Changes ISpriteSource.Frames to be of type IReadOnlyList<ISpriteFrame>.

- Updated implementations to return a ReadOnlyList around an array (to reduce wasted memory from exposing lists or lazy enumerators around lists).
- Protect non-public ISpriteFrame classes by making them inner classes to prevent casting.
- Added an AsReadOnly extension method for lists.

OpenRA.Editor/RenderUtils.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -101,7 +101,7 @@ namespace OpenRA.Editor
 				}
 
 				bitmap.UnlockBits(data);
-				return new ResourceTemplate { Bitmap = bitmap, Info = info, Value = shp.Frames.Count() - 1 };
+				return new ResourceTemplate { Bitmap = bitmap, Info = info, Value = shp.Frames.Count - 1 };
 			}
 		}
 	}

OpenRA.Editor/TileSetRenderer.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -20,9 +20,9 @@ namespace OpenRA.Editor
 {
 	public class TileSetRenderer
 	{
+		public readonly int TileSize;
 		public TileSet TileSet;
 		Dictionary<ushort, List<byte[]>> templates;
-		public readonly int TileSize;
 
 		// Extract a square tile that the editor can render
 		byte[] ExtractSquareTile(ISpriteFrame frame)
@@ -61,7 +61,7 @@ namespace OpenRA.Editor
 			if (frames != null)
 			{
 				var ret = new List<byte[]>();
-				var srcFrames = source.Frames.ToArray();
+				var srcFrames = source.Frames;
 				foreach (var i in frames)
 					ret.Add(ExtractSquareTile(srcFrames[i]));
 

OpenRA.Game/FileFormats/R8Reader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made 
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -14,6 +14,8 @@ using System.IO;
 using OpenRA.Graphics;
 
 namespace OpenRA.FileFormats
+{
+	public class R8Reader : ISpriteSource
 	{
 		class R8Image : ISpriteFrame
 		{
@@ -37,7 +39,8 @@ namespace OpenRA.FileFormats
 				Size = new Size(width, height);
 				Offset = new int2(width / 2 - x, height / 2 - y);
 
-			/*var imageOffset = */s.ReadInt32();
+				/*var imageOffset = */
+				s.ReadInt32();
 				var paletteOffset = s.ReadInt32();
 				var bpp = s.ReadUInt8();
 				if (bpp != 8)
@@ -58,20 +61,20 @@ namespace OpenRA.FileFormats
 			}
 		}
 
-	public class R8Reader : ISpriteSource
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-	{
-		readonly List<ISpriteFrame> frames = new List<ISpriteFrame>();
-		public IEnumerable<ISpriteFrame> Frames { get { return frames; } }
 		public bool CacheWhenLoadingTileset { get { return true; } }
 
 		public readonly int ImageCount;
 		public R8Reader(Stream stream)
 		{
+			var frames = new List<R8Image>();
 			while (stream.Position < stream.Length)
 			{
 				frames.Add(new R8Image(stream));
 				ImageCount++;
 			}
+
+			Frames = frames.ToArray().AsReadOnly();
 		}
 	}
 }

OpenRA.Game/FileFormats/ShpD2Reader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -9,12 +9,13 @@
 #endregion
 
 using System;
-using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
 using OpenRA.Graphics;
 
 namespace OpenRA.FileFormats
+{
+	public class ShpD2Reader : ISpriteSource
 	{
 		[Flags] enum FormatFlags : int
 		{
@@ -82,10 +83,7 @@ namespace OpenRA.FileFormats
 			}
 		}
 
-	public class ShpD2Reader : ISpriteSource
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-	{
-		readonly List<ISpriteFrame> frames = new List<ISpriteFrame>();
-		public IEnumerable<ISpriteFrame> Frames { get { return frames; } }
 		public bool CacheWhenLoadingTileset { get { return false; } }
 
 		public ShpD2Reader(Stream s)
@@ -103,10 +101,12 @@ namespace OpenRA.FileFormats
 			for (var i = 0; i < imageCount + 1; i++)
 				offsets[i] = (twoByteOffset ? s.ReadUInt16() : s.ReadUInt32()) + 2;
 
