From a8086f135277922b0ae2edd2a90c4793a08c1d2b Mon Sep 17 00:00:00 2001
From: Tomasz Cielecki <tci@trackman.com>
Date: Tue, 3 Oct 2023 21:00:31 +0200
Subject: [PATCH] Change ExifTag TimeZoneOffset to Signed Short

---
 .../Profiles/Exif/Tags/ExifTag.LongArray.cs   |  5 ----
 .../Exif/Tags/ExifTag.SignedShortArray.cs     | 13 +++++++++++
 .../Exif/Values/ExifSignedShortArray.cs       |  5 ++++
 .../Profiles/Exif/Values/ExifValues.cs        |  5 ++--
 .../Profiles/Exif/Values/ExifValuesTests.cs   | 23 +++++++++++++++++--
 5 files changed, 42 insertions(+), 9 deletions(-)
 create mode 100644 src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.SignedShortArray.cs

diff --git a/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.LongArray.cs b/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.LongArray.cs
index 741df50f2d..4767ca852e 100644
--- a/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.LongArray.cs
+++ b/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.LongArray.cs
@@ -56,11 +56,6 @@ public abstract partial class ExifTag
     /// </summary>
     public static ExifTag<uint[]> IntergraphRegisters { get; } = new ExifTag<uint[]>(ExifTagValue.IntergraphRegisters);
 
-    /// <summary>
-    /// Gets the TimeZoneOffset exif tag.
-    /// </summary>
-    public static ExifTag<uint[]> TimeZoneOffset { get; } = new ExifTag<uint[]>(ExifTagValue.TimeZoneOffset);
-
     /// <summary>
     /// Gets the offset to child IFDs exif tag.
     /// </summary>
diff --git a/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.SignedShortArray.cs b/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.SignedShortArray.cs
new file mode 100644
index 0000000000..d6a9205143
--- /dev/null
+++ b/src/ImageSharp/Metadata/Profiles/Exif/Tags/ExifTag.SignedShortArray.cs
@@ -0,0 +1,13 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+namespace SixLabors.ImageSharp.Metadata.Profiles.Exif;
+
+/// <content/>
+public abstract partial class ExifTag
+{
+    /// <summary>
+    /// Gets the TimeZoneOffset exif tag.
+    /// </summary>
+    public static ExifTag<short[]> TimeZoneOffset { get; } = new ExifTag<short[]>(ExifTagValue.TimeZoneOffset);
+}
diff --git a/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifSignedShortArray.cs b/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifSignedShortArray.cs
index 8023fb8bca..206417f667 100644
--- a/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifSignedShortArray.cs
+++ b/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifSignedShortArray.cs
@@ -5,6 +5,11 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif;
 
 internal sealed class ExifSignedShortArray : ExifArrayValue<short>
 {
+    public ExifSignedShortArray(ExifTag<short[]> tag)
+        : base(tag)
+    {
+    }
+
     public ExifSignedShortArray(ExifTagValue tag)
         : base(tag)
     {
diff --git a/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifValues.cs b/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifValues.cs
index 8aa54c3a40..a4217fe026 100644
--- a/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifValues.cs
+++ b/src/ImageSharp/Metadata/Profiles/Exif/Values/ExifValues.cs
@@ -144,8 +144,6 @@ internal static partial class ExifValues
                 return new ExifLongArray(ExifTag.StripRowCounts);
             case ExifTagValue.IntergraphRegisters:
                 return new ExifLongArray(ExifTag.IntergraphRegisters);
-            case ExifTagValue.TimeZoneOffset:
-                return new ExifLongArray(ExifTag.TimeZoneOffset);
             case ExifTagValue.SubIFDs:
                 return new ExifLongArray(ExifTag.SubIFDs);
 
@@ -417,6 +415,9 @@ internal static partial class ExifValues
             case ExifTagValue.Decode:
                 return new ExifSignedRationalArray(ExifTag.Decode);
 
+            case ExifTagValue.TimeZoneOffset:
+                return new ExifSignedShortArray(ExifTag.TimeZoneOffset);
+
             case ExifTagValue.ImageDescription:
                 return new ExifString(ExifTag.ImageDescription);
             case ExifTagValue.Make:
diff --git a/tests/ImageSharp.Tests/Metadata/Profiles/Exif/Values/ExifValuesTests.cs b/tests/ImageSharp.Tests/Metadata/Profiles/Exif/Values/ExifValuesTests.cs
index 1adb7bd556..bf1ef1a9b0 100644
--- a/tests/ImageSharp.Tests/Metadata/Profiles/Exif/Values/ExifValuesTests.cs
+++ b/tests/ImageSharp.Tests/Metadata/Profiles/Exif/Values/ExifValuesTests.cs
@@ -70,8 +70,7 @@ public class ExifValuesTests
         { ExifTag.JPEGDCTables },
         { ExifTag.JPEGACTables },
         { ExifTag.StripRowCounts },
-        { ExifTag.IntergraphRegisters },
-        { ExifTag.TimeZoneOffset }
+        { ExifTag.IntergraphRegisters }
     };
 
     public static TheoryData<ExifTag> NumberTags => new TheoryData<ExifTag>
@@ -235,6 +234,11 @@ public class ExifValuesTests
         { ExifTag.Decode }
     };
 
+    public static TheoryData<ExifTag> SignedShortArrayTags => new TheoryData<ExifTag>
+    {
+        { ExifTag.TimeZoneOffset }
+    };
+
     public static TheoryData<ExifTag> StringTags => new TheoryData<ExifTag>
     {
         { ExifTag.ImageDescription },
@@ -559,6 +563,21 @@ public void ExifSignedRationalArrayTests(ExifTag tag)
         Assert.Equal(expected, typed.Value);
     }
 
+
+    [Theory]
+    [MemberData(nameof(SignedShortArrayTags))]
+    public void ExifSignedShortArrayTests(ExifTag tag)
+    {
+        short[] expected = new short[] { 21, 42 };
+        ExifValue value = ExifValues.Create(tag);
+
+        Assert.False(value.TrySetValue(expected.ToString()));
+        Assert.True(value.TrySetValue(expected));
+
+        var typed = (ExifSignedShortArray)value;
+        Assert.Equal(expected, typed.Value);
+    }
+
     [Theory]
     [MemberData(nameof(StringTags))]
     public void ExifStringTests(ExifTag tag)