryptHandler is StandardSecurityHandlerRev4 sshTemp)                    metadataIsEncrypted = sshTemp.EncryptMetadata;                if (metadataIsEncrypted)                    throw new Exception("Set PDF Metadata demo: Unexpected error.");
                // Render the results:                Metadata mTemp = docTemp.Metadata;                tl.AppendLine("Modified metadata in a password protected PDF:", captionFmt);                tl.AppendLine($"\nTitle", captionFmt);                tl.AppendLine($"Was '{origTitle}', now '{mTemp.Title}'");                tl.AppendLine($"\nCreatorTool", captionFmt);                tl.AppendLine($"Was '{origCreatorTool}', now '{mTemp.CreatorTool}'");                tl.AppendLine($"\nModifyDate", captionFmt);                var origModifyDateStr = origModifyDate.HasValue ? origModifyDate.Value.ToUniversalTime().ToString("R") : string.Empty;                var newModifyDateStr = mTemp.ModifyDate.HasValue ? mTemp.ModifyDate.Value.ToUniversalTime().ToString("R") : string.Empty;                tl.AppendLine($"Was '{origModifyDateStr}', now '{newModifyDateStr}'");                tl.PerformLayout(true);                page.Graphics.DrawTextLayout(tl, PointF.Empty);                doc.Save(stream);            }            File.Delete(fn);
            // Done:            return 1;        }    }}