Introduce extended pixel conversion

ImageSharp.sln.DotSettings

@@ -382,6 +382,7 @@
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpKeepExistingMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpPlaceEmbeddedOnSameLineMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpRenamePlacementToArrangementMigration/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpUseContinuousIndentInsideBracesMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EAddAccessorOwnerDeclarationBracesMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EAlwaysTreatStructAsNotReorderableMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002ECSharpPlaceAttributeOnSameLineMigration/@EntryIndexedValue">True</s:Boolean>

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/Common/Helpers/Guard.cs

@@ -257,6 +257,26 @@ public static void DestinationShouldNotBeTooShort<TSource, TDest>(
             }
         }
 
+        /// <summary>
+        /// Verifies that the 'destination' span is not shorter than 'source'.
+        /// </summary>
+        /// <typeparam name="TSource">The source element type</typeparam>
+        /// <typeparam name="TDest">The destination element type</typeparam>
+        /// <param name="source">The source span</param>
+        /// <param name="destination">The destination span</param>
+        /// <param name="destinationParamName">The name of the argument for 'destination'</param>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public static void DestinationShouldNotBeTooShort<TSource, TDest>(
+            Span<TSource> source,
+            Span<TDest> destination,
+            string destinationParamName)
+        {
+            if (destination.Length < source.Length)
+            {
+                ThrowArgumentException($"Destination span is too short!", destinationParamName);
+            }
+        }
+
         /// <summary>
         /// Verifies, that the `source` span has the length of 'minLength', or longer.
         /// </summary>

src/ImageSharp/Formats/Jpeg/Components/Decoder/JpegImagePostProcessor.cs

@@ -173,7 +173,7 @@ private void ConvertColorsInto<TPixel>(ImageFrame<TPixel> destination)
                 Span<TPixel> destRow = destination.GetPixelRowSpan(yy);
 
                 // TODO: Investigate if slicing is actually necessary
-                PixelOperations<TPixel>.Instance.FromVector4(this.configuration, this.rgbaBuffer.GetSpan().Slice(0, destRow.Length), destRow);
+                PixelOperations<TPixel>.Instance.FromVector4Destructive(this.configuration, this.rgbaBuffer.GetSpan().Slice(0, destRow.Length), destRow);
             }
         }
     }

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

@@ -112,21 +112,15 @@ public void Blend<TPixelSrc>(
                 Span<Vector4> backgroundSpan = buffer.Slice(destination.Length, destination.Length);
                 Span<Vector4> sourceSpan = buffer.Slice(destination.Length * 2, destination.Length);
 
-                PixelOperations<TPixel>.Instance.ToScaledVector4(
-                    configuration,
-                    background.Slice(0, background.Length),
-                    backgroundSpan);
-                PixelOperations<TPixelSrc>.Instance.ToScaledVector4(
-                    configuration,
-                    source.Slice(0, background.Length),
-                    sourceSpan);
+                ReadOnlySpan<TPixel> sourcePixels = background.Slice(0, background.Length);
+                PixelOperations<TPixel>.Instance.ToVector4(configuration, sourcePixels, backgroundSpan, PixelConversionModifiers.Scale);
+                ReadOnlySpan<TPixelSrc> sourcePixels1 = source.Slice(0, background.Length);
+                PixelOperations<TPixelSrc>.Instance.ToVector4(configuration, sourcePixels1, sourceSpan, PixelConversionModifiers.Scale);
 
                 this.BlendFunction(destinationSpan, backgroundSpan, sourceSpan, amount);
 
-                PixelOperations<TPixel>.Instance.FromScaledVector4(
-                    configuration,
-                    destinationSpan.Slice(0, background.Length),
-                    destination);
+                Span<Vector4> sourceVectors = destinationSpan.Slice(0, background.Length);
+                PixelOperations<TPixel>.Instance.FromVector4Destructive(configuration, sourceVectors, destination, PixelConversionModifiers.Scale);
             }
         }
 
@@ -161,21 +155,15 @@ public void Blend<TPixelSrc>(
                 Span<Vector4> backgroundSpan = buffer.Slice(destination.Length, destination.Length);
                 Span<Vector4> sourceSpan = buffer.Slice(destination.Length * 2, destination.Length);
 
