/PDFsharp/code/PdfSharp/PdfSharp.Pdf.Advanced/PdfTrailer.cs

#region PDFsharp - A .NET library for processing PDF

//

// Authors:

//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)

//

// Copyright (c) 2005-2009 empira Software GmbH, Cologne (Germany)

//

// http://www.pdfsharp.com

// http://sourceforge.net/projects/pdfsharp

//

// Permission is hereby granted, free of charge, to any person obtaining a

// copy of this software and associated documentation files (the "Software"),

// to deal in the Software without restriction, including without limitation

// the rights to use, copy, modify, merge, publish, distribute, sublicense,

// and/or sell copies of the Software, and to permit persons to whom the

// Software is furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included

// in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 

// DEALINGS IN THE SOFTWARE.

#endregion



using System;

using System.Diagnostics;

using System.Collections;

using PdfSharp.Pdf.IO;

using PdfSharp.Pdf.Security;

using PdfSharp.Pdf.Internal;



namespace PdfSharp.Pdf.Advanced

{

  /// <summary>

  /// Represents a PDF trailer dictionary. Even trailers are dictionaries their never have a cross

  /// reference entry in PdfReferenceTable.

  /// </summary>

  internal sealed class PdfTrailer : PdfDictionary

  {

    /// <summary>

    /// Initializes a new instance of PdfTrailer.

    /// </summary>

    public PdfTrailer(PdfDocument document) : base(document)

    {

      this.document = document;

    }



    public int Size

    {

      get {return Elements.GetInteger(Keys.Size);}

      set {Elements.SetInteger(Keys.Size, value);}

    }



    // TODO: needed when linearized...

    //public int Prev

    //{

    //  get {return Elements.GetInteger(Keys.Prev);}

    //}



    public PdfDocumentInformation Info

    {

      get {return (PdfDocumentInformation)Elements.GetValue(Keys.Info, VCF.CreateIndirect);}

    }



    /// <summary>

    /// (Required; must be an indirect reference)

    /// The catalog dictionary for the PDF document contained in the file.

    /// </summary>

    public PdfCatalog Root

    {

      get {return (PdfCatalog)Elements.GetValue(PdfTrailer.Keys.Root, VCF.CreateIndirect);}

    }



    /// <summary>

    /// Gets the first or second document identifier.

    /// </summary>

    public string GetDocumentID(int index)

    {

      if (index < 0 || index > 1)

        throw new ArgumentOutOfRangeException("index", index, "Index must be 0 or 1.");



      PdfArray array = Elements[Keys.ID] as PdfArray;

      if (array == null || array.Elements.Count < 2)

        return "";

      PdfItem item = array.Elements[index];

      if (item is PdfString)

        return ((PdfString)item).Value;

      return "";

    }



    /// <summary>

    /// Sets the first or second document identifier.

    /// </summary>

    public void SetDocumentID(int index, string value)

    {

      if (index < 0 || index > 1)

        throw new ArgumentOutOfRangeException("index", index, "Index must be 0 or 1.");



      PdfArray array = Elements[Keys.ID] as PdfArray;

      if (array == null || array.Elements.Count < 2)

        array = CreateNewDocumentIDs();

      array.Elements[index] = new PdfString(value, PdfStringFlags.HexLiteral);

    }



    /// <summary>

    /// Creates and sets two identical new document IDs.

    /// </summary>

    internal PdfArray CreateNewDocumentIDs()

    {

      PdfArray array = new PdfArray(this.document);

      byte[] docID = Guid.NewGuid().ToByteArray();

      string id = PdfEncoders.RawEncoding.GetString(docID, 0, docID.Length);

      array.Elements.Add(new PdfString(id, PdfStringFlags.HexLiteral));

      array.Elements.Add(new PdfString(id, PdfStringFlags.HexLiteral));

      Elements[Keys.ID] = array;

      return array;

    }



    /// <summary>

    /// Gets the standard security handler.

    /// </summary>

    public PdfStandardSecurityHandler SecurityHandler

    {

      get 

      {

        if (this.securityHandler == null)

          this.securityHandler = (PdfStandardSecurityHandler)Elements.GetValue(Keys.Encrypt, VCF.CreateIndirect);

        return this.securityHandler;

      }

    }

    internal PdfStandardSecurityHandler securityHandler;



    //internal override void WriteDictionaryElement(PdfSharp.Pdf.IO.PdfWriter writer, PdfName key)

    //{

    //  //if (key == Keys.ID)

    //  //{

    //  //  PdfArray array = Elements[key] as PdfArray;

    //  //  PdfItem item = array.Elements[0];

    //  //  //base.WriteDictionaryElement(writer, key);

    //  //  return;

    //  //}

    //  base.WriteDictionaryElement (writer, key);

    //}



    internal override void WriteObject(PdfWriter writer)

    {

      // Delete /XRefStm entry, if any

      this.elements.Remove(Keys.XRefStm);



      // Don't encypt myself

      PdfStandardSecurityHandler securityHandler = writer.SecurityHandler;

      writer.SecurityHandler = null;

      base.WriteObject(writer);

      writer.SecurityHandler = securityHandler;

    }



    /// <summary>

    /// Replace temporary irefs by their correct counterparts from the iref table.