-			for (var i = 0; i < imageCount; i++)
+			var frames = new Frame[imageCount];
+			Frames = frames.AsReadOnly();
+			for (var i = 0; i < frames.Length; i++)
 			{
 				s.Position = offsets[i];
-				frames.Add(new Frame(s));
+				frames[i] = new Frame(s);
 			}
 		}
 	}

OpenRA.Game/FileFormats/ShpReader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -16,6 +16,8 @@ using System.Linq;
 using OpenRA.Graphics;
 
 namespace OpenRA.FileFormats
+{
+	public class ShpReader : ISpriteSource
 	{
 		enum Format { Format20 = 0x20, Format40 = 0x40, Format80 = 0x80 }
 
@@ -34,6 +36,7 @@ namespace OpenRA.FileFormats
 			public ImageHeader RefImage;
 
 			ShpReader reader;
+
 			// Used by ShpWriter
 			public ImageHeader() { }
 
@@ -56,11 +59,7 @@ namespace OpenRA.FileFormats
 			}
 		}
 
-	public class ShpReader : ISpriteSource
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-	{
-		readonly List<ImageHeader> headers = new List<ImageHeader>();
-		Lazy<IEnumerable<ISpriteFrame>> spriteFrames;
-		public IEnumerable<ISpriteFrame> Frames { get { return spriteFrames.Value; } }
 		public bool CacheWhenLoadingTileset { get { return false; } }
 		public readonly Size Size;
 
@@ -79,8 +78,10 @@ namespace OpenRA.FileFormats
 			Size = new Size(width, height);
 
 			stream.Position += 4;
-			for (var i = 0; i < imageCount; i++)
+			var headers = new ImageHeader[imageCount];
-				headers.Add(new ImageHeader(stream, this));
+			Frames = headers.AsReadOnly();
+			for (var i = 0; i < headers.Length; i++)
+				headers[i] = new ImageHeader(stream, this);
 
 			// Skip eof and zero headers
 			stream.Position += 16;
@@ -91,7 +92,6 @@ namespace OpenRA.FileFormats
 				var h = headers[i];
 				if (h.Format == Format.Format20)
 					h.RefImage = headers[i - 1];
-
 				else if (h.Format == Format.Format40 && !offsets.TryGetValue(h.RefOffset, out h.RefImage))
 					throw new InvalidDataException("Reference doesnt point to image data {0}->{1}".F(h.FileOffset, h.RefOffset));
 			}
@@ -101,8 +101,6 @@ namespace OpenRA.FileFormats
 
 			foreach (var h in headers)
 				Decompress(h);
-
-			spriteFrames = Exts.Lazy(() => headers.Cast<ISpriteFrame>());
 		}
 
 		void Decompress(ImageHeader h)

OpenRA.Game/FileFormats/ShpTSReader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -8,14 +8,13 @@
  */
 #endregion
 
-using System;
-using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
-using System.Linq;
 using OpenRA.Graphics;
 
 namespace OpenRA.FileFormats
+{
+	public class ShpTSReader : ISpriteSource
 	{
 		class FrameHeader : ISpriteFrame
 		{
@@ -44,11 +43,7 @@ namespace OpenRA.FileFormats
 			}
 		}
 
-	public class ShpTSReader : ISpriteSource
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-	{
-		readonly List<FrameHeader> frames = new List<FrameHeader>();
-		Lazy<IEnumerable<ISpriteFrame>> spriteFrames;
-		public IEnumerable<ISpriteFrame> Frames { get { return spriteFrames.Value; } }
 		public bool CacheWhenLoadingTileset { get { return false; } }
 
 		public ShpTSReader(Stream stream)
@@ -59,8 +54,10 @@ namespace OpenRA.FileFormats
 			var size = new Size(width, height);
 			var frameCount = stream.ReadUInt16();
 
