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PdfMerger: basic functionality implemented

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I has a lot of unknown and TODO please look at them
This commit is contained in:
Inusual
2020-02-24 00:42:12 -04:00
committed by Eliot Jones
parent 013cbd14e0
commit f485826751
3 changed files with 471 additions and 0 deletions
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26
src/UglyToad.PdfPig.Tests/Writer/PdfMergerTests.cs Normal file
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namespace UglyToad.PdfPig.Tests.Writer
{
using Integration;
using PdfPig.Writer;
using Xunit;
public class PdfMergerTests
{
[Fact]
public void CanMerge2SimpleDocuments()
{
var one = IntegrationHelpers.GetDocumentPath("Single Page Simple - from inkscape.pdf");
var two = IntegrationHelpers.GetDocumentPath("Single Page Simple - from open office.pdf");
var result = PdfMerger.Merge(one, two);
// FIX: Enable UseLenianParseOff
using (var document = PdfDocument.Open(result/*, ParsingOptions.LenientParsingOff */))
{
Assert.Equal(2, document.NumberOfPages);
Assert.Equal(1.7m, document.Version);
}
}
}
}

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src/UglyToad.PdfPig/Writer/Merging/ObjectsTree.cs Normal file
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namespace UglyToad.PdfPig.Writer.Merging
{
using Content;
using CrossReference;
using Tokens;
// I don't see the purpose of this class, @Elliot maybe you can explain to me the purpose
internal class ObjectsTree
{
public TrailerDictionary TrailerDictionary { get; }
public ObjectToken TrailerObject { get; }
public Catalog Catalog { get; }
public ObjectsTree(TrailerDictionary trailerDictionary, ObjectToken trailerObject,
Catalog catalog)
{
TrailerDictionary = trailerDictionary;
TrailerObject = trailerObject;
Catalog = catalog;
}
}
}

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src/UglyToad.PdfPig/Writer/PdfMerger.cs Normal file
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namespace UglyToad.PdfPig.Writer
{
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using Content;
using Core;
using CrossReference;
using Encryption;
using Filters;
using Logging;
using Merging;
using Parser;
using Parser.FileStructure;
using Parser.Parts;
using Tokenization.Scanner;
using Tokens;
using UglyToad.PdfPig.Exceptions;
using UglyToad.PdfPig.Graphics.Operations;
using UglyToad.PdfPig.Writer.Fonts;
/// <summary>
/// Merges PDF documents into each other.
/// </summary>
public static class PdfMerger
{
private static readonly ILog Log = new NoOpLog();
private static readonly IFilterProvider FilterProvider = new MemoryFilterProvider(new DecodeParameterResolver(Log),
new PngPredictor(), Log);
/// <summary>
/// Merge two PDF documents together with the pages from <see cref="file1"/>
/// followed by <see cref="file2"/>.
/// </summary>
public static byte[] Merge(string file1, string file2)
{
if (file1 == null)
{
throw new ArgumentNullException(nameof(file1));
}
if (file2 == null)
{
throw new ArgumentNullException(nameof(file2));
}
return Merge(new[]
{
File.ReadAllBytes(file1),
File.ReadAllBytes(file2)
});
}
/// <summary>
/// Merge the set of PDF documents.
/// </summary>
public static byte[] Merge(IReadOnlyList<byte[]> files)
{
if (files == null)
{
throw new ArgumentNullException(nameof(files));
}
const bool isLenientParsing = true;
using var documentBuilder = new DocumentBuilder();
foreach (var file in files)
{
var inputBytes = new ByteArrayInputBytes(file);
var coreScanner = new CoreTokenScanner(inputBytes);
var version = FileHeaderParser.Parse(coreScanner, true, Log);
var bruteForceSearcher = new BruteForceSearcher(inputBytes);
var xrefValidator = new XrefOffsetValidator(Log);
var objectChecker = new XrefCosOffsetChecker(Log, bruteForceSearcher);
var crossReferenceParser = new CrossReferenceParser(Log, xrefValidator, objectChecker, new Parser.Parts.CrossReference.CrossReferenceStreamParser(FilterProvider));
var crossReferenceOffset = FileTrailerParser.GetFirstCrossReferenceOffset(inputBytes, coreScanner, isLenientParsing);
var objectLocations = bruteForceSearcher.GetObjectLocations();
CrossReferenceTable crossReference = null;
var locationProvider = new ObjectLocationProvider(() => crossReference, bruteForceSearcher);
// I'm not using the BruteForceObjectLocationProvider because, the offset that it give are wrong by +2
// var locationProvider = new BruteForcedObjectLocationProvider(objectLocations);
var pdfScanner = new PdfTokenScanner(inputBytes, locationProvider, FilterProvider, NoOpEncryptionHandler.Instance);
crossReference = crossReferenceParser.Parse(inputBytes, isLenientParsing, crossReferenceOffset, version.OffsetInFile, pdfScanner, coreScanner);
var trailerDictionary = crossReference.Trailer;
var (trailerRef, catalogDictionaryToken) = ParseCatalog(crossReference, pdfScanner, out var encryptionDictionary);
if (encryptionDictionary != null)
{
// TODO: Find option of how to pass password for the documents...
