private bool encryptionFeasible(FileModel fileModel, IImageWrapper container)
{
var spread = this.getByteSpread();
var numberOfChannels = Enum.GetValues(typeof(LosslessFileMuxxer.ByteOrder)).GetLength(0);
var totalBytesInImage = container.Width * container.Height * numberOfChannels;
var bytesAvailableForData = totalBytesInImage - EncryptionHeader.GetHeaderLength();
var bytesNeededForData = fileModel.FileContents.Length * spread;
return(bytesAvailableForData >= bytesNeededForData);
}
private FileModel demuxxImage(Pixel[,] source)
{
FileModel fileModel = null;
var numberOfChannels = Enum.GetValues(typeof(LosslessFileMuxxer.ByteOrder)).GetLength(0);
var sourceWidth = source.GetLength(0);
var sourceHeight = source.GetLength(1);
int byteSpread = this.getByteSpread();
int bitShiftCount = (BITS_PER_CHANNEL - BITS_USED_PER_CHANNEL);
int maxValue = (0x01 << BITS_PER_CHANNEL) - 0x01;
int partMask = maxValue >> bitShiftCount;
var spreadBytes = new byte[sourceWidth * sourceHeight * byteSpread];
var spreadIndex = 0;
var channelIndex = 0;
for (var x = 0; x < source.GetLength(0); ++x)
{
for (var y = 0; y < source.GetLength(1); ++y)
{
Pixel p = source [x, y];
for (var c = 0; c < numberOfChannels; ++c)
{
var channel = (ByteOrder)channelIndex;
byte valueToUse;
switch (channel)
{
case ByteOrder.Red:
valueToUse = (byte)(p.R & partMask);
break;
case ByteOrder.Green:
valueToUse = (byte)(p.G & partMask);
break;
case ByteOrder.Blue:
valueToUse = (byte)(p.B & partMask);
break;
default:
throw new NotImplementedException();
}
spreadBytes [spreadIndex] = valueToUse;
++spreadIndex;
channelIndex = channelIndex == numberOfChannels - 1 ? 0 : channelIndex + 1;
}
}
}
var unspreadBytes = new byte[sourceWidth * sourceHeight]; // don't yet know how many of these are useful yet
var unspreadIndex = 0;
spreadIndex = 0;
do
{
byte b = 0x00;
for (var i = 0; i < byteSpread; ++i)
{
var s = spreadBytes[spreadIndex];
var spreadShift = i * BITS_USED_PER_CHANNEL;
var shifted = s << spreadShift;
b += (byte)shifted;
++spreadIndex;
}
unspreadBytes[unspreadIndex] = b;
++unspreadIndex;
}while(spreadIndex < spreadBytes.Length);
var headerBytes = new byte[EncryptionHeader.GetHeaderLength()];
for (var i = 0; i < headerBytes.Length; ++i)
{
var h = unspreadBytes[i];
headerBytes [i] = h;
}
var header = new EncryptionHeader(headerBytes);
var fileBytes = unspreadBytes.Skip(headerBytes.Length).Take(header.FileSize).ToArray();
var ms = new MemoryStream(fileBytes);
ms.Position = 0;
fileModel = new FileModel(ms, header.FileName);
return(fileModel);
}