-			for (var i = 0; i < frameCount; i++)
+			var frames = new FrameHeader[frameCount];
-				frames.Add(new FrameHeader(stream, size));
+			Frames = frames.AsReadOnly();
+			for (var i = 0; i < frames.Length; i++)
+				frames[i] = new FrameHeader(stream, size);
 
 			for (var i = 0; i < frameCount; i++)
 			{
@@ -70,14 +67,16 @@ namespace OpenRA.FileFormats
 
 				stream.Position = f.FileOffset;
 
+				var frameSize = f.Size.Width * f.Size.Height;
+
 				// Uncompressed
 				if (f.Format == 1 || f.Format == 0)
-					f.Data = stream.ReadBytes(f.Size.Width * f.Size.Height);
+					f.Data = stream.ReadBytes(frameSize);
 
 				// Uncompressed scanlines
 				else if (f.Format == 2)
 				{
-					f.Data = new byte[f.Size.Width * f.Size.Height];
+					f.Data = new byte[frameSize];
 					for (var j = 0; j < f.Size.Height; j++)
 					{
 						var length = stream.ReadUInt16() - 2;
@@ -89,17 +88,15 @@ namespace OpenRA.FileFormats
 				// RLE-zero compressed scanlines
 				else if (f.Format == 3)
 				{
-					f.Data = new byte[f.Size.Width * f.Size.Height];
+					f.Data = new byte[frameSize];
-
 					for (var j = 0; j < f.Size.Height; j++)
 					{
 						var length = stream.ReadUInt16() - 2;
-						Format2.DecodeInto(stream.ReadBytes(length), f.Data, j * f.Size.Width);
+						var offset = f.Size.Width * j;
+						Format2.DecodeInto(stream.ReadBytes(length), f.Data, offset);
 					}
 				}
 			}
-
-			spriteFrames = Exts.Lazy(() => frames.Cast<ISpriteFrame>());
 		}
 	}
 }

OpenRA.Game/FileFormats/TmpRAReader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -8,7 +8,6 @@
  */
 #endregion
 
-using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
 using OpenRA.Graphics;
@@ -17,8 +16,7 @@ namespace OpenRA.FileFormats
 {
 	public class TmpRAReader : ISpriteSource
 	{
-		readonly List<ISpriteFrame> tiles = new List<ISpriteFrame>();
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-		public IEnumerable<ISpriteFrame> Frames { get { return tiles; } }
 		public bool CacheWhenLoadingTileset { get { return false; } }
 
 		public TmpRAReader(Stream s)
@@ -35,15 +33,19 @@ namespace OpenRA.FileFormats
 			var indexStart = s.ReadInt32();
 
 			s.Position = indexStart;
-			foreach (var b in s.ReadBytes(indexEnd - indexStart))
+			var count = indexEnd - indexStart;
+			var tiles = new TmpTile[count];
+			Frames = tiles.AsReadOnly();
+			var tilesIndex = 0;
+			foreach (var b in s.ReadBytes(count))
 			{
 				if (b != 255)
 				{
 					s.Position = imgStart + b * width * height;
-					tiles.Add(new TmpTile(s.ReadBytes(width * height), size));
+					tiles[tilesIndex++] = new TmpTile(s.ReadBytes(width * height), size);
 				}
 				else
-					tiles.Add(new TmpTile(null, size));
+					tiles[tilesIndex++] = new TmpTile(null, size);
 			}
 		}
 	}

OpenRA.Game/FileFormats/TmpTDReader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -8,7 +8,6 @@
  */
 #endregion
 
-using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
 using OpenRA.Graphics;
@@ -36,8 +35,7 @@ namespace OpenRA.FileFormats
 
 	public class TmpTDReader : ISpriteSource
 	{
-		readonly List<ISpriteFrame> tiles = new List<ISpriteFrame>();
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-		public IEnumerable<ISpriteFrame> Frames { get { return tiles; } }
 		public bool CacheWhenLoadingTileset { get { return false; } }
 
 		public TmpTDReader(Stream s)
@@ -53,15 +51,19 @@ namespace OpenRA.FileFormats
 			var indexStart = s.ReadInt32();
 
