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GeneralEncapsulatedObjectFrame.cs

//
// GeneralEncapsulatedObjectFrame.cs:
//
// Author:
//   Brian Nickel (brian.nickel@gmail.com)
//
// Original Source:
//   generalencapsulatedobjectframe.cpp from TagLib
//
// Copyright (C) 2007 Brian Nickel
// Copyright (C) 2007 Scott Wheeler (Original Implementation)
// 
// 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.Collections;
using System;

namespace TagLib.Id3v2 {
      /// <summary>
      ///    This class extends <see cref="Frame" />, implementing support for
      ///    ID3v2 General Encapsulated Object (GEOB) Frames.
      /// </summary>
      /// <remarks>
      ///    <para>A <see cref="GeneralEncapsulatedObjectFrame" /> should be
      ///    used for storing files and other objects relevant to the file but
      ///    not supported by other frames.</para>
      /// </remarks>
00041       public class GeneralEncapsulatedObjectFrame : Frame
      {
#region Private Fields
            
            /// <summary>
            ///    Contains the text encoding to use when rendering the
            ///    current instance.
            /// </summary>
00049             private StringType encoding = Tag.DefaultEncoding;
            
            /// <summary>
            ///    Contains the mime type of <see cref="data" />.
            /// </summary>
00054             private string mime_type = null;
            
            /// <summary>
            ///    Contains the original file name.
            /// </summary>
00059             string file_name = null;
            
            /// <summary>
            ///    Contains the description.
            /// </summary>
00064             private string description = null;
            
            /// <summary>
            ///    Contains the data.
            /// </summary>
00069             private ByteVector data = null;
            
#endregion
            
            
            
#region Constructors
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="GeneralEncapsulatedObjectFrame" /> with no
            ///    contents.
            /// </summary>
00082             public GeneralEncapsulatedObjectFrame ()
                  : base (FrameType.GEOB, 4)
            {
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="GeneralEncapsulatedObjectFrame" /> by reading its
            ///    raw data in a specified ID3v2 version.
            /// </summary>
            /// <param name="data">
            ///    A <see cref="ByteVector" /> object starting with the raw
            ///    representation of the new frame.
            /// </param>
            /// <param name="version">
            ///    A <see cref="byte" /> indicating the ID3v2 version the
            ///    raw frame is encoded in.
            /// </param>
00100             public GeneralEncapsulatedObjectFrame (ByteVector data,
                                                   byte version)
                  : base (data, version)
            {
                  SetData (data, 0, version, true);
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="GeneralEncapsulatedObjectFrame" /> by reading its
            ///    raw data in a specified ID3v2 version.
            /// </summary>
            /// <param name="data">
            ///    A <see cref="ByteVector" /> object containing the raw
            ///    representation of the new frame.
            /// </param>
            /// <param name="offset">
            ///    A <see cref="int" /> indicating at what offset in
            ///    <paramref name="data" /> the frame actually begins.
            /// </param>
            /// <param name="header">
            ///    A <see cref="FrameHeader" /> containing the header of the
            ///    frame found at <paramref name="offset" /> in the data.
            /// </param>
            /// <param name="version">
            ///    A <see cref="byte" /> indicating the ID3v2 version the
            ///    raw frame is encoded in.
            /// </param>
00128             protected internal GeneralEncapsulatedObjectFrame (ByteVector data,
                                                               int offset,
                                                               FrameHeader header,
                                                               byte version)
                  : base(header)
            {
                  SetData (data, offset, version, false);
            }
            
#endregion
            
            
            
#region Public Properties
            
            /// <summary>
            ///    Gets and sets the text encoding to use when storing the
            ///    current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="string" /> containing the text encoding to
            ///    use when storing the current instance.
            /// </value>
            /// <remarks>
            ///    This encoding is overridden when rendering if <see
            ///    cref="Tag.ForceDefaultEncoding" /> is <see
            ///    langword="true" /> or the render version does not support
            ///    it.
            /// </remarks>
00157             public StringType TextEncoding {
                  get {return encoding;}
                  set {encoding = value;}
            }
            
            /// <summary>
            ///    Gets and sets the mime-type of the object stored in the
            ///    current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="string" /> containing the mime-type of the
            ///    object stored in the current instance.
            /// </value>
00170             public string MimeType {
                  get {
                        if (mime_type != null)
                              return mime_type;
                        
                        return string.Empty;
                  }
                  set {mime_type = value;}
            }
            
            /// <summary>
            ///    Gets and sets the file name of the object stored in the
            ///    current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="string" /> containing the file name of the
            ///    object stored in the current instance.
            /// </value>
00188             public string FileName {
                  get {
                        if (file_name != null)
                              return file_name;
                        
                        return string.Empty;
                  }
                  set {file_name = value;}
            }
            
            /// <summary>
            ///    Gets and sets the description stored in the current
            ///    instance.
            /// </summary>
            /// <value>
            ///    A <see cref="string" /> containing the description
            ///    stored in the current instance.
            /// </value>
            /// <remarks>
            ///    There should only be one frame with a matching
            ///    description and type per tag.
            /// </remarks>
00210             public string Description {
                  get {
                        if (description != null)
                              return description;
                        
                        return string.Empty;
                  }
                  set {description = value;}
            }
            
            /// <summary>
            ///    Gets and sets the object data stored in the current
            ///    instance.
            /// </summary>
            /// <value>
            ///    A <see cref="ByteVector" /> containing the object data
            ///    stored in the current instance.
            /// </value>
00228             public ByteVector Object {
                  get {return data != null ? data : new ByteVector ();}
                  set {data = value;}
            }
            
#endregion
            
            
            
