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PlayCountFrame.cs

//
// PlayCountFrame.cs:
//
// Author:
//   Brian Nickel (brian.nickel@gmail.com)
//
// Copyright (C) 2007 Brian Nickel
// 
// 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.
//

using System;

namespace TagLib.Id3v2 {
      /// <summary>
      ///    This class extends <see cref="Frame" />, implementing support for
      ///    ID3v2 Play Count (PCNT) Frames.
      /// </summary>
      /// <example>
      ///    <para>Getting and incrementing the play count of a file.</para>
      ///    <code lang="C#">
      /// using TagLib;
      /// using TagLib.Id3v2;
      ///
      /// public static class TrackUtil
      /// {
      ///   public static int GetPlayCount (string filename)
      ///   {
      ///         File file = File.Create (filename, ReadStyle.None);
      ///         Id3v2.Tag tag = file.GetTag (TagTypes.Id3v2, false) as Id3v2.Tag;
      ///         if (tag == null)
      ///               return 0;
      ///         
      ///         PlayCountFrame frame = PlayCountFrame.Get (tag, false);
      ///         if (frame == null)
      ///               return 0;
      ///
      ///         return frame.PlayCount;
      ///   }
      ///   
      ///   public static void IncrementPlayCount (string filename)
      ///   {
      ///         File file = File.Create (filename, ReadStyle.None);
      ///         Id3v2.Tag tag = file.GetTag (TagTypes.Id3v2, true) as Id3v2.Tag;
      ///         if (tag == null)
      ///               return;
      ///         
      ///         PlayCountFrame.Get (tag, true).PlayCount ++;
      ///         file.Save ();
      ///   }
      /// }
      ///    </code>
      ///    <code lang="C++">
      /// #using &lt;System.dll>
      /// #using &lt;taglib-sharp.dll>
      ///
      /// using System;
      /// using TagLib;
      /// using TagLib::Id3v2;
      ///
      /// public ref class TrackUtil abstract sealed
      /// {
      /// public:
      ///   static int GetPlayCount (String^ filename)
      ///   {
      ///         File^ file = File.Create (filename, ReadStyle.None);
      ///         Id3v2::Tag^ tag = dynamic_cast&lt;Id3v2::Tag^> (file.GetTag (TagTypes::Id3v2, false));
      ///         if (tag == null)
      ///               return 0;
      ///         
      ///         PlayCountFrame^ frame = PlayCountFrame::Get (tag, false);
      ///         if (frame == null)
      ///               return 0;
      ///
      ///         return frame->PlayCount;
      ///   }
      ///   
      ///   static void IncrementPlayCount (String^ filename)
      ///   {
      ///         File^ file = File::Create (filename, ReadStyle::None);
      ///         Id3v2.Tag^ tag = dynamic_cast&lt;Id3v2::Tag^> (file.GetTag (TagTypes::Id3v2, true));
      ///         if (tag == null)
      ///               return;
      ///         
      ///         PlayCountFrame::Get (tag, true)->PlayCount ++;
      ///         file->Save ();
      ///   }
      /// }
      ///    </code>
      ///    <code lang="VB">
      /// Imports TagLib
      /// Imports TagLib.Id3v2
      ///
      /// Public Shared Class TrackUtil
      ///   Public Shared Sub GetPlayCount (filename As String) As Integer
      ///         Dim file As File = File.Create (filename, ReadStyle.None)
      ///         Dim tag As Id3v2.Tag = file.GetTag (TagTypes.Id3v2, False)
      ///         If tag Is Nothing Then Return 0
      ///         
      ///         Dim frame As PlayCountFrame = PlayCountFrame.Get (tag, False)
      ///         If frame Is Nothing Then Return 0
      ///
      ///         Return frame.PlayCount
      ///   End Sub
      ///
      ///   Public Shared Sub IncrementPlayCount (filename As String)
      ///         Dim file As File = File.Create (filename, ReadStyle.None)
      ///         Dim tag As Id3v2.Tag = file.GetTag (TagTypes.Id3v2, True)
      ///         If tag Is Nothing Then Exit Sub
      ///         
      ///         PlayCountFrame.Get (tag, True).PlayCount += 1
      ///         file.Save ()
      ///   End Sub
      /// End Class
      ///    </code>
      ///    <code lang="Boo">
      /// import TagLib
      /// import TagLib.Id3v2
      /// 
      /// public static class TrackUtil:
      ///   static def GetPlayCount (filename as string) as int:
      ///         file As File = File.Create (filename, ReadStyle.None)
      ///         tag as Id3v2.Tag = file.GetTag (TagTypes.Id3v2, false)
      ///         if tag == null:
      ///               return 0
      ///         
      ///         frame as PlayCountFrame = PlayCountFrame.Get (tag, false)
      ///         if frame == null:
      ///               return 0
      ///
      ///         return frame.PlayCount
      ///
      ///   static def IncrementPlayCount (filename as string):
      ///         file as File = File.Create (filename, ReadStyle.None)
      ///         tag as Id3v2.Tag = file.GetTag (TagTypes.Id3v2, True)
      ///         if tag == null:
      ///               return
      ///         
      ///         PlayCountFrame.Get (tag, true).PlayCount ++
      ///         file.Save ()
      ///    </code>
      /// </example>
00160       public class PlayCountFrame : Frame
      {
            #region Private Properties
            