-                PixelOperations<TPixel>.Instance.ToScaledVector4(
-                    configuration,
-                    background.Slice(0, background.Length),
-                    backgroundSpan);
-                PixelOperations<TPixelSrc>.Instance.ToScaledVector4(
-                    configuration,
-                    source.Slice(0, background.Length),
-                    sourceSpan);
+                ReadOnlySpan<TPixel> sourcePixels = background.Slice(0, background.Length);
+                PixelOperations<TPixel>.Instance.ToVector4(configuration, sourcePixels, backgroundSpan, PixelConversionModifiers.Scale);
+                ReadOnlySpan<TPixelSrc> sourcePixels1 = source.Slice(0, background.Length);
+                PixelOperations<TPixelSrc>.Instance.ToVector4(configuration, sourcePixels1, sourceSpan, PixelConversionModifiers.Scale);
 
                 this.BlendFunction(destinationSpan, backgroundSpan, sourceSpan, amount);
 
-                PixelOperations<TPixel>.Instance.FromScaledVector4(
-                    configuration,
-                    destinationSpan.Slice(0, background.Length),
-                    destination);
+                Span<Vector4> sourceVectors = destinationSpan.Slice(0, background.Length);
+                PixelOperations<TPixel>.Instance.FromVector4Destructive(configuration, sourceVectors, destination, PixelConversionModifiers.Scale);
             }
         }
     }

src/ImageSharp/PixelFormats/PixelConversionModifiers.cs

@@ -0,0 +1,40 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+
+using SixLabors.ImageSharp.ColorSpaces.Companding;
+
+namespace SixLabors.ImageSharp.PixelFormats
+{
+    /// <summary>
+    /// Flags responsible to select additional operations which could be effitiently applied in
+    /// <see cref="PixelOperations{TPixel}.ToVector4(SixLabors.ImageSharp.Configuration,System.ReadOnlySpan{TPixel},System.Span{System.Numerics.Vector4},SixLabors.ImageSharp.PixelFormats.PixelConversionModifiers)"/>
+    /// or
+    /// <see cref="PixelOperations{TPixel}.FromVector4Destructive(SixLabors.ImageSharp.Configuration,System.Span{System.Numerics.Vector4},System.Span{TPixel},SixLabors.ImageSharp.PixelFormats.PixelConversionModifiers)"/>
+    /// knowing the pixel type.
+    /// </summary>
+    [Flags]
+    internal enum PixelConversionModifiers
+    {
+        /// <summary>
+        /// No special operation is selected
+        /// </summary>
+        None = 0,
+
+        /// <summary>
+        /// Select <see cref="IPixel.ToScaledVector4"/> and <see cref="IPixel.FromScaledVector4"/> instead the standard (non scaled) variants.
+        /// </summary>
+        Scale = 1 << 0,
+
+        /// <summary>
+        /// Enable alpha premultiplication / unpremultiplication
+        /// </summary>
+        Premultiply = 1 << 1,
+
+        /// <summary>
+        /// Enable SRGB companding (defined in <see cref="SRgbCompanding"/>).
+        /// </summary>
+        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/PixelImplementations/Generated/Argb32.PixelOperations.Generated.cs

@@ -42,29 +42,16 @@ internal override void ToArgb32(Configuration configuration, ReadOnlySpan<Argb32
             }
 
             /// <inheritdoc />
-            internal override void FromVector4(Configuration configuration, ReadOnlySpan<Vector4> sourceVectors, Span<Argb32> destPixels)
+            internal override void FromVector4Destructive(Configuration configuration, Span<Vector4> sourceVectors, Span<Argb32> destPixels, PixelConversionModifiers modifiers)
             {
-                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, false);
+                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, modifiers.Remove(PixelConversionModifiers.Scale));
             }
 
             /// <inheritdoc />
-            internal override void ToVector4(Configuration configuration, ReadOnlySpan<Argb32> sourcePixels, Span<Vector4> destVectors)
+            internal override void ToVector4(Configuration configuration, ReadOnlySpan<Argb32> sourcePixels, Span<Vector4> destVectors, PixelConversionModifiers modifiers)
             {
-                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, false);
+                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, modifiers.Remove(PixelConversionModifiers.Scale));
             }
-
-            /// <inheritdoc />
-            internal override void FromScaledVector4(Configuration configuration, ReadOnlySpan<Vector4> sourceVectors, Span<Argb32> destPixels)
-            {
-                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, true);
-            }
-
-            /// <inheritdoc />
-            internal override void ToScaledVector4(Configuration configuration, ReadOnlySpan<Argb32> sourcePixels, Span<Vector4> destVectors)
-            {
-                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, true);
-            }
-
             /// <inheritdoc />
             internal override void ToRgba32(Configuration configuration, ReadOnlySpan<Argb32> sourcePixels, Span<Rgba32> destPixels)
             {

src/ImageSharp/PixelFormats/PixelImplementations/Generated/Bgr24.PixelOperations.Generated.cs

