(Legacy): GRA images.

Legacy/Kurumi/ImageGRA.cs

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+//! \file       ImageGRA.cs
+//! \date       2019 Feb 27
+//! \brief      Kurumi encrypted image.
+//
+// Copyright (C) 2019 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;
+using System.ComponentModel.Composition;
+using System.IO;
+using System.Windows.Media;
+
+// [000324][Kurumi] 4m
+
+namespace GameRes.Formats.Kurumi
+{
+    [Export(typeof(ImageFormat))]
+    public class GraFormat : ImageFormat
+    {
+        public override string         Tag { get { return "GRA/KURUMI"; } }
+        public override string Description { get { return "Kurumi encrypted image"; } }
+        public override uint     Signature { get { return 0xEE2FA397; } }
+
+        public override ImageMetaData ReadMetaData (IBinaryStream file)
+        {
+            var header = file.ReadHeader (0x14).ToArray();
+            Decrypt (header);
+            if (header.ToInt32 (0) != 0x10)
+                return null;
+            return new ImageMetaData {
+                Width  = header.ToUInt16 (0x10),
+                Height = header.ToUInt16 (0x12),
+                OffsetX = header.ToInt16 (0xC),
+                OffsetY = header.ToInt16 (0xE),
+                BPP = 16,
+            };
+        }
+
+        public override ImageData Read (IBinaryStream file, ImageMetaData info)
+        {
+            var data = file.ReadBytes ((int)file.Length);
+            Decrypt (data);
+            var pixels = new byte[info.iWidth * info.iHeight * 2];
+            int src = 0x14;
+            int dst = 0;
+            while (dst < pixels.Length)
+            {
+                byte p0 = data[src++];
+                byte p1 = data[src++];
+                pixels[dst++] = (byte)((p1 >> 2) & 0x1F | p0 & 0xE0);
+                pixels[dst++] = (byte)((p0 & 0x1F) << 2 | p1 & 3);
+            }
+            return ImageData.Create (info, PixelFormats.Bgr555, null, pixels);
+        }
+
+        public override void Write (Stream file, ImageData image)
+        {
+            throw new System.NotImplementedException ("GraFormat.Write not implemented");
+        }
+
+        void Decrypt (byte[] data)
+        {
+            int seed = 34567;
+            for (int i = 0; i < data.Length; ++i)
+            {
+                data[i] -= (byte)(seed >> 8);
+                seed = 5 * seed - 1;
+            }
+        }
+    }
+}