try improve reading ext

values

src/ImageSharp/Formats/Tiff/Ifd/DirectoryReader.cs

@@ -18,10 +18,6 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
         private ulong nextIfdOffset;
 
-        // used for sequential read big values (actual for multiframe big files)
-        // todo: different tags can link to the same data (stream offset) - investigate
-        private readonly SortedList<ulong, Action> lazyLoaders = new SortedList<ulong, Action>(new DuplicateKeyComparer<ulong>());
-
         public DirectoryReader(Stream stream) => this.stream = stream;
 
         /// <summary>
@@ -68,23 +64,28 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             var readers = new List<EntryReader>();
             while (this.nextIfdOffset != 0 && this.nextIfdOffset < (ulong)this.stream.Length)
             {
-                var reader = new EntryReader(this.stream, this.ByteOrder, this.lazyLoaders);
+                var reader = new EntryReader(this.stream, this.ByteOrder);
                 reader.ReadTags(isBigTiff, this.nextIfdOffset);
 
-                this.nextIfdOffset = reader.NextIfdOffset;
+                if (reader.ExtTags.Count > 0)
+                {
+                    reader.ExtTags.Sort((t1, t2) => t1.offset.CompareTo(t2.offset));
 
-                readers.Add(reader);
+                    if (reader.ExtTags[0].offset < reader.NextIfdOffset)
-            }
+                    {
+                        // this means that most likely all elements are placed  before next IFD
+                        reader.ReadExtValues();
+                    }
+                }
 
-            // Sequential reading big values.
+                this.nextIfdOffset = reader.NextIfdOffset;
-            foreach (Action loader in this.lazyLoaders.Values)
+                readers.Add(reader);
-            {
-                loader();
             }
 
             var list = new List<ExifProfile>(readers.Count);
             foreach (EntryReader reader in readers)
             {
+                reader.ReadExtValues();
                 var profile = new ExifProfile(reader.Values, reader.InvalidTags);
                 list.Add(profile);
             }

src/ImageSharp/Formats/Tiff/Ifd/EntryReader.cs

@@ -12,13 +12,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 {
     internal class EntryReader : BaseExifReader
     {
-        private readonly SortedList<ulong, Action> lazyLoaders;
+        public EntryReader(Stream stream, ByteOrder byteOrder)
-
-        public EntryReader(Stream stream, ByteOrder byteOrder, SortedList<ulong, Action> lazyLoaders)
             : base(stream)
         {
             this.IsBigEndian = byteOrder == ByteOrder.BigEndian;
-            this.lazyLoaders = lazyLoaders;
         }
 
         public List<IExifValue> Values { get; } = new List<IExifValue>();
@@ -43,8 +40,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff
             }
         }
 
-        protected override void RegisterExtLoader(ulong offset, Action reader) =>
+        public void ReadExtValues() => this.ReadExtValues(this.Values);
-            this.lazyLoaders.Add(offset, reader);
     }
 
     internal class HeaderReader : BaseExifReader
@@ -81,7 +77,5 @@ namespace SixLabors.ImageSharp.Formats.Tiff
 
             TiffThrowHelper.ThrowInvalidHeader();
         }
-
-        protected override void RegisterExtLoader(ulong offset, Action reader) => throw new NotSupportedException();
     }
 }

src/ImageSharp/Metadata/Profiles/Exif/ExifReader.cs

@@ -14,8 +14,6 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
 {
     internal class ExifReader : BaseExifReader
     {
-        private readonly List<Action> loaders = new List<Action>();
-
         public ExifReader(byte[] exifData)
             : base(new MemoryStream(exifData ?? throw new ArgumentNullException(nameof(exifData))))
         {
@@ -41,22 +39,16 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
 
             uint ifdOffset = this.ReadUInt32();
             this.ReadValues(values, ifdOffset);
+            this.ReadExtValues(values);
 
             uint thumbnailOffset = this.ReadUInt32();
             this.GetThumbnail(thumbnailOffset);
 
             this.ReadSubIfd(values);
 
-            foreach (Action loader in this.loaders)
-            {
-                loader();
-            }
-
             return values;
         }
 
-        protected override void RegisterExtLoader(ulong offset, Action loader) => this.loaders.Add(loader);
-
         private void GetThumbnail(uint offset)
         {
             if (offset == 0)
@@ -121,7 +113,17 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
 
         public bool IsBigEndian { get; protected set; }
 
-        protected abstract void RegisterExtLoader(ulong offset, Action loader);
+        public List<(ulong offset, ExifDataType dataType, ulong numberOfComponents, ExifValue exif)> ExtTags { get; } = new ();
+
+        protected void ReadExtValues(List<IExifValue> values)
+        {
+            foreach ((ulong offset, ExifDataType dataType, ulong numberOfComponents, ExifValue exif) tag in this.ExtTags)
+            {
+                this.ReadExtValue(values, tag);
+            }
+
+            this.ExtTags.Clear();
+        }
 
         /// <summary>
         /// Reads the values to the values collection.
@@ -173,6 +175,18 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
             }
         }
 
+        protected void ReadExtValue(IList<IExifValue> values, (ulong offset, ExifDataType dataType, ulong numberOfComponents, ExifValue exif) tag)
+        {
+            ulong size = tag.numberOfComponents * ExifDataTypes.GetSize(tag.dataType);
+            byte[] dataBuffer = new byte[size];
+            this.Seek(tag.offset);
+            if (this.TryReadSpan(dataBuffer))
+            {
+                object value = this.ConvertValue(tag.dataType, dataBuffer, tag.numberOfComponents);
+                this.Add(values, tag.exif, value);
+            }
+        }
+
         protected void ReadSubIfd64(List<IExifValue> values)
         {
             if (this.exifOffset != 0)
@@ -375,21 +389,11 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
                     return;
                 }
 
-                this.RegisterExtLoader(newOffset, () =>
+                this.ExtTags.Add((newOffset, dataType, numberOfComponents, exifValue));
-                {
-                    byte[] dataBuffer = new byte[size];
-                    this.Seek(newOffset);
-                    if (this.TryReadSpan(dataBuffer))
-                    {
-                        object value = this.ConvertValue(dataType, dataBuffer, numberOfComponents);
-                        this.Add(values, exifValue, value);
-                    }
-                });
             }
             else
             {
                 object value = this.ConvertValue(dataType, this.offsetBuffer, numberOfComponents);
-
                 this.Add(values, exifValue, value);
             }
         }
@@ -465,16 +469,7 @@ namespace SixLabors.ImageSharp.Metadata.Profiles.Exif
                     return;
                 }
 
-                this.RegisterExtLoader(newOffset, () =>
+                this.ExtTags.Add((newOffset, dataType, numberOfComponents, exifValue));
-                {
-                    byte[] dataBuffer = new byte[size];
-                    this.Seek(newOffset);
-                    if (this.TryReadSpan(dataBuffer))
-                    {
-                        object value = this.ConvertValue(dataType, dataBuffer, numberOfComponents);
-                        this.Add(values, exifValue, value);
-                    }
-                });
             }
             else
             {