Don't skip data read on animation and frame control chunks

Author: JimBobSquarePants

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -1871,8 +1871,13 @@ private bool TryReadChunk(Span<byte> buffer, out PngChunk chunk)
         PngChunkType type = this.ReadChunkType(buffer);
 
         // If we're reading color metadata only we're only interested in the IHDR and tRNS chunks.
-        // We can skip all other chunk data in the stream for better performance.
-        if (this.colorMetadataOnly && type != PngChunkType.Header && type != PngChunkType.Transparency && type != PngChunkType.Palette)
+        // We can skip most other chunk data in the stream for better performance.
+        if (this.colorMetadataOnly &&
+            type != PngChunkType.Header &&
+            type != PngChunkType.Transparency &&
+            type != PngChunkType.Palette &&
+            type != PngChunkType.AnimationControl &&
+            type != PngChunkType.FrameControl)
         {
             chunk = new PngChunk(length, type);
             return true;

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.IO;
 using System.Runtime.Intrinsics.X86;
 using Microsoft.DotNet.RemoteExecutor;
 using SixLabors.ImageSharp.Formats;
@@ -665,4 +666,11 @@ public void Binary_PrematureEof()
         Assert.True(eofHitCounter.EofHitCount <= 3);
         Assert.Equal(new Size(200, 120), eofHitCounter.Image.Size);
     }
+
+    [Fact]
+    public void Decode_Issue2666()
+    {
+        string path = Path.GetFullPath(Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, TestImages.Png.Issue2666));
+        using Image image = Image.Load(path);
+    }
 }

tests/ImageSharp.Tests/TestImages.cs

@@ -73,6 +73,7 @@ public static class Png
         public const string DisposeBackgroundRegion = "Png/animated/15-dispose-background-region.png";
         public const string DisposePreviousFirst = "Png/animated/12-dispose-prev-first.png";
         public const string BlendOverMultiple = "Png/animated/21-blend-over-multiple.png";
+        public const string Issue2666 = "Png/Issues/Issue_2666.png";
 
         // Filtered test images from http://www.schaik.com/pngsuite/pngsuite_fil_png.html
         public const string Filter0 = "Png/filter0.png";