Fix IPTC tags written on jpg files that contains non-English characters can't be correctly displayed on external apps #2212

src/ImageSharp/Metadata/Profiles/IPTC/IptcProfile.cs

@@ -6,6 +6,7 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Text;
+using SixLabors.ImageSharp.Metadata.Profiles.IPTC;
 
 namespace SixLabors.ImageSharp.Metadata.Profiles.Iptc
 {
@@ -20,6 +21,11 @@ public sealed class IptcProfile : IDeepCloneable<IptcProfile>
 
         private const uint MaxStandardDataTagSize = 0x7FFF;
 
+        /// <summary>
+        /// 1:90 Coded Character Set.
+        /// </summary>
+        private const byte IptcEnvelopeCodedCharacterSet = 0x5A;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="IptcProfile"/> class.
         /// </summary>
@@ -64,6 +70,11 @@ private IptcProfile(IptcProfile other)
             }
         }
 
+        /// <summary>
+        /// Gets a byte array marking that UTF-8 encoding is used in application records.
+        /// </summary>
+        private static ReadOnlySpan<byte> CodedCharacterSetUtf8Value => new byte[] { 0x1B, 0x25, 0x47 }; // Uses C#'s optimization to refer to the data segment in the assembly directly, no allocation occurs.
+
         /// <summary>
         /// Gets the byte data of the IPTC profile.
         /// </summary>
@@ -194,6 +205,17 @@ public void SetValue(IptcTag tag, Encoding encoding, string value, bool strict =
             this.values.Add(new IptcValue(tag, encoding, value, strict));
         }
 
+        /// <summary>
+        /// Sets the value of the specified tag.
+        /// </summary>
+        /// <param name="tag">The tag of the iptc value.</param>
+        /// <param name="value">The value.</param>
+        /// <param name="strict">
+        /// Indicates if length restrictions from the specification should be followed strictly.
+        /// Defaults to true.
+        /// </param>
+        public void SetValue(IptcTag tag, string value, bool strict = true) => this.SetValue(tag, Encoding.UTF8, value, strict);
+
         /// <summary>
         /// Makes sure the datetime is formatted according to the iptc specification.
         /// <example>
@@ -219,17 +241,6 @@ public void SetDateTimeValue(IptcTag tag, DateTimeOffset dateTimeOffset)
             this.SetValue(tag, Encoding.UTF8, formattedDate);
         }
 
-        /// <summary>
-        /// Sets the value of the specified tag.
-        /// </summary>
-        /// <param name="tag">The tag of the iptc value.</param>
-        /// <param name="value">The value.</param>
-        /// <param name="strict">
-        /// Indicates if length restrictions from the specification should be followed strictly.
-        /// Defaults to true.
-        /// </param>
-        public void SetValue(IptcTag tag, string value, bool strict = true) => this.SetValue(tag, Encoding.UTF8, value, strict);
-
         /// <summary>
         /// Updates the data of the profile.
         /// </summary>
@@ -241,12 +252,25 @@ public void UpdateData()
                 length += value.Length + 5;
             }
 
+            bool hasValuesInUtf8 = this.HasValuesInUtf8();
+
+            if (hasValuesInUtf8)
+            {
+                // Additional length for UTF-8 Tag.
+                length += 5 + CodedCharacterSetUtf8Value.Length;
+            }
+
             this.Data = new byte[length];
+            int offset = 0;
+            if (hasValuesInUtf8)
+            {
+                // Write Envelope Record.
+                offset = this.WriteRecord(offset, CodedCharacterSetUtf8Value, IptcRecordNumber.Envelope, IptcEnvelopeCodedCharacterSet);
+            }
 
-            int i = 0;
             foreach (IptcValue value in this.Values)
             {
-                // Standard DataSet Tag
+                // Write Application Record.
                 // +-----------+----------------+---------------------------------------------------------------------------------+
                 // | Octet Pos | Name           | Description                                                                     |
                 // +==========-+================+=================================================================================+
@@ -263,17 +287,26 @@ public void UpdateData()
                 // |           | Octet Count    | the following data field(32767 or fewer octets). Note that the value of bit 7 of|
                 // |           |                | octet 4(most significant bit) always will be 0.                                 |
                 // +-----------+----------------+---------------------------------------------------------------------------------+
-                this.Data[i++] = IptcTagMarkerByte;
-                this.Data[i++] = 2;
-                this.Data[i++] = (byte)value.Tag;
-                this.Data[i++] = (byte)(value.Length >> 8);
-                this.Data[i++] = (byte)value.Length;
-                if (value.Length > 0)
-                {
-                    Buffer.BlockCopy(value.ToByteArray(), 0, this.Data, i, value.Length);
-                    i += value.Length;
-                }
+                offset = this.WriteRecord(offset, value.ToByteArray(), IptcRecordNumber.Application, (byte)value.Tag);
+            }
+        }
+
+        private int WriteRecord(int offset, ReadOnlySpan<byte> recordData, IptcRecordNumber recordNumber, byte recordBinaryRepresentation)
+        {
+            Span<byte> data = this.Data.AsSpan(offset, 5);
+            data[0] = IptcTagMarkerByte;
+            data[1] = (byte)recordNumber;
+            data[2] = recordBinaryRepresentation;
+            data[3] = (byte)(recordData.Length >> 8);
+            data[4] = (byte)recordData.Length;
+            offset += 5;
+            if (recordData.Length > 0)
+            {
+                recordData.CopyTo(this.Data.AsSpan(offset));
+                offset += recordData.Length;
             }
+
+            return offset;
         }
 
