Move Png loader back to OpenRA.Game.

OpenRA.Game/FileFormats/Png.cs

@@ -0,0 +1,205 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2018 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, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.IO;
+using System.IO.Compression;
+using System.Linq;
+using System.Net;
+using System.Text;
+
+namespace OpenRA.FileFormats
+{
+	public class Png
+	{
+		public int Width { get; set; }
+		public int Height { get; set; }
+		public PixelFormat PixelFormat { get; set; }
+		public Color[] Palette { get; set; }
+		public byte[] Data { get; set; }
+		public Dictionary<string, string> EmbeddedData = new Dictionary<string, string>();
+
+		public Png(Stream s)
+		{
+			if (!Verify(s))
+				throw new InvalidDataException("PNG Signature is bogus");
+
+			s.Position += 8;
+			var headerParsed = false;
+
+			var data = new List<byte>();
+
+			for (;;)
+			{
+				var length = IPAddress.NetworkToHostOrder(s.ReadInt32());
+				var type = Encoding.UTF8.GetString(s.ReadBytes(4));
+				var content = s.ReadBytes(length);
+				/*var crc = */s.ReadInt32();
+
+				if (!headerParsed && type != "IHDR")
+					throw new InvalidDataException("Invalid PNG file - header does not appear first.");
+
+				using (var ms = new MemoryStream(content))
+				{
+					switch (type)
+					{
+						case "IHDR":
+						{
+							if (headerParsed)
+								throw new InvalidDataException("Invalid PNG file - duplicate header.");
+							Width = IPAddress.NetworkToHostOrder(ms.ReadInt32());
+							Height = IPAddress.NetworkToHostOrder(ms.ReadInt32());
+							Data = new byte[Width * Height];
+
+							var bitDepth = ms.ReadUInt8();
+							var colorType = (PngColorType)ms.ReadByte();
+							PixelFormat = MakePixelFormat(bitDepth, colorType);
+
+							var compression = ms.ReadByte();
+							/*var filter = */ms.ReadByte();
+							var interlace = ms.ReadByte();
+
+							if (compression != 0)
+								throw new InvalidDataException("Compression method not supported");
+
+							if (interlace != 0)
+								throw new InvalidDataException("Interlacing not supported");
+
+							headerParsed = true;
+
+							break;
+						}
+
+						case "PLTE":
+						{
+							Palette = new Color[256];
+							for (var i = 0; i < length / 3; i++)
+							{
+								var r = ms.ReadByte(); var g = ms.ReadByte(); var b = ms.ReadByte();
+								Palette[i] = Color.FromArgb(r, g, b);
+							}
+
+							break;
+						}
+
+						case "tRNS":
+						{
+							if (Palette == null)
+								throw new InvalidDataException("Non-Palette indexed PNG are not supported.");
+
+							for (var i = 0; i < length; i++)
+								Palette[i] = Color.FromArgb(ms.ReadByte(), Palette[i]);
+
+							break;
+						}
+
+						case "IDAT":
+						{
+							data.AddRange(content);
+
+							break;
+						}
+
+						case "tEXt":
+						{
+							var key = ms.ReadASCIIZ();
+							EmbeddedData.Add(key, ms.ReadASCII(length - key.Length - 1));
+
+							break;
+						}
+
+						case "IEND":
+						{
+							using (var ns = new MemoryStream(data.ToArray()))
+							{
+								// 'zlib' flags bytes; confuses the DeflateStream.
+								/*var flags = (byte)*/ns.ReadByte();
+								/*var moreFlags = (byte)*/ns.ReadByte();
+
+								using (var ds = new DeflateStream(ns, CompressionMode.Decompress))
+								{
+									var prevLine = new byte[Width];  // all zero
+									for (var y = 0; y < Height; y++)
+									{
+										var filter = (PngFilter)ds.ReadByte();
+										var line = ds.ReadBytes(Width);
+
+										for (var i = 0; i < Width; i++)
+											line[i] = i > 0
+												? UnapplyFilter(filter, line[i], line[i - 1], prevLine[i], prevLine[i - 1])
+												: UnapplyFilter(filter, line[i], 0, prevLine[i], 0);
+
+										Array.Copy(line, 0, Data, y * Width, line.Length);
+										prevLine = line;
+									}
+								}
+							}
+
+							if (Palette == null)
+								throw new InvalidDataException("Non-Palette indexed PNG are not supported.");
+
+							return;
+						}
+					}
+				}
+			}
+		}
+
+		public static bool Verify(Stream s)
+		{
+			var pos = s.Position;
+			var signature = new[] { 0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a };
+			var isPng = signature.Aggregate(true, (current, t) => current && s.ReadUInt8() == t);
+			s.Position = pos;
+			return isPng;
+		}
+
+		static byte UnapplyFilter(PngFilter f, byte x, byte a, byte b, byte c)
+		{
+			switch (f)
+			{
+				case PngFilter.None: return x;
+				case PngFilter.Sub: return (byte)(x + a);
+				case PngFilter.Up: return (byte)(x + b);
+				case PngFilter.Average: return (byte)(x + (a + b) / 2);
+				case PngFilter.Paeth: return (byte)(x + Paeth(a, b, c));
+				default:
+					throw new InvalidOperationException("Unsupported Filter");
+			}
+		}
+
+		static byte Paeth(byte a, byte b, byte c)
+		{
+			var p = a + b - c;
+			var pa = Math.Abs(p - a);
+			var pb = Math.Abs(p - b);
+			var pc = Math.Abs(p - c);
+
+			return (pa <= pb && pa <= pc) ? a :
+				(pb <= pc) ? b : c;
+		}
+
+		[Flags]
+		enum PngColorType { Indexed = 1, Color = 2, Alpha = 4 }
+		enum PngFilter { None, Sub, Up, Average, Paeth }
+
+		static PixelFormat MakePixelFormat(byte bitDepth, PngColorType colorType)
+		{
+			if (bitDepth == 8 && colorType == (PngColorType.Indexed | PngColorType.Color))
+				return PixelFormat.Format8bppIndexed;
+
+			throw new InvalidDataException("Unknown pixel format");
+		}
+	}
+}

OpenRA.Game/OpenRA.Game.csproj

@@ -104,6 +104,7 @@
     <Compile Include="Activities\CallFunc.cs" />
     <Compile Include="Actor.cs" />
     <Compile Include="CacheStorage.cs" />
+    <Compile Include="FileFormats\Png.cs" />
     <Compile Include="FileSystem\IPackage.cs" />
     <Compile Include="Primitives\Int32Matrix4x4.cs" />
     <Compile Include="LogProxy.cs" />