copy companding refactor from #847

Author: antonfirsov

src/ImageSharp/ColorSpaces/Companding/SRgbCompanding.cs

@@ -30,9 +30,7 @@ public static void Expand(Span<Vector4> vectors)
             for (int i = 0; i < vectors.Length; i++)
             {
                 ref Vector4 v = ref Unsafe.Add(ref baseRef, i);
-                v.X = Expand(v.X);
-                v.Y = Expand(v.Y);
-                v.Z = Expand(v.Z);
+                Expand(ref v);
             }
         }
 
@@ -48,27 +46,33 @@ public static void Compress(Span<Vector4> vectors)
             for (int i = 0; i < vectors.Length; i++)
             {
                 ref Vector4 v = ref Unsafe.Add(ref baseRef, i);
-                v.X = Compress(v.X);
-                v.Y = Compress(v.Y);
-                v.Z = Compress(v.Z);
+                Compress(ref v);
             }
         }
 
         /// <summary>
         /// Expands a companded vector to its linear equivalent with respect to the energy.
         /// </summary>
         /// <param name="vector">The vector.</param>
-        /// <returns>The <see cref="Vector4"/> representing the linear channel values.</returns>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public static Vector4 Expand(Vector4 vector) => new Vector4(Expand(vector.X), Expand(vector.Y), Expand(vector.Z), vector.W);
+        public static void Expand(ref Vector4 vector)
+        {
+            vector.X = Expand(vector.X);
+            vector.Y = Expand(vector.Y);
+            vector.Z = Expand(vector.Z);
+        }
 
         /// <summary>
         /// Compresses an uncompanded vector (linear) to its nonlinear equivalent.
         /// </summary>
         /// <param name="vector">The vector.</param>
-        /// <returns>The <see cref="Vector4"/> representing the nonlinear channel values.</returns>
         [MethodImpl(InliningOptions.ShortMethod)]
-        public static Vector4 Compress(Vector4 vector) => new Vector4(Compress(vector.X), Compress(vector.Y), Compress(vector.Z), vector.W);
+        public static void Compress(ref Vector4 vector)
+        {
+            vector.X = Compress(vector.X);
+            vector.Y = Compress(vector.Y);
+            vector.Z = Compress(vector.Z);
+        }
 
         /// <summary>
         /// Expands a companded channel to its linear equivalent with respect to the energy.

src/ImageSharp/PixelFormats/PixelConversionModifiers.cs

@@ -0,0 +1,16 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+
+namespace SixLabors.ImageSharp.PixelFormats
+{
+    [Flags]
+    internal enum PixelConversionModifiers
+    {
+        None = 0,
+        Scale = 1 << 0,
+        Premultiply = 1 << 1,
+        SRgbCompand = 1 << 2,
+    }
+}

src/ImageSharp/PixelFormats/PixelConversionModifiersExtensions.cs

@@ -0,0 +1,20 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System.Runtime.CompilerServices;
+
+namespace SixLabors.ImageSharp.PixelFormats
+{
+    internal static class PixelConversionModifiersExtensions
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static bool IsDefined(this PixelConversionModifiers modifiers, PixelConversionModifiers expected) =>
+            (modifiers & expected) == expected;
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static PixelConversionModifiers Remove(
+            this PixelConversionModifiers modifiers,
+            PixelConversionModifiers removeThis) =>
+            modifiers & ~removeThis;
+    }
+}

src/ImageSharp/PixelFormats/PixelOperations{TPixel}.cs

@@ -9,20 +9,6 @@
 
 namespace SixLabors.ImageSharp.PixelFormats
 {
-    internal enum PixelConversionModifiers
-    {
-        None = 0,
-        Scale = 1 << 0,
-        Premultiply = 1 << 1,
-        SRgbCompand = 1 << 2,
-    }
-
-    internal static class PixelConversionModifiersExtensions
-    {
-        public static bool IsDefined(this PixelConversionModifiers modifiers, PixelConversionModifiers expected) =>
-            (modifiers & expected) == expected;
-    }
-
     /// <summary>
     /// A stateless class implementing Strategy Pattern for batched pixel-data conversion operations
     /// for pixel buffers of type <typeparamref name="TPixel"/>.

tests/ImageSharp.Tests/Colorspaces/Companding/CompandingTests.cs

@@ -53,7 +53,15 @@ public void SRgbCompanding_Expand_VectorSpan(int length)
         {
             var rnd = new Random(42);
             Vector4[] source = rnd.GenerateRandomVectorArray(length, 0, 1);
-            Vector4[] expected = source.Select(v => SRgbCompanding.Expand(v)).ToArray();
+            var expected = new Vector4[source.Length];
+
+            for (int i = 0; i < source.Length; i++)
+            {
+                Vector4 s = source[i];
+                ref Vector4 e = ref expected[i];
+                SRgbCompanding.Expand(ref s);
+                e = s;
+            }
 
             SRgbCompanding.Expand(source);
 
@@ -68,7 +76,15 @@ public void SRgbCompanding_Compress_VectorSpan(int length)
         {
             var rnd = new Random(42);
             Vector4[] source = rnd.GenerateRandomVectorArray(length, 0, 1);
-            Vector4[] expected = source.Select(v => SRgbCompanding.Compress(v)).ToArray();
+            var expected = new Vector4[source.Length];
+
+            for (int i = 0; i < source.Length; i++)
+            {
+                Vector4 s = source[i];
+                ref Vector4 e = ref expected[i];
+                SRgbCompanding.Compress(ref s);
+                e = s;
+            }
 
             SRgbCompanding.Compress(source);