 			s.Position = indexStart;
-			foreach (var b in s.ReadBytes(indexEnd - indexStart))
+			var count = indexEnd - indexStart;
+			var tiles = new TmpTile[count];
+			Frames = tiles.AsReadOnly();
+			var tilesIndex = 0;
+			foreach (var b in s.ReadBytes(count))
 			{
 				if (b != 255)
 				{
 					s.Position = imgStart + b * width * height;
-					tiles.Add(new TmpTile(s.ReadBytes(width * height), size));
+					tiles[tilesIndex++] = new TmpTile(s.ReadBytes(width * height), size);
 				}
 				else
-					tiles.Add(new TmpTile(null, size));
+					tiles[tilesIndex++] = new TmpTile(null, size);
 			}
 		}
 	}

OpenRA.Game/FileFormats/TmpTSReader.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2013 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -49,8 +49,7 @@ namespace OpenRA.FileFormats
 
 	public class TmpTSReader : ISpriteSource
 	{
-		readonly List<ISpriteFrame> tiles = new List<ISpriteFrame>();
+		public IReadOnlyList<ISpriteFrame> Frames { get; private set; }
-		public IEnumerable<ISpriteFrame> Frames { get { return tiles; } }
 		public bool CacheWhenLoadingTileset { get { return false; } }
 
 		public TmpTSReader(Stream s)
@@ -64,11 +63,14 @@ namespace OpenRA.FileFormats
 			for (var i = 0; i < offsets.Length; i++)
 				offsets[i] = s.ReadUInt32();
 
+			var tiles = new List<TmpTSTile>();
 			for (var i = 0; i < offsets.Length; i++)
 			{
 				s.Position = offsets[i];
 				tiles.Add(new TmpTSTile(s, size));
 			}
+
+			Frames = tiles.ToArray().AsReadOnly();
 		}
 	}
 }

OpenRA.Game/Graphics/SpriteSource.cs

@@ -1,6 +1,6 @@
 #region Copyright & License Information
 /*
- * Copyright 2007-2011 The OpenRA Developers (see AUTHORS)
+ * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
  * This file is part of OpenRA, which is free software. It is made
  * available to you under the terms of the GNU General Public License
  * as published by the Free Software Foundation. For more information,
@@ -8,7 +8,6 @@
  */
 #endregion
 
-using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
 using OpenRA.FileFormats;
@@ -25,8 +24,7 @@ namespace OpenRA.Graphics
 
 	public interface ISpriteSource
 	{
-		// TODO: Change this to IReadOnlyList so users don't need to call .ToArray()
+		IReadOnlyList<ISpriteFrame> Frames { get; }
-		IEnumerable<ISpriteFrame> Frames { get; }
 		bool CacheWhenLoadingTileset { get; }
 	}
 

OpenRA.Game/Primitives/ReadOnlyList.cs

@@ -21,12 +21,20 @@ namespace OpenRA
 	/// duplicate it but provide a compatible interface that can be replaced
 	/// when we switch to .NET 4.5 or higher.
 	/// </remarks>
-	public interface IReadOnlyList<T> : IEnumerable<T>
+	public interface IReadOnlyList<out T> : IEnumerable<T>
 	{
 		int Count { get; }
 		T this[int index] { get; }
 	}
 
+	public static class ReadOnlyList
+	{
+		public static IReadOnlyList<T> AsReadOnly<T>(this IList<T> list)
+		{
+			return list as IReadOnlyList<T> ?? new ReadOnlyList<T>(list);
+		}
+	}
+
 	/// <summary>
 	/// A minimal read only list for .NET 4 implemented as a wrapper
 	/// around an IList.

OpenRA.Utility/Command.cs

@@ -233,7 +233,7 @@ namespace OpenRA.Utility
 		{
 			var srcImage = ShpReader.Load(args[1]);
 
-			var srcFrames = srcImage.Frames.ToArray();
+			var srcFrames = srcImage.Frames;
 			var destFrames = srcImage.Frames.ToArray();
 
 			for (var z = 3; z < args.Length - 2; z += 3)