dropping minSizeBytes + fixing tests

src/ImageSharp/Configuration.cs

@@ -86,7 +86,7 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Gets or sets the <see cref="MemoryManager"/> that is currently in use.
         /// </summary>
-        public MemoryManager MemoryManager { get; set; } = new ArrayPoolMemoryManager(512);
+        public MemoryManager MemoryManager { get; set; } = new ArrayPoolMemoryManager();
 
         /// <summary>
         /// Gets the maximum header size of all the formats.

src/ImageSharp/Memory/ArrayPoolMemoryManager.cs

@@ -10,23 +10,20 @@ namespace SixLabors.ImageSharp.Memory
     /// </summary>
     public class ArrayPoolMemoryManager : MemoryManager
     {
-        private readonly int minSizeBytes;
+        /// <summary>
+        /// Defines the default maximum size of pooled arrays.
+        /// Currently set to a value equivalent to 16 Megapixels of an <see cref="Rgba32"/> image.
+        /// </summary>
+        public const int DefaultMaxSizeInBytes = 4096 * 4096 * 4;
+
         private readonly ArrayPool<byte> pool;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ArrayPoolMemoryManager"/> class.
-        /// By passing an integer greater than 0 as <paramref name="minSizeBytes"/>, a
-        /// minimum threshold for pooled allocations is set. Any allocation requests that
-        /// would require less size than the threshold will not be managed within the array pool.
         /// </summary>
-        /// <param name="minSizeBytes">
-        /// Minimum size, in bytes, before an array pool is used to satisfy the request.
-        /// </param>
-        public ArrayPoolMemoryManager(int minSizeBytes = 0)
+        public ArrayPoolMemoryManager()
         {
-            this.minSizeBytes = minSizeBytes;
-
-            this.pool = ArrayPool<byte>.Create(CalculateMaxArrayLength(), 50);
+            this.pool = ArrayPool<byte>.Create(DefaultMaxSizeInBytes, 50);
         }
 
         /// <inheritdoc />
@@ -41,14 +38,6 @@ namespace SixLabors.ImageSharp.Memory
             int itemSizeBytes = Unsafe.SizeOf<T>();
             int bufferSizeInBytes = itemCount * itemSizeBytes;
 
-            if (this.minSizeBytes > 0 && bufferSizeInBytes < this.minSizeBytes)
-            {
-                // Minimum size set to 8 bytes to get past a misbehaving test
-                // (otherwise PngDecoderTests.Decode_IncorrectCRCForNonCriticalChunk_ExceptionIsThrown fails for the wrong reason)
-                // TODO: Remove this once the test is fixed
-                return new Buffer<T>(new T[Math.Max(itemCount, 8)], itemCount);
-            }
-
             byte[] byteBuffer = this.pool.Rent(bufferSizeInBytes);
             var buffer = new Buffer<T>(Unsafe.As<T[]>(byteBuffer), itemCount, this);
             if (clear)
@@ -62,19 +51,8 @@ namespace SixLabors.ImageSharp.Memory
         /// <inheritdoc />
         internal override void Release<T>(Buffer<T> buffer)
         {
-            var byteBuffer = Unsafe.As<byte[]>(buffer.Array);
+            byte[] byteBuffer = Unsafe.As<byte[]>(buffer.Array);
             this.pool.Return(byteBuffer);
         }
-
-        /// <summary>
-        /// Heuristically calculates a reasonable maxArrayLength value for the backing <see cref="ArrayPool{T}"/>.
-        /// </summary>
-        /// <returns>The maxArrayLength value</returns>
-        internal static int CalculateMaxArrayLength()
-        {
-            const int MaximumExpectedImageSize = 16384 * 16384;
-            const int MaximumBytesPerPixel = 4;
-            return MaximumExpectedImageSize * MaximumBytesPerPixel;
-        }
     }
 }

src/ImageSharp/Memory/MemoryManager.cs

@@ -45,7 +45,7 @@ namespace SixLabors.ImageSharp.Memory
         internal Buffer2D<T> Allocate2D<T>(int width, int height, bool clear = false)
             where T : struct
         {
-            var buffer = this.Allocate<T>(width * height, clear);
+            Buffer<T> buffer = this.Allocate<T>(width * height, clear);
 
             return new Buffer2D<T>(buffer, width, height);
         }

tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.cs

@@ -118,8 +118,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
         }
 
         public const string DecodeBaselineJpegOutputName = "DecodeBaselineJpeg";
-
-
+        
         [Theory]
         [WithFile(TestImages.Jpeg.Baseline.Calliphora, CommonNonDefaultPixelTypes, false)]
         [WithFile(TestImages.Jpeg.Baseline.Calliphora, CommonNonDefaultPixelTypes, true)]

tests/ImageSharp.Tests/PixelFormats/PixelOperationsTests.cs

@@ -362,8 +362,9 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
 
                 if (typeof(TDest) == typeof(Vector4))
                 {
-                    Vector4[] expected = this.ExpectedDestBuffer.Array as Vector4[];
-                    Vector4[] actual = this.ActualDestBuffer.Array as Vector4[];
+                    
+                    Span<Vector4> expected = this.ExpectedDestBuffer.Span.NonPortableCast<TDest, Vector4>();
+                    Span<Vector4> actual = this.ActualDestBuffer.Span.NonPortableCast<TDest, Vector4>();
 
                     for (int i = 0; i < count; i++)
                     {