Use a single array pool

src/ImageSharp/Quantizers/Wu/WuArrayPool.cs

@@ -0,0 +1,36 @@
+// <copyright file="WuArrayPool.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Quantizers
+{
+    using System.Buffers;
+
+    /// <summary>
+    /// Provides array pooling for the <see cref="WuQuantizer{TColor}"/>.
+    /// This is a separate class so that the pools can be shared accross multiple generic quantizer instaces.
+    /// </summary>
+    internal static class WuArrayPool
+    {
+        /// <summary>
+        /// The long array pool.
+        /// </summary>
+        public static readonly ArrayPool<long> LongPool = ArrayPool<long>.Create(TableLength, 25);
+
+        /// <summary>
+        /// The float array pool.
+        /// </summary>
+        public static readonly ArrayPool<float> FloatPool = ArrayPool<float>.Create(TableLength, 5);
+
+        /// <summary>
+        /// The byte array pool.
+        /// </summary>
+        public static readonly ArrayPool<byte> BytePool = ArrayPool<byte>.Create(TableLength, 5);
+
+        /// <summary>
+        /// The table length. Matches the calculated value in <see cref="WuQuantizer{TColor}"/>
+        /// </summary>
+        private const int TableLength = 2471625;
+    }
+}

src/ImageSharp/Quantizers/Wu/WuQuantizer.cs

@@ -58,21 +58,6 @@ namespace ImageSharp.Quantizers
         /// </summary>
         private const int TableLength = IndexCount * IndexCount * IndexCount * IndexAlphaCount;
 
-        /// <summary>
-        /// The long array pool.
-        /// </summary>
-        private static readonly ArrayPool<long> LongPool = ArrayPool<long>.Create(TableLength, 25);
-
-        /// <summary>
-        /// The float array pool.
-        /// </summary>
-        private static readonly ArrayPool<float> FloatPool = ArrayPool<float>.Create(TableLength, 5);
-
-        /// <summary>
-        /// The byte array pool.
-        /// </summary>
-        private static readonly ArrayPool<byte> BytePool = ArrayPool<byte>.Create(TableLength, 5);
-
         /// <summary>
         /// Moment of <c>P(c)</c>.
         /// </summary>
@@ -118,13 +103,13 @@ namespace ImageSharp.Quantizers
         /// </summary>
         public WuQuantizer()
         {
-            this.vwt = LongPool.Rent(TableLength);
-            this.vmr = LongPool.Rent(TableLength);
-            this.vmg = LongPool.Rent(TableLength);
-            this.vmb = LongPool.Rent(TableLength);
-            this.vma = LongPool.Rent(TableLength);
-            this.m2 = FloatPool.Rent(TableLength);
-            this.tag = BytePool.Rent(TableLength);
+            this.vwt = WuArrayPool.LongPool.Rent(TableLength);
+            this.vmr = WuArrayPool.LongPool.Rent(TableLength);
+            this.vmg = WuArrayPool.LongPool.Rent(TableLength);
+            this.vmb = WuArrayPool.LongPool.Rent(TableLength);
+            this.vma = WuArrayPool.LongPool.Rent(TableLength);
+            this.m2 = WuArrayPool.FloatPool.Rent(TableLength);
+            this.tag = WuArrayPool.BytePool.Rent(TableLength);
         }
 
         /// <inheritdoc/>
@@ -789,13 +774,13 @@ namespace ImageSharp.Quantizers
                 });
 
             // Cleanup
-            LongPool.Return(this.vwt);
-            LongPool.Return(this.vmr);
-            LongPool.Return(this.vmg);
-            LongPool.Return(this.vmb);
-            LongPool.Return(this.vma);
-            FloatPool.Return(this.m2);
-            BytePool.Return(this.tag);
+            WuArrayPool.LongPool.Return(this.vwt);
+            WuArrayPool.LongPool.Return(this.vmr);
+            WuArrayPool.LongPool.Return(this.vmg);
+            WuArrayPool.LongPool.Return(this.vmb);
+            WuArrayPool.LongPool.Return(this.vma);
+            WuArrayPool.FloatPool.Return(this.m2);
+            WuArrayPool.BytePool.Return(this.tag);
 
             return new QuantizedImage<TColor>(width, height, pallette, pixels);
         }