throw new PdfDocumentEncryptedException("Unable to merge document with password");
// pdfScanner.UpdateEncryptionHandler(new EncryptionHandler(encryptionDictionary, trailerDictionary, new[] { string.Empty }));
}
var objectsTree = new ObjectsTree(trailerDictionary, pdfScanner.Get(trailerRef),
CatalogFactory.Create(crossReference.Trailer.Root, catalogDictionaryToken, pdfScanner, isLenientParsing));
var objectsLocation = bruteForceSearcher.GetObjectLocations();
var root = pdfScanner.Get(trailerDictionary.Root);
var tokens = new List<IToken>();
pdfScanner.Seek(0);
while (pdfScanner.MoveNext())
{
tokens.Add(pdfScanner.CurrentToken);
}
if (!(tokens.Count == objectLocations.Count))
{
// Do we really need to check this?
throw new PdfDocumentFormatException("Something whent wrong while reading file");
}
documentBuilder.AppendNewDocument(objectsTree, pdfScanner);
}
return documentBuilder.Build();
}
// This method is a basically a copy of the method UglyToad.PdfPig.Parser.PdfDocumentFactory.ParseTrailer()
private static (IndirectReference, DictionaryToken) ParseCatalog(CrossReferenceTable crossReferenceTable,
IPdfTokenScanner pdfTokenScanner,
out EncryptionDictionary encryptionDictionary)
{
encryptionDictionary = null;
if (crossReferenceTable.Trailer.EncryptionToken != null)
{
if (!DirectObjectFinder.TryGet(crossReferenceTable.Trailer.EncryptionToken, pdfTokenScanner,
out DictionaryToken encryptionDictionaryToken))
{
throw new PdfDocumentFormatException($"Unrecognized encryption token in trailer: {crossReferenceTable.Trailer.EncryptionToken}.");
}
encryptionDictionary = EncryptionDictionaryFactory.Read(encryptionDictionaryToken, pdfTokenScanner);
}
var rootDictionary = DirectObjectFinder.Get<DictionaryToken>(crossReferenceTable.Trailer.Root, pdfTokenScanner);
if (!rootDictionary.ContainsKey(NameToken.Type))
{
rootDictionary = rootDictionary.With(NameToken.Type, NameToken.Catalog);
}
return (crossReferenceTable.Trailer.Root, rootDictionary);
}
// Note: I don't think making this a disposable is a good idea.
// Also, suggestion for name?
private class DocumentBuilder : IDisposable
{
private bool isDisposed = false;
private MemoryStream Memory = new MemoryStream();
private readonly BuilderContext Context = new BuilderContext();
private readonly List<IndirectReferenceToken> DocumentPages = new List<IndirectReferenceToken>();
private IndirectReferenceToken RootPagesIndirectReference;
public DocumentBuilder()
{
var reserved = Context.ReserveNumber();
RootPagesIndirectReference = new IndirectReferenceToken(new IndirectReference(reserved, 0));
WriteHeaderToStream();
}
private void WriteHeaderToStream()
{
// Copied from UglyToad.PdfPig.Writer.PdfDocumentBuilder
WriteString("%PDF-1.7", Memory);
// Files with binary data should contain a 2nd comment line followed by 4 bytes with values > 127
Memory.WriteText("%");
Memory.WriteByte(169);
Memory.WriteByte(205);
Memory.WriteByte(196);
Memory.WriteByte(210);
Memory.WriteNewLine();
}
public void AppendNewDocument(ObjectsTree newDocument, IPdfTokenScanner tokenScanner)
{
if (isDisposed)
{
throw new ObjectDisposedException("Merger disposed already");
}
/*
* I decided that I want to have an /Pages object for each document's pages. That way I avoided resource name conflict
* But I guess that doesn't matter either way? So that part can be eliminated?
