(VnMaker): Add support of ZIP MP3 OGG PNG formats.

ArcFormats/VnMaker/ImagePNG.cs

@@ -0,0 +1,61 @@
+using System.ComponentModel.Composition;
+using System.IO;
+
+namespace GameRes.Formats.VnMaker
+{
+    [Export(typeof(ImageFormat))]
+    public class PngFormat : GameRes.PngFormat
+    {
+        public override string         Tag { get { return "PNG/VnMaker Encrypted PNG Image"; } }
+        public override string Description { get { return "VnMaker Encrypted PNG Image"; } }
+        public override uint     Signature { get { return 0; } }
+        public override bool      CanWrite { get { return true; } }
+
+        public PngFormat() : base()
+        {
+            Signatures = new uint[] { 0 };
+            Extensions = new[] { "png" };
+        }
+
+        public override ImageMetaData ReadMetaData (IBinaryStream file)
+        {
+            using (var input = DeobfuscateStream (file, GuessEncryptionKey (file)))
+            {
+                if (input.Signature != 0x474E5089)
+                    throw new InvalidFormatException ();
+                return base.ReadMetaData (input);
+            }
+        }
+
+        public override ImageData Read (IBinaryStream file, ImageMetaData info)
+        {
+            using (var input = DeobfuscateStream (file, GuessEncryptionKey (file)))
+            {
+                if (input.Signature != 0x474E5089)
+                    throw new InvalidFormatException ();
+                return base.Read (input, info);
+            }
+        }
+
+        byte[] GuessEncryptionKey (IBinaryStream file)
+        {
+            return new byte[] { 0x0A, 0x2B, 0x36, 0x6F, 0x0B };
+        }
+
+        IBinaryStream DeobfuscateStream (IBinaryStream file, byte[] key)
+        {
+            var png = new ByteStringEncryptedStream (file.AsStream, key, true);
+            return new BinaryStream (png, file.Name);
+        }
+
+        public override void Write (Stream file, ImageData image)
+        {
+            var ms = new MemoryStream ();
+            base.Write (ms, image);
+            ms.Position = 0;
+            var es = new ByteStringEncryptedStream (ms, GuessEncryptionKey (null));
+            es.CopyTo (file);
+            file.Flush ();
+        }
+    }
+}