private static byte[] ReadBytes(PNGFile file, PNGScrambler scrambler, int count, int skip = 0)
{
scrambler.Reset();
List <byte> bits = new List <byte>();
int numBitsToRead = count * 8;
int pixelsToRead = numBitsToRead / 6 + ((numBitsToRead / 6.0) % 1.0 != 0 ? 1 : 0);
int pixelsToSkip = (skip * 8) / 6;
//int bitPairsToThrowaway = pixelsToSkip == 0 ? 0 : (6 - ((skip * 8) % 6)) / 2;
int bitPairsToThrowaway = ((skip * 8) % 6) / 2;
if (bitPairsToThrowaway == 2)
{
pixelsToRead++;
}
for (var x = 0; x < pixelsToSkip; x++)
{
scrambler.GetPixel();
}
for (var x = 0; x < pixelsToRead; x++)
{
PNGPixel p = scrambler.GetPixel();
bits.Add((byte)(p.Red & 0x03));
bits.Add((byte)(p.Green & 0x03));
bits.Add((byte)(p.Blue & 0x03));
}
for (var x = 0; x < bitPairsToThrowaway; x++)
{
bits.RemoveAt(0);
}
return(BitsToBytes(bits));
}
private static void EmbedData(byte[] data, PNGScrambler scrambler)
{
PNGPixel pix = null;
List <byte> bits = BytesToBits(data);
int channel = 3;
for (var x = 0; x < bits.Count; x++)
{
if (channel == 3)
{
pix = scrambler.GetPixel();
channel = 0;
}
switch (channel)
{
case 0:
pix.Red &= 0xFC;
pix.Red |= bits[x];
break;
case 1:
pix.Green &= 0xFC;
pix.Green |= bits[x];
break;
case 2:
pix.Blue &= 0xFC;
pix.Blue |= bits[x];
break;
}
channel++;
}
}