@@ -42,30 +42,17 @@ internal override void ToBgr24(Configuration configuration, ReadOnlySpan<Bgr24>
             }
 
             /// <inheritdoc />
-            internal override void FromVector4(Configuration configuration, ReadOnlySpan<Vector4> sourceVectors, Span<Bgr24> destPixels)
+            internal override void FromVector4Destructive(Configuration configuration, Span<Vector4> sourceVectors, Span<Bgr24> destPixels, PixelConversionModifiers modifiers)
             {
-                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, false);
+                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, modifiers.Remove(PixelConversionModifiers.Scale | PixelConversionModifiers.Premultiply));
             }
 
             /// <inheritdoc />
-            internal override void ToVector4(Configuration configuration, ReadOnlySpan<Bgr24> sourcePixels, Span<Vector4> destVectors)
+            internal override void ToVector4(Configuration configuration, ReadOnlySpan<Bgr24> sourcePixels, Span<Vector4> destVectors, PixelConversionModifiers modifiers)
             {
-                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, false);
+                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, modifiers.Remove(PixelConversionModifiers.Scale | PixelConversionModifiers.Premultiply));
             }
 
-            /// <inheritdoc />
-            internal override void FromScaledVector4(Configuration configuration, ReadOnlySpan<Vector4> sourceVectors, Span<Bgr24> destPixels)
-            {
-                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, true);
-            }
-
-            /// <inheritdoc />
-            internal override void ToScaledVector4(Configuration configuration, ReadOnlySpan<Bgr24> sourcePixels, Span<Vector4> destVectors)
-            {
-                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, true);
-            }
-
-
             /// <inheritdoc />
             internal override void ToArgb32(Configuration configuration, ReadOnlySpan<Bgr24> sourcePixels, Span<Argb32> destPixels)
             {

src/ImageSharp/PixelFormats/PixelImplementations/Generated/Bgra32.PixelOperations.Generated.cs

@@ -42,29 +42,16 @@ internal override void ToBgra32(Configuration configuration, ReadOnlySpan<Bgra32
             }
 
             /// <inheritdoc />
-            internal override void FromVector4(Configuration configuration, ReadOnlySpan<Vector4> sourceVectors, Span<Bgra32> destPixels)
+            internal override void FromVector4Destructive(Configuration configuration, Span<Vector4> sourceVectors, Span<Bgra32> destPixels, PixelConversionModifiers modifiers)
             {
-                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, false);
+                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, modifiers.Remove(PixelConversionModifiers.Scale));
             }
 
             /// <inheritdoc />
-            internal override void ToVector4(Configuration configuration, ReadOnlySpan<Bgra32> sourcePixels, Span<Vector4> destVectors)
+            internal override void ToVector4(Configuration configuration, ReadOnlySpan<Bgra32> sourcePixels, Span<Vector4> destVectors, PixelConversionModifiers modifiers)
             {
-                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, false);
+                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, modifiers.Remove(PixelConversionModifiers.Scale));
             }
-
-            /// <inheritdoc />
-            internal override void FromScaledVector4(Configuration configuration, ReadOnlySpan<Vector4> sourceVectors, Span<Bgra32> destPixels)
-            {
-                Vector4Converters.RgbaCompatible.FromVector4(configuration, this, sourceVectors, destPixels, true);
-            }
-
-            /// <inheritdoc />
-            internal override void ToScaledVector4(Configuration configuration, ReadOnlySpan<Bgra32> sourcePixels, Span<Vector4> destVectors)
-            {
-                Vector4Converters.RgbaCompatible.ToVector4(configuration, this, sourcePixels, destVectors, true);
-            }
-
             /// <inheritdoc />
             internal override void ToRgba32(Configuration configuration, ReadOnlySpan<Bgra32> sourcePixels, Span<Rgba32> destPixels)
             {