*/
var pageReferences = ConstructPageReferences(newDocument.Catalog.PageTree, tokenScanner);
var pagesDictionary = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.Type, NameToken.Pages },
{ NameToken.Kids, new ArrayToken(pageReferences) },
{ NameToken.Count, new NumericToken(pageReferences.Count) },
{ NameToken.Parent, RootPagesIndirectReference }
});
var pagesRef = Context.WriteObject(Memory, pagesDictionary);
DocumentPages.Add(new IndirectReferenceToken(pagesRef.Number));
}
private IReadOnlyList<IndirectReferenceToken> ConstructPageReferences(PageTreeNode treeNode, IPdfTokenScanner tokenScanner)
{
var reserved = Context.ReserveNumber();
var parentIndirect = new IndirectReferenceToken(new IndirectReference(reserved, 0));
var pageReferences = new List<IndirectReferenceToken>();
foreach (var pageNode in treeNode.Children)
{
if (!pageNode.IsPage)
{
var nestedPageReferences = ConstructPageReferences(pageNode, tokenScanner);
var pagesDictionary = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.Type, NameToken.Pages },
{ NameToken.Kids, new ArrayToken(nestedPageReferences) },
{ NameToken.Count, new NumericToken(nestedPageReferences.Count) },
{ NameToken.Parent, parentIndirect }
});
var pagesRef = Context.WriteObject(Memory, pagesDictionary);
pageReferences.Add(new IndirectReferenceToken(pagesRef.Number));
continue;
}
var pageDictionary = new Dictionary<NameToken, IToken>
{
{NameToken.Parent, parentIndirect},
};
foreach(var setPair in pageNode.NodeDictionary.Data)
{
var name = setPair.Key;
var token = setPair.Value;
if (name == NameToken.Parent)
{
// Skip Parent token, since we have to reassign it
continue;
}
pageDictionary.Add(NameToken.Create(name), CopyToken(token, tokenScanner));
}
var pageRef = Context.WriteObject(Memory, new DictionaryToken(pageDictionary), reserved);
pageReferences.Add(new IndirectReferenceToken(pageRef.Number));
}
return pageReferences;
}
private IToken CopyToken(IToken tokenToCopy, IPdfTokenScanner tokenScanner)
{
if (tokenToCopy is DictionaryToken dictionaryToken)
{
var newContent = new Dictionary<NameToken, IToken>();
foreach (var setPair in dictionaryToken.Data)
{
var name = setPair.Key;
var token = setPair.Value;
newContent.Add(NameToken.Create(name), CopyToken(token, tokenScanner));
}
return new DictionaryToken(newContent);
}
else if (tokenToCopy is ArrayToken arrayToken)
{
var newArray = new List<IToken>(arrayToken.Length);
foreach (var token in arrayToken.Data)
{
newArray.Add(CopyToken(token, tokenScanner));
}
return new ArrayToken(newArray);
}
else if (tokenToCopy is IndirectReferenceToken referenceToken)
{
var tokenObject = DirectObjectFinder.Get<IToken>(referenceToken.Data, tokenScanner);
// Is this even a allowed?
Debug.Assert(!(tokenObject is IndirectReferenceToken));
var newToken = CopyToken(tokenObject, tokenScanner);
var objToken = Context.WriteObject(Memory, newToken);
return new IndirectReferenceToken(objToken.Number);
}
else
{
// TODO: Should we do a deep copy of the token?
return tokenToCopy;
}
}
public byte[] Build()
{
if (isDisposed)
{
throw new ObjectDisposedException("Merger disposed already");
}
if (DocumentPages.Count < 1)
{
throw new PdfDocumentFormatException("Empty document");
}
var pagesDictionary = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.Type, NameToken.Pages },
{ NameToken.Kids, new ArrayToken(DocumentPages) },
{ NameToken.Count, new NumericToken(DocumentPages.Count) }
});
var pagesRef = Context.WriteObject(Memory, pagesDictionary, (int)RootPagesIndirectReference.Data.ObjectNumber);
var catalog = new DictionaryToken(new Dictionary<NameToken, IToken>
{
{ NameToken.Type, NameToken.Catalog },
{ NameToken.Pages, new IndirectReferenceToken(pagesRef.Number) }
});
var catalogRef = Context.WriteObject(Memory, catalog);
TokenWriter.WriteCrossReferenceTable(Context.ObjectOffsets, catalogRef, Memory, null);
var bytes = Memory.ToArray();
Dispose();
return bytes;
}
// Note: This method is copied from UglyToad.PdfPig.Writer.PdfDocumentBuilder
private static void WriteString(string text, MemoryStream stream, bool appendBreak = true)
{
var bytes = OtherEncodings.StringAsLatin1Bytes(text);
stream.Write(bytes, 0, bytes.Length);
if (appendBreak)
{
stream.WriteNewLine();
}
}
public void Dispose()
{
if (isDisposed)
return;
Memory.Dispose();
Memory = null;
isDisposed = true;
}
}
// Currently unused becauase, brute force search give the wrong offset (+2)
private class BruteForcedObjectLocationProvider : IObjectLocationProvider
{
private readonly Dictionary<IndirectReference, long> objectLocations;
private readonly Dictionary<IndirectReference, ObjectToken> cache = new Dictionary<IndirectReference, ObjectToken>();
public BruteForcedObjectLocationProvider(IReadOnlyDictionary<IndirectReference, long> objectLocations)
{
this.objectLocations = objectLocations.ToDictionary(x => x.Key, x => x.Value);
}
public bool TryGetOffset(IndirectReference reference, out long offset)
{
var result = objectLocations.TryGetValue(reference, out offset);
//offset -= 2;
return result;
}
public void UpdateOffset(IndirectReference reference, long offset)
{
objectLocations[reference] = offset;
}
public bool TryGetCached(IndirectReference reference, out ObjectToken objectToken)
{
return cache.TryGetValue(reference, out objectToken);
}
public void Cache(ObjectToken objectToken, bool force = false)
{
if (!TryGetOffset(objectToken.Number, out var offsetExpected) || force)
{
cache[objectToken.Number] = objectToken;
}
if (offsetExpected != objectToken.Position)
{
return;
}
cache[objectToken.Number] = objectToken;
}
}
}
}