// 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 try to read its metadata.
// Keep in mind that in some cases metadata in a PDF may also be encrypted, in which case
// reading it without the password is impossible.
// For reference, the loaded PDF is protected with the owner password 'owner' and user password 'user'.
public class NoPassGetMetadata
{
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);
// 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 };
// 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;
if (!metadataIsEncrypted)
{
Metadata m = docSrc.Metadata;
tl.AppendLine("The PDF has unencrypted metadata:", captionFmt);
tl.AppendLine($" Copyright: {m.Copyright}");
tl.AppendLine($" CreatorTool: {m.CreatorTool}");
if (m.CreateDate.HasValue)
tl.AppendLine($" CreateDate: {m.CreateDate.Value.ToUniversalTime():R}");
tl.AppendLine($" Description: {m.Description}");
if (m.ModifyDate.HasValue)
tl.AppendLine($" ModifyDate: {m.ModifyDate.Value.ToUniversalTime():R}");
tl.AppendLine($" Producer: {m.Producer}");
tl.AppendLine($" Title: {m.Title}");
}
else
{
tl.AppendLine("Cannot read metadata because the PDF metadata is encrypted.", captionFmt);
}
// Render the results:
tl.PerformLayout(true);
while (true)
{
var splitResult = tl.Split(null, out TextLayout rest);
page.Graphics.DrawTextLayout(tl, PointF.Empty);
if (splitResult != SplitResult.Split)
break;
tl = rest;
tl.MarginTop = tl.Resolution;
page = doc.Pages.Add();
}
// 完毕:
doc.Save(stream);
return doc.Pages.Count;
}
}
}