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PrivateFrame.cs

//
// PrivateFrame.cs:
//
// Author:
//   Brian Nickel (brian.nickel@gmail.com)
//
// Copyright (C) 2005-2007 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.Collections;
using System;

namespace TagLib.Id3v2 {      
      /// <summary>
      ///    This class extends <see cref="Frame" />, implementing support for
      ///    ID3v2 Private (PRIV) Frames.
      /// </summary>
      /// <remarks>
      ///    <para>A <see cref="PrivateFrame" /> should be used for storing
      ///    values specific to the application that cannot or should not be
      ///    stored in another frame type.</para>
      /// </remarks>
      /// <example>
      ///    <para>Serializing a database entry and storing it in a private
      ///    field.</para>
      ///    <code lang="C#">
      /// using System;
      /// using System.IO;
      /// using System.Runtime.Serialization;
      /// using System.Text;
      /// using System.Xml.Serialization;
      /// using TagLib.Id3v2;
      ///
      /// public static class DbUtil
      /// {
      ///   public static void StoreDatabaseEntry (Tag tag, ISerializable dbEntry)
      ///   {
      ///         StringWriter data = new StringWriter (new StringBuilder ());
      ///         XmlSerializer serializer = new XmlSerializer (dbEntry.GetType ());
      ///         serializer.Serialize (data, dbEntry);
      ///         PrivateFrame frame = PrivateFrame.Get (tag, "org.MyProgram.DatabaseEntry", true);
      ///         frame.PrivateData = Encoding.UTF8.GetBytes (data.ToString ());
      ///   }
      ///   
      ///   public static object GetDatabaseEntry (Tag tag, Type type)
      ///   {
      ///         PrivateFrame frame = PrivateFrame.Get (tag, "org.MyProgram.DatabaseEntry", false);
      ///         if (frame == null)
      ///               return null;
      ///   
      ///         XmlSerializer serializer = new XmlSerializer (type);
      ///         return serializer.Deserialize (new MemoryStream (frame.PrivateData));
      ///   }
      /// }
      ///    </code>
      ///    <code lang="C++">
      /// #using &lt;System.dll>
      /// #using &lt;System.Xml.dll>
      /// #using &lt;taglib-sharp.dll>
      /// 
      /// using System;
      /// using System::IO;
      /// using System::Runtime::Serialization;
      /// using System::Text;
      /// using System::Xml::Serialization;
      /// using TagLib::Id3v2;
      /// 
      /// public ref class DbUtil abstract sealed
      /// {
      /// public:
      ///   static void StoreDatabaseEntry (Tag^ tag, ISerializable^ dbEntry)
      ///   {
      ///         StringWriter^ data = gcnew StringWriter (gcnew StringBuilder);
      ///         XmlSerializer serializer = gcnew XmlSerializer (dbEntry->GetType ());
      ///         serializer->Serialize (data, dbEntry);
      ///         PrivateFrame frame = PrivateFrame::Get (tag, L"org.MyProgram.DatabaseEntry", true);
      ///         frame.PrivateData = Encoding::UTF8->GetBytes (data->ToString ());
      ///   }
      ///   
      ///   static Object^ GetDatabaseEntry (Tag^ tag, Type^ type)
      ///   {
      ///         PrivateFrame^ frame = PrivateFrame::Get (tag, L"org.MyProgram.DatabaseEntry", false);
      ///         if (frame == null)
      ///               return null;
      ///   
      ///         XmlSerializer serializer = gcnew XmlSerializer (type);
      ///         return serializer->Deserialize (gcnew MemoryStream (frame->PrivateData));
      ///   }
      /// }
      ///    </code>
      ///    <code lang="VB">
      /// Imports System
      /// Imports System.IO
      /// Imports System.Runtime.Serialization
      /// Imports System.Text
      /// Imports System.Xml.Serialization
      /// Imports TagLib.Id3v2
      ///
      /// Public Shared Class DbUtil
      ///   Public Shared Sub StoreDatabaseEntry (tag As Tag, dbEntry As ISerializable)
      ///         Dim data As New StringWriter (New StringBuilder ())
      ///         Dim serializer As New XmlSerializer (dbEntry.GetType ())
      ///         serializer.Serialize (data, dbEntry)
      ///         Dim frame As PrivateFrame = PrivateFrame.Get (tag, "org.MyProgram.DatabaseEntry", True)
      ///         frame.PrivateData = Encoding.UTF8.GetBytes (data.ToString ())
      ///   End Sub
      ///   
      ///   Public Shared Sub GetDatabaseEntry (tag As Tag, type As Type)
      ///         Dim frame As PrivateFrame = PrivateFrame.Get (tag, "org.MyProgram.DatabaseEntry", False)
      ///         If frame Is Nothing Then Return Nothing
      ///   
      ///         Dim serializer As XmlSerializer = New XmlSerializer (type)
      ///         Return serializer.Deserialize (New MemoryStream (frame.PrivateData))
      ///   End Sub
      /// End Class
      ///    </code>
      ///    <code lang="Boo">
      /// import System
      /// import System.IO
      /// import System.Runtime.Serialization
      /// import System.Text
      /// import System.Xml.Serialization
      /// import TagLib.Id3v2
      /// 
      /// public static class DbUtil:
      ///   static def StoreDatabaseEntry (tag as Tag, dbEntry as ISerializable):
      ///         data as StringWriter = StringWriter (StringBuilder ())
      ///         serializer as XmlSerializer = XmlSerializer (dbEntry.GetType ())
      ///         serializer.Serialize (data, dbEntry)
      ///         frame as PrivateFrame = PrivateFrame.Get (tag, "org.MyProgram.DatabaseEntry", true)
      ///         frame.PrivateData = Encoding.UTF8.GetBytes (data.ToString ())
      ///   
      ///   static def GetDatabaseEntry (tag As Tag, type As Type):
      ///         frame as PrivateFrame = PrivateFrame.Get (tag, "org.MyProgram.DatabaseEntry", false)
      ///         if frame == null:
      ///               return null
      ///         
      ///         serializer as XmlSerializer = XmlSerializer (type)
      ///         return serializer.Deserialize (MemoryStream (frame.PrivateData))
      ///    </code>
      /// </example>
00156       public class PrivateFrame : Frame
      {
            #region Private Properties
            
