Review changes

src/ImageSharp/Formats/Tiff/Compression/Decompressors/CcittReferenceScanline.cs

@@ -48,7 +48,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         /// <returns>Position of b1.</returns>
         public int FindB1(int a0, byte a0Byte)
         {
-            if (this.scanLine.IsEmpty)
+            if (this.IsEmpty)
             {
                 return this.FindB1ForImaginaryWhiteLine(a0, a0Byte);
             }
@@ -63,7 +63,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         /// <returns>Position of b1.</returns>
         public int FindB2(int b1)
         {
-            if (this.scanLine.IsEmpty)
+            if (this.IsEmpty)
             {
                 return this.FindB2ForImaginaryWhiteLine();
             }

src/ImageSharp/Formats/Tiff/Compression/Decompressors/CcittTwoDimensionalCodeType.cs

@@ -3,30 +3,71 @@
 
 namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
 {
+    /// <summary>
+    /// Enum for the different two dimensional code words for the ccitt fax compression.
+    /// </summary>
     internal enum CcittTwoDimensionalCodeType
     {
+        /// <summary>
+        /// No valid code word was read.
+        /// </summary>
         None = 0,
 
+        /// <summary>
+        /// Pass mode: This mode is identified when the position of b2 lies to the left of a1.
+        /// </summary>
         Pass = 1,
 
+        /// <summary>
+        /// Indicates horizontal mode.
+        /// </summary>
         Horizontal = 2,
 
+        /// <summary>
+        /// Vertical 0 code word: relative distance between a1 and b1 is 0.
+        /// </summary>
         Vertical0 = 3,
 
+        /// <summary>
+        /// Vertical r1 code word: relative distance between a1 and b1 is 1, a1 is to the right of b1.
+        /// </summary>
         VerticalR1 = 4,
 
+        /// <summary>
+        /// Vertical r2 code word: relative distance between a1 and b1 is 2, a1 is to the right of b1.
+        /// </summary>
         VerticalR2 = 5,
 
+        /// <summary>
+        /// Vertical r3 code word: relative distance between a1 and b1 is 3, a1 is to the right of b1.
+        /// </summary>
         VerticalR3 = 6,
 
+        /// <summary>
+        /// Vertical l1 code word: relative distance between a1 and b1 is 1, a1 is to the left of b1.
+        /// </summary>
         VerticalL1 = 7,
 
+        /// <summary>
+        /// Vertical l2 code word: relative distance between a1 and b1 is 2, a1 is to the left of b1.
+        /// </summary>
         VerticalL2 = 8,
 
+        /// <summary>
+        /// Vertical l3 code word: relative distance between a1 and b1 is 3, a1 is to the left of b1.
+        /// </summary>
         VerticalL3 = 9,
 
+        /// <summary>
+        /// 1d extensions code word, extension code is used to indicate the change from the current mode to another mode, e.g., another coding scheme.
+        /// Not supported.
+        /// </summary>
         Extensions1D = 10,
 
+        /// <summary>
+        /// 2d extensions code word, extension code is used to indicate the change from the current mode to another mode, e.g., another coding scheme.
+        /// Not supported.
+        /// </summary>
         Extensions2D = 11,
     }
 }

src/ImageSharp/Formats/Tiff/Compression/Decompressors/DeflateTiffCompression.cs

@@ -18,7 +18,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <remarks>
     /// Note that the 'OldDeflate' compression type is identical to the 'Deflate' compression type.
     /// </remarks>
-    internal class DeflateTiffCompression : TiffBaseDecompressor
+    internal sealed class DeflateTiffCompression : TiffBaseDecompressor
     {
         private readonly bool isBigEndian;
 

src/ImageSharp/Formats/Tiff/Compression/Decompressors/LzwTiffCompression.cs

@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using LZW compression.
     /// </summary>
-    internal class LzwTiffCompression : TiffBaseDecompressor
+    internal sealed class LzwTiffCompression : TiffBaseDecompressor
     {
         private readonly bool isBigEndian;
 

src/ImageSharp/Formats/Tiff/Compression/Decompressors/ModifiedHuffmanBitReader.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// Bit reader for data encoded with the modified huffman rle method.
     /// See TIFF 6.0 specification, section 10.
     /// </summary>
-    internal class ModifiedHuffmanBitReader : T4BitReader
+    internal sealed class ModifiedHuffmanBitReader : T4BitReader
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="ModifiedHuffmanBitReader"/> class.

