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(MG2): alternative encryption (#81)

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This commit is contained in:
morkt 2017-07-17 11:07:21 +04:00
parent ad16b754ae
commit 40575baacb
1 changed files with 91 additions and 28 deletions
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119
ArcFormats/Valkyria/ImageMG2.cs
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@ -23,6 +23,7 @@
// IN THE SOFTWARE.
//
using System;
using System.ComponentModel.Composition;
using System.IO;
using System.Windows.Media;
@ -32,8 +33,15 @@ namespace GameRes.Formats.Valkyria
{
internal class Mg2MetaData : ImageMetaData
{
public int ImageLength;
public int AlphaLength;
public int ImageLength;
public int AlphaLength;
public IMg2Scheme Scheme;
}
internal interface IMg2Scheme
{
Mg2EncryptedStream CreateStream (Stream main, int offset, int length);
ImageData CreateImage (BitmapSource bitmap, ImageMetaData info);
}
[Export(typeof(ImageFormat))]
@ -43,44 +51,54 @@ namespace GameRes.Formats.Valkyria
public override string Description { get { return "Valkyria image format"; } }
public override uint Signature { get { return 0x4F43494D; } } // 'MICO'
static readonly IMg2Scheme[] KnownSchemes = { new Mg2SchemeV1(), new Mg2SchemeV2() };
public override ImageMetaData ReadMetaData (IBinaryStream file)
{
var header = file.ReadHeader (0x10);
if (!header.AsciiEqual (4, "CG01"))
return null;
int length = header.ToInt32 (8);
using (var input = new Mg2EncryptedStream (file.AsStream, 0x10, length))
using (var png = new BinaryStream (input, file.Name))
foreach (var scheme in KnownSchemes)
{
var info = Png.ReadMetaData (png);
if (null == info)
return null;
return new Mg2MetaData
using (var input = scheme.CreateStream (file.AsStream, 0x10, length))
using (var png = new BinaryStream (input, file.Name))
{
Width = info.Width,
Height = info.Height,
OffsetX = info.OffsetX,
OffsetY = info.OffsetY,
BPP = info.BPP,
ImageLength = length,
AlphaLength = header.ToInt32 (12)
};
var info = Png.ReadMetaData (png);
if (null == info)
continue;
return new Mg2MetaData
{
Width = info.Width,
Height = info.Height,
OffsetX = info.OffsetX,
OffsetY = info.OffsetY,
BPP = info.BPP,
ImageLength = length,
AlphaLength = header.ToInt32 (12),
Scheme = scheme,
};
}
}
return null;
}
public override ImageData Read (IBinaryStream file, ImageMetaData info)
{
var meta = (Mg2MetaData)info;
var frame = ReadBitmapSource (file.AsStream, meta);
return meta.Scheme.CreateImage (frame, meta);
}
BitmapSource ReadBitmapSource (Stream file, Mg2MetaData meta)
{
BitmapSource frame;
using (var input = new Mg2EncryptedStream (file.AsStream, 0x10, meta.ImageLength))
using (var input = meta.Scheme.CreateStream (file, 0x10, meta.ImageLength))
{
var decoder = new PngBitmapDecoder (input, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
frame = decoder.Frames[0];
if (0 == meta.AlphaLength)
{
frame.Freeze();
return new ImageData (frame, info);
}
return frame;
}
if (frame.Format.BitsPerPixel != 32)
frame = new FormatConvertedBitmap (frame, PixelFormats.Bgr32, null, 0);
@ -88,12 +106,14 @@ namespace GameRes.Formats.Valkyria
var pixels = new byte[stride * (int)meta.Height];
frame.CopyPixels (pixels, stride, 0);
using (var input = new Mg2EncryptedStream (file.AsStream, 0x10+meta.ImageLength, meta.AlphaLength))
using (var input = meta.Scheme.CreateStream (file, 0x10+meta.ImageLength, meta.AlphaLength))
{
var decoder = new PngBitmapDecoder (input, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
BitmapSource alpha_frame = decoder.Frames[0];
if (alpha_frame.PixelWidth != frame.PixelWidth || alpha_frame.PixelHeight != frame.PixelHeight)
return ImageData.Create (info, PixelFormats.Bgr32, null, pixels, stride);
return BitmapSource.Create ((int)meta.Width, (int)meta.Height,
ImageData.DefaultDpiX, ImageData.DefaultDpiY,
PixelFormats.Bgr32, null, pixels, stride);
alpha_frame = new FormatConvertedBitmap (alpha_frame, PixelFormats.Gray8, null, 0);
var alpha = new byte[alpha_frame.PixelWidth * alpha_frame.PixelHeight];
@ -104,7 +124,9 @@ namespace GameRes.Formats.Valkyria
{
pixels[dst] = alpha[src++];
}
return ImageData.Create (info, PixelFormats.Bgra32, null, pixels, stride);
return BitmapSource.Create ((int)meta.Width, (int)meta.Height,
ImageData.DefaultDpiX, ImageData.DefaultDpiY,
PixelFormats.Bgra32, null, pixels, stride);
}
}
@ -117,11 +139,23 @@ namespace GameRes.Formats.Valkyria
internal class Mg2EncryptedStream : StreamRegion
{
readonly int m_threshold;
readonly byte m_key;
public Mg2EncryptedStream (Stream main, int offset, int length)
protected Mg2EncryptedStream (Stream main, int offset, int length, int threshold, byte key)
: base (main, offset, length, true)
{
m_threshold = length / 5;
m_threshold = threshold;
m_key = key;
}
public static Mg2EncryptedStream CreateV1 (Stream main, int offset, int length)
{
return new Mg2EncryptedStream (main, offset, length, length / 5, 0);
}
public static Mg2EncryptedStream CreateV2 (Stream main, int offset, int length)
{
return new Mg2EncryptedStream (main, offset, length, Math.Min (25, length), (byte)length);
}
public override int Read (byte[] buffer, int offset, int count)
@ -129,7 +163,7 @@ namespace GameRes.Formats.Valkyria
int pos = (int)Position;
int read = base.Read (buffer, offset, count);
for (int i = 0; i < read && pos < m_threshold; ++i)
buffer[offset+i] ^= (byte)pos++;
buffer[offset+i] ^= (byte)(m_key + pos++);
return read;
}
@ -138,8 +172,37 @@ namespace GameRes.Formats.Valkyria
long pos = Position;
int b = base.ReadByte();
if (b != -1 && pos < m_threshold)
b ^= (byte)pos;
b ^= (byte)(m_key + pos);
return b;
}
}
internal class Mg2SchemeV1 : IMg2Scheme
{
public Mg2EncryptedStream CreateStream (Stream main, int offset, int length)
{
return Mg2EncryptedStream.CreateV1 (main, offset, length);
}
public ImageData CreateImage (BitmapSource frame, ImageMetaData info)
{
frame.Freeze();
return new ImageData (frame, info);
}
}
internal class Mg2SchemeV2 : IMg2Scheme
{
public Mg2EncryptedStream CreateStream (Stream main, int offset, int length)
{
return Mg2EncryptedStream.CreateV2 (main, offset, length);
}
public ImageData CreateImage (BitmapSource frame, ImageMetaData info)
{
frame = new TransformedBitmap (frame, new ScaleTransform { ScaleY = -1 });
frame.Freeze();
return new ImageData (frame, info);
}
}
}