            /// <summary>
            ///    Contains the owner of the current instance.
            /// </summary>
00163             private string owner = null;
            
            /// <summary>
            ///    Contains private data stored in the current instance.
            /// </summary>
00168             private ByteVector data  = null;
            
            #endregion
            
            
            
            #region Constructors
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PrivateFrame" /> for a specified owner and data.
            /// </summary>
            /// <param name="owner">
            ///    A <see cref="string" /> containing the owner of the new
            ///    frame.
            /// </param>
            /// <param name="data">
            ///    A <see cref="ByteVector" /> object containing the data
            ///    for the new frame.
            /// </param>
            /// <remarks>
            ///    When a frame is created, it is not automatically added to
            ///    the tag. Consider using <see cref="Get" /> for more
            ///    integrated frame creation.
            /// </remarks>
00193             public PrivateFrame (string owner, ByteVector data)
                  : base (FrameType.PRIV, 4)
            {
                  this.owner = owner;
                  this.data  = data;
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PrivateFrame" /> without data for a specified
            ///    owner.
            /// </summary>
            /// <param name="owner">
            ///    A <see cref="string" /> containing the owner of the new
            ///    frame.
            /// </param>
            /// <remarks>
            ///    When a frame is created, it is not automatically added to
            ///    the tag. Consider using <see cref="Get" /> for more
            ///    integrated frame creation.
            /// </remarks>
00214             public PrivateFrame (string owner) : this (owner, null)
            {
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PrivateFrame" /> 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>
00231             public PrivateFrame (ByteVector data, byte version)
                  : base (data, version)
            {
                  SetData (data, 0, version, true);
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PrivateFrame" /> 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>
00258             protected internal PrivateFrame (ByteVector data, int offset,
                                             FrameHeader header,
                                             byte version) : base(header)
            {
                  SetData (data, offset, version, false);
            }
            
            #endregion
            
            
            
            #region Public Properties
            
            /// <summary>
            ///    Gets the owner of the current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="string" /> containing the owner of the
            ///    current instance.
            /// </value>
            /// <remarks>
            ///    There should only be one frame with a given owner per
            ///    tag.
            /// </remarks>
00282             public string Owner {
                  get {return owner;}
            }
            
            /// <summary>
            ///    Gets and sets the private data stored in the current
            ///    instance.
            /// </summary>
            /// <value>
            ///    A <see cref="ByteVector" /> containing the private data
            ///    stored in the current instance.
            /// </value>
00294             public ByteVector PrivateData {
                  get {return data;}
                  set {data = value;}
            }
            
            #endregion
            
            
            
            #region Public Static Methods
            
            /// <summary>
            ///    Gets a specified private 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="owner">
            ///    A <see cref="string" /> specifying the owner 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="PrivateFrame" /> object containing the
            ///    matching frame, or <see langword="null" /> if a match
            ///    wasn't found and <paramref name="create" /> is <see
            ///    langword="false" />.
            /// </returns>
00325             public static PrivateFrame Get (Tag tag, string owner,
                                            bool create)
            {
                  PrivateFrame priv;
                  
                  foreach (Frame frame in tag.GetFrames (FrameType.PRIV)) {
                        priv = frame as PrivateFrame;
                        if (priv != null && priv.Owner == owner)
                              return priv;
                  }
                  
                  if (!create)
                        return null;
                  
                  priv = new PrivateFrame (owner);
                  tag.AddFrame (priv);
                  return priv;
            }
            
            #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>
00362             protected override void ParseFields (ByteVector data, byte version)
            {
                  if (data.Count < 1)
                        throw new CorruptFileException (
                              "A private frame must contain at least 1 byte.");
                  
                  ByteVectorCollection l = ByteVectorCollection.Split (
                        data,
                        ByteVector.TextDelimiter (StringType.Latin1),
                        1, 2);
                  
                  if (l.Count == 2) {
                        this.owner = l [0].ToString (StringType.Latin1);
                        this.data  = l [1];
                  }
            }
            
            /// <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>
00391             protected override ByteVector RenderFields (byte version)
            {
                  ByteVector v = new ByteVector ();
                  
                  if (version > 2) {
                        v.Add (ByteVector.FromString (owner, StringType.Latin1));
                        v.Add (ByteVector.TextDelimiter (StringType.Latin1));
                        v.Add (data);
                  }
                  
                  return v;
            }
            
            #endregion
      }
}

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