Audio Id3v2 add support for the Tag Length (#284)

* Id3v2 - add support for the Tag Length

* AddLendthTagId3v2 fix test formatting

* audioId3v2 - fix comment for length

Co-authored-by: LORICARROLLA016\lcarroll <[email protected]>

Author: morganalori

src/TaglibSharp.Tests/TaggingFormats/Id3V2Test.cs

@@ -996,6 +996,34 @@ public void TestISRC ()
 			}
 		}
 
+		[Test]
+		public void TestLength ()
+		{
+			Tag tag = new Tag ();
+			for (byte version = 2; version <= 4; version++) {
+				tag.Version = version;
+
+				TagTestWithSave (ref tag, delegate (Tag t, string m) {
+					Assert.IsTrue (t.IsEmpty, "Initial (IsEmpty): " + m);
+					Assert.IsNull (t.Length, "Initial (Null): " + m);
+				});
+
+				tag.Length = val_sing;
+
+				TagTestWithSave (ref tag, delegate (Tag t, string m) {
+					Assert.IsFalse (t.IsEmpty, "Value Set (!IsEmpty): " + m);
+					Assert.AreEqual (val_sing, t.Length, "Value Set (!Null): " + m);
+				});
+
+				tag.Length = string.Empty;
+
+				TagTestWithSave (ref tag, delegate (Tag t, string m) {
+					Assert.IsTrue (t.IsEmpty, "Value Cleared (IsEmpty): " + m);
+					Assert.IsNull (t.Length, "Value Cleared (Null): " + m);
+				});
+			}
+		}
+
 		[Test]
 		public void TestRemixedBy ()
 		{
@@ -1049,6 +1077,7 @@ public void TestClear ()
 				InitialKey = "K",
 				Publisher = "L",
 				ISRC = "M",
+				Length = "L",
 				RemixedBy = "N"
 			};
 
@@ -1078,6 +1107,7 @@ public void TestClear ()
 			Assert.IsNull (tag.InitialKey, "InitialKey");
 			Assert.IsNull (tag.Publisher, "Publisher");
 			Assert.IsNull (tag.ISRC, "ISRC");
+			Assert.IsNull (tag.Length, "Length");
 			Assert.IsNull (tag.RemixedBy, "RemixedBy");
 		}
 

src/TaglibSharp/CombinedTag.cs

@@ -1980,6 +1980,45 @@ public override string ISRC {
 			}
 		}
 
+		/// <summary>
+		///    Gets and sets the length of the media
+		///    represented by the current instance.
+		/// </summary>
+		/// <value>
+		///    A <see cref="string" /> object containing the 
+		///    length of the media represented by the current
+		///    instance or <see langword="null" /> if no value present.
+		/// </value>
+		/// <remarks>
+		///    <para>When getting the value, the child tags are looped
+		///    through in order and the first non-<see langword="null" />
+		///    value is returned.</para>
+		///    <para>When setting the value, it is stored in each child
+		///    tag.</para>
+		/// </remarks>
+		/// <seealso cref="Tag.Length" />
+		public override string Length {
+			get {
+				foreach (Tag tag in tags) {
+					if (tag == null)
+						continue;
+
+					string value = tag.Length;
+
+					if (value != null)
+						return value;
+				}
+
+				return null;
+			}
+
+			set {
+				foreach (Tag tag in tags)
+					if (tag != null)
+						tag.Length = value;
+			}
+		}
+
 		/// <summary>
 		///    Gets whether or not the current instance is empty.
 		/// </summary>

src/TaglibSharp/Id3v2/FrameTypes.cs

@@ -65,6 +65,7 @@ static class FrameType
 		public static readonly ReadOnlyByteVector TIT3 = "TIT3";
 		public static readonly ReadOnlyByteVector TIME = "TIME";
 		public static readonly ReadOnlyByteVector TKEY = "TKEY";
+		public static readonly ReadOnlyByteVector TLEN = "TLEN"; // audio length
 		public static readonly ReadOnlyByteVector TMCL = "TMCL";
 		public static readonly ReadOnlyByteVector TOLY = "TOLY";
 		public static readonly ReadOnlyByteVector TOPE = "TOPE";

src/TaglibSharp/Id3v2/Tag.cs

@@ -2279,6 +2279,25 @@ public override string ISRC {
 			set { SetTextFrame (FrameType.TSRC, value); }
 		}
 
+		/// <summary>
+		///    Gets and sets the length of the media represented
+		///    by the current instance.
+		/// </summary>
+		/// <value>
+		///    A <see cref="string" /> object containing the length of
+		///    the media represented by the current instance or <see
+		///    langword="null" /> if no value is present.
+		/// </value>
+		/// <remarks>
+		///    <para>This field represents the label or length of the album the
+		///    media belongs to. </para>
+		///    <para>For example, "00:15:00".</para>
+		/// </remarks>
+		public override string Length {
+			get { return GetTextAsString (FrameType.TLEN); }
+			set { SetTextFrame (FrameType.TLEN, value); }
+		}
+
 		/// <summary>
 		///    Gets and sets a collection of pictures associated with
 		///    the media represented by the current instance.

src/TaglibSharp/Tag.cs

@@ -1059,6 +1059,25 @@ public virtual string ISRC {
 			set { }
 		}
 
+		/// <summary>
+		///    Gets and sets the Length of the media represented
+		///    by the current instance.
+		/// </summary>
+		/// <value>
+		///    A <see cref="string" /> object containing the length of
+		///    the media represented by the current instance or <see
+		///    langword="null" /> if no value is present.
+		/// </value>
+		/// <remarks>
+		///    <para>This field represents the label or length of the album the
+		///    media belongs to. </para>
+		///    <para>For example, "00:15:00".</para>
+		/// </remarks>
+		public virtual string Length {
+			get { return null; }
+			set { }
+		}
+
 		/// <summary>
 		///    Gets and sets a collection of pictures associated with
 		///    the media represented by the current instance.