implemented PNX images.

ArcFormats/ArcFormats.csproj

@@ -111,6 +111,7 @@
     <Compile Include="Foster\ImageC25.cs" />
     <Compile Include="GameSystem\ArcPureMail.cs" />
     <Compile Include="GameSystem\AudioADP4.cs" />
+    <Compile Include="ImagePNX.cs" />
     <Compile Include="ImagePSM.cs" />
     <Compile Include="Kaas\ArcPB.cs" />
     <Compile Include="Kaas\AudioKAAS.cs" />

ArcFormats/ImagePNX.cs

@@ -0,0 +1,67 @@
+//! \file       ImagePNX.cs
+//! \date       2017 Nov 21
+//! \brief      Encrypted PNG image.
+//
+// Copyright (C) 2017 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.Misc
+{
+    [Export(typeof(ImageFormat))]
+    public class PnxFormat : PngFormat
+    {
+        public override string         Tag { get { return "PNX"; } }
+        public override string Description { get { return "Encrypted PNG image"; } }
+        public override uint     Signature { get { return 0x2F2638E1; } }
+        public override bool      CanWrite { get { return false; } }
+
+        public override ImageMetaData ReadMetaData (IBinaryStream file)
+        {
+            using (var input = DeobfuscateStream (file, GuessEncryptionKey (file)))
+                return base.ReadMetaData (input);
+        }
+
+        public override ImageData Read (IBinaryStream file, ImageMetaData info)
+        {
+            using (var input = DeobfuscateStream (file, GuessEncryptionKey (file)))
+                return base.Read (input, info);
+        }
+
+        byte GuessEncryptionKey (IBinaryStream file)
+        {
+            return (byte)(file.Signature ^ 0x89);
+        }
+
+        IBinaryStream DeobfuscateStream (IBinaryStream file, byte key)
+        {
+            var png = new XoredStream (file.AsStream, key, true);
+            return new BinaryStream (png, file.Name);
+        }
+
+        public override void Write (Stream file, ImageData image)
+        {
+            throw new System.NotImplementedException ("PnxFormat.Write not implemented");
+        }
+    }
+}