introduce .GetPixelMemory(), get rid of BufferExtensions.GetMemory()

src/ImageSharp/Advanced/AdvancedImageExtensions.cs

@@ -23,6 +23,18 @@ namespace SixLabors.ImageSharp.Advanced
             where TPixel : struct, IPixel<TPixel>
             => GetConfiguration((IConfigurable)source);
 
+        /// <summary>
+        /// Gets the <see cref="Memory{T}"/> storing the whole pixel buffer in row major order.
+        /// </summary>
+        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <param name="source">The source <see cref="ImageFrame{TPixel}"/></param>
+        /// <returns>The <see cref="Memory{T}"/></returns>
+        public static Memory<TPixel> GetPixelMemory<TPixel>(this ImageFrame<TPixel> source)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            return source.PixelBuffer.Buffer.Memory;
+        }
+
         /// <summary>
         /// Returns a reference to the 0th element of the Pixel buffer,
         /// allowing direct manipulation of pixel data through unsafe operations.

src/ImageSharp/Memory/BufferExtensions.cs

@@ -10,22 +10,6 @@ namespace SixLabors.ImageSharp.Memory
 {
     internal static class BufferExtensions
     {
-        public static Memory<T> GetMemory<T>(this IBuffer<T> buffer)
-            where T : struct
-        {
-            System.Buffers.MemoryManager<T> bufferManager = buffer as System.Buffers.MemoryManager<T>;
-
-            if (bufferManager == null)
-            {
-                // TODO: We need a better way to integrate IBuffer<T> with MemoryManager<T>. The prior should probably entirely replace the latter!
-                throw new ArgumentException(
-                    "BufferExtensions.GetMemory<T>(buffer): buffer should be convertable to System.Buffers.MemoryManager<T>!",
-                    nameof(buffer));
-            }
-
-            return bufferManager.Memory;
-        }
-
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static int Length<T>(this IBuffer<T> buffer)
             where T : struct => buffer.GetSpan().Length;

src/ImageSharp/Memory/IBuffer{T}.cs

@@ -15,9 +15,14 @@ namespace SixLabors.ImageSharp.Memory
         where T : struct
     {
         /// <summary>
-        /// Gets the span to the memory "promised" by this buffer
+        /// Gets the span to the memory "promised" by this buffer.
         /// </summary>
         /// <returns>The <see cref="Span{T}"/></returns>
         Span<T> GetSpan();
+
+        /// <summary>
+        /// Gets the <see cref="Memory{T}"/> ownerd by this buffer.
+        /// </summary>
+        Memory<T> Memory { get; }
     }
 }

src/ImageSharp/PixelAccessor{TPixel}.cs

@@ -54,8 +54,6 @@ namespace SixLabors.ImageSharp
         /// <inheritdoc />
         public Span<TPixel> Span => this.PixelBuffer.Span;
 
-        private static PixelOperations<TPixel> Operations => PixelOperations<TPixel>.Instance;
-
         /// <summary>
         /// Gets or sets the pixel at the specified position.
         /// </summary>

tests/ImageSharp.Tests/Memory/BufferTestSuite.cs

@@ -290,7 +290,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
             {
                 Span<CustomStruct> span0 = buffer.GetSpan();
                 span0[10].A = 30;
-                Memory<CustomStruct> memory = buffer.GetMemory();
+                Memory<CustomStruct> memory = buffer.Memory;
                 
                 Assert.Equal(42, memory.Length);
                 Span<CustomStruct> span1 = memory.Span;
@@ -308,7 +308,7 @@ namespace SixLabors.ImageSharp.Tests.Memory
                 Span<int> span0 = buffer.GetSpan();
                 span0[10] = 30;
 
-                Memory<int> memory = buffer.GetMemory();
+                Memory<int> memory = buffer.Memory;
 
                 using (MemoryHandle h = memory.Pin())
                 {