    /// </summary>

    internal void Finish()

    {

      // \Root

      PdfReference iref = document.trailer.Elements[PdfTrailer.Keys.Root] as PdfReference;

      if (iref != null && iref.Value == null)

      {

        iref = document.irefTable[iref.ObjectID];

        Debug.Assert(iref.Value != null);

        this.document.trailer.Elements[PdfTrailer.Keys.Root] = iref;

      }



      // \Info

      iref = this.document.trailer.Elements[PdfTrailer.Keys.Info] as PdfReference;

      if (iref != null && iref.Value == null)

      {

        iref = document.irefTable[iref.ObjectID];

        Debug.Assert(iref.Value != null);

        this.document.trailer.Elements[PdfTrailer.Keys.Info] = iref;

      }



      // \Encrypt

      iref = this.document.trailer.Elements[PdfTrailer.Keys.Encrypt] as PdfReference;

      if (iref != null)

      {

        iref = document.irefTable[iref.ObjectID];

        Debug.Assert(iref.Value != null);

        this.document.trailer.Elements[PdfTrailer.Keys.Encrypt] = iref;



        // The encryption dictionary (security handler) was read in before the XRefTable construction 

        // was completed. The next lines fix that state (it take several hours to find that bugs...).

        iref.Value = this.document.trailer.securityHandler;

        this.document.trailer.securityHandler.Reference = iref;

        iref.Value.Reference = iref;

      }



      Elements.Remove(Keys.Prev);



      this.document.irefTable.IsUnderConstruction = false;

    }



    /// <summary>

    /// Predefined keys of this dictionary.

    /// </summary>

    internal sealed class Keys : KeysBase

    {

      /// <summary>

      /// (Required; must not be an indirect reference) The total number of entries in the file’s 

      /// cross-reference table, as defined by the combination of the original section and all

      /// update sections. Equivalently, this value is 1 greater than the highest object number

      /// used in the file.

      /// Note: Any object in a cross-reference section whose number is greater than this value is

      /// ignored and considered missing.

      /// </summary>

      [KeyInfo(KeyType.Integer | KeyType.Required)]

      public const string Size = "/Size";



      /// <summary>

      /// (Present only if the file has more than one cross-reference section; must not be an indirect

      /// reference) The byte offset from the beginning of the file to the beginning of the previous 

      /// cross-reference section.

      /// </summary>

      [KeyInfo(KeyType.Integer | KeyType.Optional)]

      public const string Prev = "/Prev";



      /// <summary>

      /// (Required; must be an indirect reference) The catalog dictionary for the PDF document

      /// contained in the file.

      /// </summary>

      [KeyInfo(KeyType.Dictionary | KeyType.Required, typeof(PdfCatalog))]

      public const string Root = "/Root";



      /// <summary>

      /// (Required if document is encrypted; PDF 1.1) The document’s encryption dictionary.

      /// </summary>

      [KeyInfo(KeyType.Dictionary | KeyType.Optional, typeof(PdfStandardSecurityHandler))]

      public const string Encrypt = "/Encrypt";



      /// <summary>

      /// (Optional; must be an indirect reference) The document’s information dictionary.

      /// </summary>

      [KeyInfo(KeyType.Dictionary | KeyType.Optional, typeof(PdfDocumentInformation))]

      public const string Info = "/Info";



      /// <summary>

      /// (Optional, but strongly recommended; PDF 1.1) An array of two strings constituting

      /// a file identifier for the file. Although this entry is optional, 

      /// its absence might prevent the file from functioning in some workflows

      /// that depend on files being uniquely identified.

      /// </summary>

      [KeyInfo(KeyType.Array | KeyType.Optional)]

      public const string ID = "/ID";



      /// <summary>

      /// (Optional) The byte offset from the beginning of the file of a cross-reference stream.

      /// </summary>

      [KeyInfo(KeyType.Integer | KeyType.Optional)]

      public const string XRefStm = "/XRefStm";



      /// <summary>

      /// Gets the KeysMeta for these keys.

      /// </summary>

      public static DictionaryMeta Meta

      {

        get

        {

          if (Keys.meta == null)

            Keys.meta = CreateMeta(typeof(Keys));

          return Keys.meta;

        }

      }

      static DictionaryMeta meta;

    }



    /// <summary>

    /// Gets the KeysMeta of this dictionary type.

    /// </summary>

    internal override DictionaryMeta Meta

    {

      get {return Keys.Meta;}

    }

  }

}