#region Public Methods
            
            /// <summary>
            ///    Creates a text description of the current instance.
            /// </summary>
            /// <returns>
            ///    A <see cref="string" /> object containing a description
            ///    of the current instance.
            /// </returns>
00246             public override string ToString ()
            {
                  System.Text.StringBuilder builder
                        = new System.Text.StringBuilder ();
                  
                  if (Description.Length == 0) {
                        builder.Append (Description);
                        builder.Append (" ");
                  }
                  
                  builder.AppendFormat (
                        System.Globalization.CultureInfo.InvariantCulture,
                        "[{0}] {1} bytes", MimeType, Object.Count);
                  
                  return builder.ToString ();
            }
            
#endregion
            
            
            
#region Public Static Methods
            
            /// <summary>
            ///    Gets a specified encapsulated object frame from the
            ///    specified tag, optionally creating it if it does not
            ///    exist.
            /// </summary>
            /// <param name="tag">
            ///    A <see cref="Tag" /> object to search in.
            /// </param>
            /// <param name="description">
            ///    A <see cref="string" /> specifying the description to
            ///    match.
            /// </param>
            /// <param name="create">
            ///    A <see cref="bool" /> specifying whether or not to create
            ///    and add a new frame to the tag if a match is not found.
            /// </param>
            /// <returns>
            ///    A <see cref="GeneralEncapsulatedObjectFrame" /> object
            ///    containing the matching frame, or <see langword="null" />
            ///    if a match wasn't found and <paramref name="create" /> is
            ///    <see langword="false" />.
            /// </returns>
00291             public static GeneralEncapsulatedObjectFrame Get (Tag tag,
                                                              string description,
                                                              bool create)
            {
                  GeneralEncapsulatedObjectFrame geob;
                  foreach (Frame frame in tag.GetFrames (FrameType.GEOB)) {
                        geob = frame as GeneralEncapsulatedObjectFrame;
                        
                        if (geob == null)
                              continue;
                        
                        if (geob.Description != description)
                              continue;
                        
                        return geob;
                  }
                  
                  if (!create)
                        return null;
                  
                  geob = new GeneralEncapsulatedObjectFrame ();
                  geob.Description = description;
                  tag.AddFrame (geob);
                  return geob;
            }
            
#endregion
            
            
            
#region Protected Methods
            
            /// <summary>
            ///    Populates the values in the current instance by parsing
            ///    its field data in a specified version.
            /// </summary>
            /// <param name="data">
            ///    A <see cref="ByteVector" /> object containing the
            ///    extracted field data.
            /// </param>
            /// <param name="version">
            ///    A <see cref="byte" /> indicating the ID3v2 version the
            ///    field data is encoded in.
            /// </param>
            /// <exception cref="CorruptFileException">
            ///    <paramref name="data" /> contains less than 5 bytes.
            /// </exception>
00338             protected override void ParseFields (ByteVector data,
                                                 byte version)
            {
                  if (data.Count < 4)
                        throw new CorruptFileException (
                              "An object frame must contain at least 4 bytes.");
                  
                  int start = 0;
                  
                  encoding =  (StringType) data [start++];
                  
                  int end = data.Find (
                        ByteVector.TextDelimiter (StringType.Latin1),
                        start);
                  
                  if (end < start)
                        return;
                  
                  mime_type = data.ToString (StringType.Latin1, start,
                        end - start);
                  
                  ByteVector delim = ByteVector.TextDelimiter (
                        encoding);
                  start = end + 1;
                  end = data.Find (delim, start, delim.Count);
                  
                  if (end < start)
                        return;
                  
                  file_name = data.ToString (encoding, start,
                        end - start);
                  start = end + delim.Count;
                  end = data.Find (delim, start, delim.Count);
                  
                  if (end < start)
                        return;
                  
                  description = data.ToString (encoding, start,
                        end - start);
                  start = end + delim.Count;
                  
                  data.RemoveRange (0, start);
                  this.data = data;
            }
            
            /// <summary>
            ///    Renders the values in the current instance into field
            ///    data for a specified version.
            /// </summary>
            /// <param name="version">
            ///    A <see cref="byte" /> indicating the ID3v2 version the
            ///    field data is to be encoded in.
            /// </param>
            /// <returns>
            ///    A <see cref="ByteVector" /> object containing the
            ///    rendered field data.
            /// </returns>
00395             protected override ByteVector RenderFields (byte version)
            {
                  StringType encoding = CorrectEncoding (this.encoding,
                        version);
                  ByteVector v = new ByteVector ();
                  
                  v.Add ((byte) encoding);
                  
                  if (MimeType != null)
                        v.Add (ByteVector.FromString (MimeType,
                              StringType.Latin1));
                  v.Add (ByteVector.TextDelimiter (StringType.Latin1));
                  
                  if (FileName != null)
                        v.Add (ByteVector.FromString (FileName,
                              encoding));
                  v.Add (ByteVector.TextDelimiter (encoding));
                  
                  if (Description != null)
                        v.Add (ByteVector.FromString (Description,
                              encoding));
                  v.Add (ByteVector.TextDelimiter (encoding));
                  
                  v.Add (data);
                  return v;
            }
            
#endregion
            
            
            
#region ICloneable
            
            /// <summary>
            ///    Creates a deep copy of the current instance.
            /// </summary>
            /// <returns>
            ///    A new <see cref="Frame" /> object identical to the
            ///    current instance.
            /// </returns>
00435             public override Frame Clone ()
            {
                  GeneralEncapsulatedObjectFrame frame =
                        new GeneralEncapsulatedObjectFrame ();
                  frame.encoding = encoding;
                  frame.mime_type = mime_type;
                  frame.file_name = file_name;
                  frame.description = description;
                  if (data != null)
                        frame.data = new ByteVector (data);
                  return frame;
            }
            
#endregion
      }
}

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