Update PixelBlender{TPixel}.cs

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

@@ -1,10 +1,10 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using SixLabors.ImageSharp.Memory;
 using System;
 using System.Buffers;
 using System.Numerics;
-using SixLabors.ImageSharp.Memory;
 
 namespace SixLabors.ImageSharp.PixelFormats
 {
@@ -27,25 +27,6 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <returns>The final pixel value after composition.</returns>
         public abstract TPixel Blend(TPixel background, TPixel source, float amount);
 
-        /// <summary>
-        /// Blends 2 rows together
-        /// </summary>
-        /// <param name="configuration"><see cref="Configuration"/> to use internally</param>
-        /// <param name="destination">the destination span</param>
-        /// <param name="background">the background span</param>
-        /// <param name="source">the source span</param>
-        /// <param name="amount">
-        /// A span with values between 0 and 1 indicating the weight of the second source vector.
-        /// At amount = 0, "background" is returned, at amount = 1, "source" is returned.
-        /// </param>
-        public void Blend(
-            Configuration configuration,
-            Span<TPixel> destination,
-            ReadOnlySpan<TPixel> background,
-            ReadOnlySpan<TPixel> source,
-            ReadOnlySpan<float> amount)
-            => this.Blend<TPixel>(configuration, destination, background, source, amount);
-
         /// <summary>
         /// Blends 2 rows together
         /// </summary>
@@ -55,7 +36,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <param name="background">the background span</param>
         /// <param name="source">the source span</param>
         /// <param name="amount">
-        /// A span with values between 0 and 1 indicating the weight of the second source vector.
+        /// A value between 0 and 1 indicating the weight of the second source vector.
         /// At amount = 0, "background" is returned, at amount = 1, "source" is returned.
         /// </param>
         public void Blend<TPixelSrc>(
@@ -63,12 +44,12 @@ namespace SixLabors.ImageSharp.PixelFormats
             Span<TPixel> destination,
             ReadOnlySpan<TPixel> background,
             ReadOnlySpan<TPixelSrc> source,
-            ReadOnlySpan<float> amount)
+            float amount)
             where TPixelSrc : struct, IPixel<TPixelSrc>
         {
             Guard.MustBeGreaterThanOrEqualTo(background.Length, destination.Length, nameof(background.Length));
             Guard.MustBeGreaterThanOrEqualTo(source.Length, destination.Length, nameof(source.Length));
-            Guard.MustBeGreaterThanOrEqualTo(amount.Length, destination.Length, nameof(amount.Length));
+            Guard.MustBeBetweenOrEqualTo(amount, 0, 1, nameof(amount));
 
             using (IMemoryOwner<Vector4> buffer =
                 configuration.MemoryAllocator.Allocate<Vector4>(destination.Length * 3))
@@ -89,6 +70,25 @@ namespace SixLabors.ImageSharp.PixelFormats
             }
         }
 
+        /// <summary>
+        /// Blends 2 rows together
+        /// </summary>
+        /// <param name="configuration"><see cref="Configuration"/> to use internally</param>
+        /// <param name="destination">the destination span</param>
+        /// <param name="background">the background span</param>
+        /// <param name="source">the source span</param>
+        /// <param name="amount">
+        /// A span with values between 0 and 1 indicating the weight of the second source vector.
+        /// At amount = 0, "background" is returned, at amount = 1, "source" is returned.
+        /// </param>
+        public void Blend(
+            Configuration configuration,
+            Span<TPixel> destination,
+            ReadOnlySpan<TPixel> background,
+            ReadOnlySpan<TPixel> source,
+            ReadOnlySpan<float> amount)
+            => this.Blend<TPixel>(configuration, destination, background, source, amount);
+
         /// <summary>
         /// Blends 2 rows together
         /// </summary>
@@ -98,7 +98,7 @@ namespace SixLabors.ImageSharp.PixelFormats
         /// <param name="background">the background span</param>
         /// <param name="source">the source span</param>
         /// <param name="amount">
-        /// A value between 0 and 1 indicating the weight of the second source vector.
+        /// A span with values between 0 and 1 indicating the weight of the second source vector.
         /// At amount = 0, "background" is returned, at amount = 1, "source" is returned.
         /// </param>
         public void Blend<TPixelSrc>(
@@ -106,12 +106,12 @@ namespace SixLabors.ImageSharp.PixelFormats
             Span<TPixel> destination,
             ReadOnlySpan<TPixel> background,
             ReadOnlySpan<TPixelSrc> source,
-            float amount)
+            ReadOnlySpan<float> amount)
             where TPixelSrc : struct, IPixel<TPixelSrc>
         {
             Guard.MustBeGreaterThanOrEqualTo(background.Length, destination.Length, nameof(background.Length));
             Guard.MustBeGreaterThanOrEqualTo(source.Length, destination.Length, nameof(source.Length));
-            Guard.MustBeBetweenOrEqualTo(amount, 0, 1, nameof(amount));
+            Guard.MustBeGreaterThanOrEqualTo(amount.Length, destination.Length, nameof(amount.Length));
 
             using (IMemoryOwner<Vector4> buffer =
                 configuration.MemoryAllocator.Allocate<Vector4>(destination.Length * 3))