Added new class that can be used to store a row of pixels.

src/ImageSharp/Image/PixelRow.cs

@@ -0,0 +1,85 @@
+// <copyright file="PixelRow.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp
+{
+    using System;
+    using System.IO;
+    using System.Runtime.InteropServices;
+
+    public unsafe sealed class PixelRow<TColor, TPacked> : IDisposable
+        where TColor : struct, IPackedPixel<TPacked>
+        where TPacked : struct
+    {
+        private readonly GCHandle handle;
+
+        public PixelRow(int width, ComponentOrder componentOrder)
+          : this(width, componentOrder, 0)
+        {
+        }
+
+        public PixelRow(int width, ComponentOrder componentOrder, int padding)
+        {
+            this.Width = width;
+            this.ComponentOrder = componentOrder;
+            this.Data = new byte[(width * GetComponentCount(componentOrder)) + padding];
+            this.handle = GCHandle.Alloc(this.Data, GCHandleType.Pinned);
+            this.DataPointer = (byte*)this.handle.AddrOfPinnedObject().ToPointer();
+        }
+
+        ~PixelRow()
+        {
+            this.Dispose();
+        }
+
+        public byte[] Data { get; }
+
+        public byte* DataPointer { get; private set; }
+
+        public ComponentOrder ComponentOrder { get; }
+
+        public int Width { get; }
+
+        public void Read(Stream stream)
+        {
+            stream.Read(this.Data, 0, this.Data.Length);
+        }
+
+        public void Write(Stream stream)
+        {
+            stream.Write(this.Data, 0, this.Data.Length);
+        }
+
+        public void Dispose()
+        {
+          if (this.DataPointer == null)
+          {
+              return;
+          }
+
+          if (this.handle.IsAllocated)
+          {
+              this.handle.Free();
+          }
+
+          this.DataPointer = null;
+        }
+
+        private static int GetComponentCount(ComponentOrder componentOrder)
+        {
+          switch (componentOrder)
+          {
+            case ComponentOrder.BGR:
+            case ComponentOrder.RGB:
+              return 3;
+            case ComponentOrder.BGRA:
+            case ComponentOrder.RGBA:
+              return 4;
+          }
+
+          throw new NotSupportedException();
+        }
+    }
+}