do not use Configuration.Default.MemoryManager in AddFrame()

src/ImageSharp/Image/ImageFrame.LoadPixelData.cs

@@ -20,30 +20,32 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the given byte array in <typeparamref name="TPixel"/> format.
         /// </summary>
+        /// <param name="memoryManager">The memory manager to use for allocations</param>
         /// <param name="data">The byte array containing image data.</param>
         /// <param name="width">The width of the final image.</param>
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        public static ImageFrame<TPixel> LoadPixelData<TPixel>(Span<byte> data, int width, int height)
+        public static ImageFrame<TPixel> LoadPixelData<TPixel>(MemoryManager memoryManager, Span<byte> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
-            => LoadPixelData(data.NonPortableCast<byte, TPixel>(), width, height);
+            => LoadPixelData(memoryManager, data.NonPortableCast<byte, TPixel>(), width, height);
 
         /// <summary>
         /// Create a new instance of the <see cref="Image{TPixel}"/> class from the raw <typeparamref name="TPixel"/> data.
         /// </summary>
+        /// <param name="memoryManager">The memory manager to use for allocations</param>
         /// <param name="data">The Span containing the image Pixel data.</param>
         /// <param name="width">The width of the final image.</param>
         /// <param name="height">The height of the final image.</param>
         /// <typeparam name="TPixel">The pixel format.</typeparam>
         /// <returns>A new <see cref="Image{TPixel}"/>.</returns>
-        public static ImageFrame<TPixel> LoadPixelData<TPixel>(Span<TPixel> data, int width, int height)
+        public static ImageFrame<TPixel> LoadPixelData<TPixel>(MemoryManager memoryManager, Span<TPixel> data, int width, int height)
             where TPixel : struct, IPixel<TPixel>
         {
             int count = width * height;
             Guard.MustBeGreaterThanOrEqualTo(data.Length, count, nameof(data));
 
-            var image = new ImageFrame<TPixel>(Configuration.Default.MemoryManager, width, height);
+            var image = new ImageFrame<TPixel>(memoryManager, width, height);
             SpanHelper.Copy(data, image.GetPixelSpan(), count);
 
             return image;

src/ImageSharp/Image/ImageFrameCollection.cs

@@ -80,7 +80,11 @@ namespace SixLabors.ImageSharp
         /// <inheritdoc/>
         public ImageFrame<TPixel> AddFrame(TPixel[] data)
         {
-            var frame = ImageFrame.LoadPixelData(new Span<TPixel>(data), this.RootFrame.Width, this.RootFrame.Height);
+            var frame = ImageFrame.LoadPixelData(
+                this.parent.GetMemoryManager(),
+                new Span<TPixel>(data),
+                this.RootFrame.Width,
+                this.RootFrame.Height);
             this.frames.Add(frame);
             return frame;
         }

src/ImageSharp/Memory/Buffer2D{T}.cs

@@ -34,8 +34,14 @@ namespace SixLabors.ImageSharp.Memory
         /// <inheritdoc />
         public int Height { get; private set; }
 
+        /// <summary>
+        /// Gets the span to the whole area.
+        /// </summary>
         public Span<T> Span => this.Buffer.Span;
 
+        /// <summary>
+        /// Gets the backing <see cref="IBuffer{T}"/>
+        /// </summary>
         public IBuffer<T> Buffer { get; private set; }
 
         /// <summary>
@@ -56,11 +62,20 @@ namespace SixLabors.ImageSharp.Memory
             }
         }
 
+        /// <summary>
+        /// Disposes the <see cref="Buffer2D{T}"/> instance
+        /// </summary>
         public void Dispose()
         {
             this.Buffer?.Dispose();
         }
 
+        /// <summary>
+        /// Swap the contents (<see cref="Buffer"/>, <see cref="Width"/>, <see cref="Height"/>) of the two buffers.
+        /// Useful to transfer the contents of a temporal <see cref="Buffer2D{T}"/> to a persistent <see cref="ImageFrame{TPixel}.PixelBuffer"/>
+        /// </summary>
+        /// <param name="a">The first buffer</param>
+        /// <param name="b">The second buffer</param>
         public static void SwapContents(Buffer2D<T> a, Buffer2D<T> b)
         {
             Size aSize = a.Size();