            /// <summary>
            ///    Contains the total number of times the file has been
            ///    played.
            /// </summary>
00168             private ulong play_count = 0;
            
            #endregion
            
            
            
            #region Constructors
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PlayCountFrame" /> with a count of zero.
            /// </summary>
            /// <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>
00185             public PlayCountFrame () : base (FrameType.PCNT, 4)
            {
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PlayCountFrame" /> 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>
00202             public PlayCountFrame (ByteVector data, byte version)
                  : base (data, version)
            {
                  SetData (data, 0, version, true);
            }
            
            /// <summary>
            ///    Constructs and initializes a new instance of <see
            ///    cref="PlayCountFrame" /> 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>
00229             protected internal PlayCountFrame (ByteVector data, int offset,
                                               FrameHeader header,
                                               byte version) : base(header)
            {
                  SetData (data, offset, version, false);
            }
            
            #endregion
            
            
            
            #region Public Properties
            
            /// <summary>
            ///    Gets and sets the play count of the current instance.
            /// </summary>
            /// <value>
            ///    A <see cref="ulong" /> containing the play count of the
            ///    current instance.
            /// </value>
00249             public ulong PlayCount {
                  get {return play_count;}
                  set {play_count = value;}
            }
            
            #endregion
            
            
            
            #region Public Static Methods
            
            /// <summary>
            ///    Gets a play count frame from a 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="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="PlayCountFrame" /> object containing the
            ///    matching frame, or <see langword="null" /> if a match
            ///    wasn't found and <paramref name="create" /> is <see
            ///    langword="false" />.
            /// </returns>
00277             public static PlayCountFrame Get (Tag tag, bool create)
            {
                  PlayCountFrame pcnt;
                  foreach (Frame frame in tag) {
                        pcnt = frame as PlayCountFrame;
                        
                        if (pcnt != null)
                              return pcnt;
                  }
                  
                  if (!create)
                        return null;
                  
                  pcnt = new PlayCountFrame ();
                  tag.AddFrame (pcnt);
                  return pcnt;
            }
            
            #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>
00313             protected override void ParseFields (ByteVector data, byte version)
            {
                  play_count = data.ToULong ();
            }
            
            /// <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>
00330             protected override ByteVector RenderFields (byte version)
            {
                  ByteVector data = ByteVector.FromULong (play_count);
                  while (data.Count > 4 && data [0] == 0)
                        data.RemoveAt (0);
                  
                  return data;
            }
            
#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>
00352             public override Frame Clone ()
            {
                  PlayCountFrame frame = new PlayCountFrame ();
                  frame.play_count = play_count;
                  return frame;
            }
            
#endregion
      }
}

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