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IsoChunkOffsetBox.cs

//
// IsoChunkOffsetBox.cs: Provides an implementation of a ISO/IEC 14496-12
// ChunkOffsetBox.
//
// Author:
//   Brian Nickel (brian.nickel@gmail.com)
//
// Copyright (C) 2006-2007 Brian Nickel
// 
// This library is free software; you can redistribute it and/or modify
// it  under the terms of the GNU Lesser General Public License version
// 2.1 as published by the Free Software Foundation.
//
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
// USA
//

using System;

namespace TagLib.Mpeg4 {
      /// <summary>
      ///    This class extends <see cref="FullBox" /> to provide an
      ///    implementation of a ISO/IEC 14496-12 ChunkOffsetBox.
      /// </summary>
      /// <remarks>
      ///    <see cref="IsoChunkOffsetBox" /> and <see
      ///    cref="IsoChunkLargeOffsetBox" /> contain offsets of media data
      ///    within the file. As such, if the file changes by even one byte,
      ///    these values are devalidatated and the box will have to be
      ///    overwritten to maintain playability.
      /// </remarks>
00039       public class IsoChunkOffsetBox : FullBox
      {
            #region Private Fields
            
            /// <summary>
            ///    Contains the chunk offsets.
            /// </summary>
00046             private uint [] offsets;
            
            #endregion
            
            
            
            #region Constructors
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="IsoChunkOffsetBox" /> with a provided header and
            ///    handler by reading the contents from a specified file.
            /// </summary>
            /// <param name="header">
            ///    A <see cref="BoxHeader" /> object containing the header
            ///    to use for the new instance.
            /// </param>
            /// <param name="file">
            ///    A <see cref="TagLib.File" /> object to read the contents
            ///    of the box from.
            /// </param>
            /// <param name="handler">
            ///    A <see cref="IsoHandlerBox" /> object containing the
            ///    handler that applies to the new instance.
            /// </param>
00071             public IsoChunkOffsetBox (BoxHeader header, TagLib.File file,
                                      IsoHandlerBox handler)
                  : base (header, file, handler)
            {
                  ByteVector box_data = file.ReadBlock (DataSize);
                  
                  offsets = new uint [(int)
                        box_data.Mid (0, 4).ToUInt ()];
                  
                  for (int i = 0; i < offsets.Length; i ++)
                        offsets [i] = box_data.Mid (4 + i * 4,
                              4).ToUInt ();
            }
            
            #endregion
            
            
            
            #region Public Properties
            
            /// <summary>
            ///    Gets and sets the data contained in the current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="ByteVector" /> object containing the data
            ///    contained in the current instance.
            /// </value>
00098             public override ByteVector Data {
                  get {
                        ByteVector output = ByteVector.FromUInt ((uint)
                              offsets.Length);
                        for (int i = 0; i < offsets.Length; i ++)
                              output.Add (ByteVector.FromUInt (
                                    offsets [i]));
                        
                        return output;
                  }
            }
            
            /// <summary>
            ///    Gets the offset table contained in the current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="uint[]" /> containing the offset table
            ///    contained in the current instance.
            /// </value>
00117             public uint [] Offsets {
                  get {return offsets;}
            }
            
            #endregion
            
            
            
            #region Public Methods
            
            /// <summary>
            ///    Overwrites the existing box in the file after updating
            ///    the table for a size change.
            /// </summary>
            /// <param name="file">
            ///    A <see cref="File" /> object containing the file to which
            ///    the current instance belongs and wo which modifications
            ///    must be applied.
            /// </param>
            /// <param name="sizeDifference">
            ///    A <see cref="long" /> value containing the size
            ///    change that occurred in the file.
            /// </param>
            /// <param name="after">
            ///    A <see cref="long" /> value containing the position in
            ///    the file after which offsets will be invalidated. If an
            ///    offset is before this point, it won't be updated.
            /// </param>
            /// <exception cref="ArgumentNullException">
            ///    <param name="file" /> is <see langword="null" />.
            /// </exception>
00148             public void Overwrite (File file, long sizeDifference,
                                   long after)
            {
                  if (file == null)
                        throw new ArgumentNullException ("file");
                  
                  file.Insert (Render (sizeDifference, after),
                        Header.Position, Size);
            }
            
            /// <summary>
            ///    Renders the current instance after updating the table for
            ///    a size change.
            /// </summary>
            /// <param name="sizeDifference">
            ///    A <see cref="long" /> value containing the size
            ///    change that occurred in the file.
            /// </param>
            /// <param name="after">
            ///    A <see cref="long" /> value containing the position in
            ///    the file after which offsets will be invalidated. If an
            ///    offset is before this point, it won't be updated.
            /// </param>
            /// <returns>
            ///    A <see cref="ByteVector" /> object containing the
            ///    rendered version of the file.
            /// </returns>
00175             public ByteVector Render (long sizeDifference, long after)
            {
                  for (int i = 0; i < offsets.Length; i ++)
                        if (offsets [i] >= (uint) after)
                              offsets [i] = (uint)
                                    (offsets [i] + sizeDifference);
                  
                  return Render ();
            }
            
            #endregion
      }
}

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