Merge pull request #1750 from SixLabors/bp/tiffjpegcompression

Revert unoptimized edits to Jpeg Encoder.

Author: JimBobSquarePants

src/ImageSharp/Formats/Jpeg/Components/Block8x8F.cs

@@ -104,15 +104,15 @@ public float this[int idx]
             {
                 GuardBlockIndex(idx);
                 ref float selfRef = ref Unsafe.As<Block8x8F, float>(ref this);
-                return Unsafe.Add(ref selfRef, idx);
+                return Unsafe.Add(ref selfRef, (nint)(uint)idx);
             }
 
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
             set
             {
                 GuardBlockIndex(idx);
                 ref float selfRef = ref Unsafe.As<Block8x8F, float>(ref this);
-                Unsafe.Add(ref selfRef, idx) = value;
+                Unsafe.Add(ref selfRef, (nint)(uint)idx) = value;
             }
         }
 

src/ImageSharp/Formats/Jpeg/Components/Encoder/RgbForwardConverter{TPixel}.cs

@@ -103,7 +103,7 @@ private static void CopyToBlock(Span<Rgb24> rgbSpan, ref Block8x8F redBlock, ref
 
             for (int i = 0; i < Block8x8F.Size; i++)
             {
-                Rgb24 c = Unsafe.Add(ref rgbStart, i);
+                Rgb24 c = Unsafe.Add(ref rgbStart, (nint)(uint)i);
 
                 redBlock[i] = c.R;
                 greenBlock[i] = c.G;

src/ImageSharp/Formats/Jpeg/JpegEncoderCore.cs

@@ -567,14 +567,14 @@ private void WriteStartOfFrame(int width, int height, int componentCount, ReadOn
             // This uses a C#'s compiler optimization that refers to the static data segment of the assembly,
             // and doesn't incur any allocation at all.
             // "default" to 4:2:0
-            ReadOnlySpan<byte> subsamples = stackalloc byte[]
+            ReadOnlySpan<byte> subsamples = new byte[]
             {
                 0x22,
                 0x11,
                 0x11
             };
 
-            ReadOnlySpan<byte> chroma = stackalloc byte[]
+            ReadOnlySpan<byte> chroma = new byte[]
             {
                 0x00,
                 0x01,
@@ -583,7 +583,7 @@ private void WriteStartOfFrame(int width, int height, int componentCount, ReadOn
 
             if (this.colorType == JpegColorType.Luminance)
             {
-                subsamples = stackalloc byte[]
+                subsamples = new byte[]
                 {
                     0x11,
                     0x00,
@@ -596,7 +596,7 @@ private void WriteStartOfFrame(int width, int height, int componentCount, ReadOn
                 {
                     case JpegColorType.YCbCrRatio444:
                     case JpegColorType.Rgb:
-                        subsamples = stackalloc byte[]
+                        subsamples = new byte[]
                         {
                             0x11,
                             0x11,
@@ -605,7 +605,7 @@ private void WriteStartOfFrame(int width, int height, int componentCount, ReadOn
 
                         if (this.colorType == JpegColorType.Rgb)
                         {
-                            chroma = stackalloc byte[]
+                            chroma = new byte[]
                             {
                                 0x00,
                                 0x00,
@@ -615,7 +615,7 @@ private void WriteStartOfFrame(int width, int height, int componentCount, ReadOn
 
                         break;
                     case JpegColorType.YCbCrRatio420:
-                        subsamples = stackalloc byte[]
+                        subsamples = new byte[]
                         {
                             0x22,
                             0x11,
@@ -658,7 +658,7 @@ private void WriteStartOfScan(int componentCount, ReadOnlySpan<byte> componentId
         {
             // This uses a C#'s compiler optimization that refers to the static data segment of the assembly,
             // and doesn't incur any allocation at all.
-            ReadOnlySpan<byte> huffmanId = stackalloc byte[]
+            ReadOnlySpan<byte> huffmanId = new byte[]
             {
                 0x00,
                 0x11,
@@ -668,7 +668,7 @@ private void WriteStartOfScan(int componentCount, ReadOnlySpan<byte> componentId
             // Use the same DC/AC tables for all channels for RGB.
             if (this.colorType == JpegColorType.Rgb)
             {
-                huffmanId = stackalloc byte[]
+                huffmanId = new byte[]
                 {
                     0x00,
                     0x00,