implemented Palette PACK2 archives, PGA and CHR images

ArcFormats/Palette/ImagePGA.cs

@@ -0,0 +1,79 @@
+//! \file       ImagePGA.cs
+//! \date       Mon Oct 26 06:38:07 2015
+//! \brief      Obfuscated PNG image.
+//
+// Copyright (C) 2015 by morkt
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to
+// deal in the Software without restriction, including without limitation the
+// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+// sell copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+// IN THE SOFTWARE.
+//
+
+using System.ComponentModel.Composition;
+using System.IO;
+
+namespace GameRes.Formats.Palette
+{
+    [Export(typeof(ImageFormat))]
+    public class PgaFormat : PngFormat
+    {
+        public override string         Tag { get { return "PGA"; } }
+        public override string Description { get { return "Palette obfuscated PNG image"; } }
+        public override uint     Signature { get { return 0x50414750; } } // 'PGAP'
+
+        public override ImageMetaData ReadMetaData (Stream stream)
+        {
+            using (var png = DeobfuscateStream (stream))
+                return base.ReadMetaData (png);
+        }
+
+        public override ImageData Read (Stream stream, ImageMetaData info)
+        {
+            using (var png = DeobfuscateStream (stream))
+                return base.Read (png, info);
+        }
+
+        public override void Write (Stream file, ImageData image)
+        {
+            using (var png = new MemoryStream())
+            {
+                base.Write (png, image);
+                var buffer = png.GetBuffer();
+                for (int i = 0; i < 8; ++i)
+                    buffer[i+8] ^= (byte)"PGAECODE"[i];
+                buffer[5] = (byte)'P';
+                buffer[6] = (byte)'G';
+                buffer[7] = (byte)'A';
+                file.Write (buffer, 5, (int)png.Length - 5);
+            }
+        }
+
+        public static readonly byte[] PngHeader = { 0x89, 0x50, 0x4E, 0x47, 0xD, 0xA, 0x1A, 0xA };
+        public static readonly byte[] PngFooter = { 0, 0, 0, 0, 0x49, 0x45, 0x4E, 0x44, 0xAE, 0x42, 0x60, 0x82 };
+
+        Stream DeobfuscateStream (Stream stream)
+        {
+            var png_header = new byte[0x10];
+            stream.Read (png_header, 5, 11);
+            System.Buffer.BlockCopy (PngHeader, 0, png_header, 0, 8);
+            for (int i = 0; i < 8; ++i)
+                png_header[i+8] ^= (byte)"PGAECODE"[i];
+            var png_body = new StreamRegion (stream, 11, true);
+            return new PrefixStream (png_header, png_body);
+        }
+    }
+}