src/ImageSharp/Formats/Tiff/Compression/Decompressors/ModifiedHuffmanTiffCompression.cs

@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using Modified Huffman Compression.
     /// </summary>
-    internal class ModifiedHuffmanTiffCompression : T4TiffCompression
+    internal sealed class ModifiedHuffmanTiffCompression : TiffBaseDecompressor
     {
         private readonly byte whiteValue;
 
@@ -27,13 +27,19 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         /// <param name="bitsPerPixel">The number of bits per pixel.</param>
         /// <param name="photometricInterpretation">The photometric interpretation.</param>
         public ModifiedHuffmanTiffCompression(MemoryAllocator allocator, TiffFillOrder fillOrder, int width, int bitsPerPixel, TiffPhotometricInterpretation photometricInterpretation)
-            : base(allocator, fillOrder, width, bitsPerPixel, FaxCompressionOptions.None, photometricInterpretation)
+            : base(allocator, width, bitsPerPixel)
         {
+            this.FillOrder = fillOrder;
             bool isWhiteZero = photometricInterpretation == TiffPhotometricInterpretation.WhiteIsZero;
             this.whiteValue = (byte)(isWhiteZero ? 0 : 1);
             this.blackValue = (byte)(isWhiteZero ? 1 : 0);
         }
 
+        /// <summary>
+        /// Gets the logical order of bits within a byte.
+        /// </summary>
+        private TiffFillOrder FillOrder { get; }
+
         /// <inheritdoc/>
         protected override void Decompress(BufferedReadStream stream, int byteCount, int stripHeight, Span<byte> buffer)
         {
@@ -81,5 +87,10 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
                 }
             }
         }
+
+        /// <inheritdoc/>
+        protected override void Dispose(bool disposing)
+        {
+        }
     }
 }

src/ImageSharp/Formats/Tiff/Compression/Decompressors/NoneTiffCompression.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <summary>
     /// Class to handle cases where TIFF image data is not compressed.
     /// </summary>
-    internal class NoneTiffCompression : TiffBaseDecompressor
+    internal sealed class NoneTiffCompression : TiffBaseDecompressor
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="NoneTiffCompression" /> class.

src/ImageSharp/Formats/Tiff/Compression/Decompressors/PackBitsTiffCompression.cs

@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using PackBits compression.
     /// </summary>
-    internal class PackBitsTiffCompression : TiffBaseDecompressor
+    internal sealed class PackBitsTiffCompression : TiffBaseDecompressor
     {
         private IMemoryOwner<byte> compressedDataMemory;
 

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T4BitReader.cs

@@ -438,7 +438,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         /// <returns>The value read.</returns>
         protected uint ReadValue(int nBits)
         {
-            Guard.MustBeGreaterThan(nBits, 0, nameof(nBits));
+            DebugGuard.MustBeGreaterThan(nBits, 0, nameof(nBits));
 
             uint v = 0;
             int shift = nBits;

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T4TiffCompression.cs

@@ -12,7 +12,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using CCITT T4 compression.
     /// </summary>
-    internal class T4TiffCompression : TiffBaseDecompressor
+    internal sealed class T4TiffCompression : TiffBaseDecompressor
     {
         private readonly FaxCompressionOptions faxCompressionOptions;
 
@@ -51,7 +51,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
         /// <summary>
         /// Gets the logical order of bits within a byte.
         /// </summary>
-        protected TiffFillOrder FillOrder { get; }
+        private TiffFillOrder FillOrder { get; }
 
         /// <inheritdoc/>
         protected override void Decompress(BufferedReadStream stream, int byteCount, int stripHeight, Span<byte> buffer)

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T6BitReader.cs

@@ -13,7 +13,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// Bit reader for reading CCITT T6 compressed fax data.
     /// See: Facsimile Coding Schemes and Coding Control Functions for Group 4 Facsimile Apparatus, itu-t recommendation t.6
     /// </summary>
-    internal class T6BitReader : T4BitReader
+    internal sealed class T6BitReader : T4BitReader
     {
         private readonly int maxCodeLength = 12;
 

src/ImageSharp/Formats/Tiff/Compression/Decompressors/T6TiffCompression.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Formats.Tiff.Compression.Decompressors
     /// <summary>
     /// Class to handle cases where TIFF image data is compressed using CCITT T6 compression.
     /// </summary>
-    internal class T6TiffCompression : TiffBaseDecompressor
+    internal sealed class T6TiffCompression : TiffBaseDecompressor
     {
         private readonly bool isWhiteZero;