         private void Initialize()
@@ -298,6 +331,7 @@ private void Initialize()
                 bool isValidRecordNumber = recordNumber is >= 1 and <= 9;
                 var tag = (IptcTag)this.Data[offset++];
                 bool isValidEntry = isValidTagMarker && isValidRecordNumber;
+                bool isApplicationRecord = recordNumber == (byte)IptcRecordNumber.Application;
 
                 uint byteCount = BinaryPrimitives.ReadUInt16BigEndian(this.Data.AsSpan(offset, 2));
                 offset += 2;
@@ -307,15 +341,32 @@ private void Initialize()
                     break;
                 }
 
-                if (isValidEntry && byteCount > 0 && (offset <= this.Data.Length - byteCount))
+                if (isValidEntry && isApplicationRecord && byteCount > 0 && (offset <= this.Data.Length - byteCount))
                 {
-                    var iptcData = new byte[byteCount];
+                    byte[] iptcData = new byte[byteCount];
                     Buffer.BlockCopy(this.Data, offset, iptcData, 0, (int)byteCount);
                     this.values.Add(new IptcValue(tag, iptcData, false));
                 }
 
                 offset += (int)byteCount;
             }
         }
+
+        /// <summary>
+        /// Gets if any value has UTF-8 encoding.
+        /// </summary>
+        /// <returns>true if any value has UTF-8 encoding.</returns>
+        private bool HasValuesInUtf8()
+        {
+            foreach (IptcValue value in this.values)
+            {
+                if (value.Encoding == Encoding.UTF8)
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
     }
 }

src/ImageSharp/Metadata/Profiles/IPTC/IptcRecordNumber.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Metadata.Profiles.IPTC
+{
+    /// <summary>
+    /// Enum for the different record types of a IPTC value.
+    /// </summary>
+    internal enum IptcRecordNumber : byte
+    {
+        /// <summary>
+        /// A Envelope Record.
+        /// </summary>
+        Envelope = 0x01,
+
+        /// <summary>
+        /// A Application Record.
+        /// </summary>
+        Application = 0x02
+    }
+}

tests/ImageSharp.Tests/Formats/Jpg/JpegEncoderTests.Metadata.cs

@@ -38,8 +38,10 @@ public void Encode_PreservesIptcProfile()
         {
             // arrange
             using var input = new Image<Rgba32>(1, 1);
-            input.Metadata.IptcProfile = new IptcProfile();
-            input.Metadata.IptcProfile.SetValue(IptcTag.Byline, "unit_test");
+            var expectedProfile = new IptcProfile();
+            expectedProfile.SetValue(IptcTag.Country, "ESPAÑA");
+            expectedProfile.SetValue(IptcTag.City, "unit-test-city");
+            input.Metadata.IptcProfile = expectedProfile;
 
             // act
             using var memStream = new MemoryStream();
@@ -50,7 +52,7 @@ public void Encode_PreservesIptcProfile()
             using var output = Image.Load<Rgba32>(memStream);
             IptcProfile actual = output.Metadata.IptcProfile;
             Assert.NotNull(actual);
-            IEnumerable<IptcValue> values = input.Metadata.IptcProfile.Values;
+            IEnumerable<IptcValue> values = expectedProfile.Values;
             Assert.Equal(values, actual.Values);
         }
 

tests/ImageSharp.Tests/Metadata/Profiles/IPTC/IptcProfileTests.cs

@@ -15,9 +15,9 @@ namespace SixLabors.ImageSharp.Tests.Metadata.Profiles.IPTC
 {
     public class IptcProfileTests
     {
-        private static JpegDecoder JpegDecoder => new JpegDecoder() { IgnoreMetadata = false };
+        private static JpegDecoder JpegDecoder => new() { IgnoreMetadata = false };
 
-        private static TiffDecoder TiffDecoder => new TiffDecoder() { IgnoreMetadata = false };
+        private static TiffDecoder TiffDecoder => new() { IgnoreMetadata = false };
 
         public static IEnumerable<object[]> AllIptcTags()
         {
@@ -27,6 +27,22 @@ public static IEnumerable<object[]> AllIptcTags()
             }
         }
 
+        [Fact]
+        public void IptcProfile_WithUtf8Data_WritesEnvelopeRecord_Works()
+        {
+            // arrange
+            var profile = new IptcProfile();
+            profile.SetValue(IptcTag.City, "ESPAÑA");
+            profile.UpdateData();
+            byte[] expectedEnvelopeData = { 28, 1, 90, 0, 3, 27, 37, 71 };
+
+            // act
+            byte[] profileBytes = profile.Data;
+
+            // assert
+            Assert.True(profileBytes.AsSpan(0, 8).SequenceEqual(expectedEnvelopeData));
+        }
+
         [Theory]
         [MemberData(nameof(AllIptcTags))]
         public void IptcProfile_SetValue_WithStrictEnabled_Works(IptcTag tag)