// 完毕:
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($"\nModifyDate", captionFmt);
var origModifyDateStr = origModifyDate.HasValue ? origModifyDate.Value.ToString("R") : string.Empty;
var newModifyDateStr = mTemp.ModifyDate.HasValue ? mTemp.ModifyDate.Value.ToString("R") : string.Empty;
tl.AppendLine($"Was '{origModifyDateStr}', now '{newModifyDateStr}'");
tl.PerformLayout(true);
page.Graphics.DrawTextLayout(tl, PointF.Empty);
doc.Save(stream);
}
File.Delete(fn);
// 完毕:
return 1;
}
}
}