/// <summary>
/// Main constructor for PNGFile.
/// </summary>
/// <param name="path">Path to the PNG file to be loaded.</param>
public PNGFile(string path)
{
originalFile = path;
var reader = FileHelper.CreatePngReader(path);
if (reader.ImgInfo.BitDepth != 8 || reader.ImgInfo.Channels < 3)
{
throw new ArgumentException("The PNG file must be an 24/32 bit PNG file, 8bit channels and RGB/A");
}
this.ImgInfo = reader.ImgInfo;
reader.ShouldCloseStream = true;
hasAlpha = reader.ImgInfo.Alpha;
for (var x = 0; x < reader.ImgInfo.Rows; x++)
{
PNGPixel[] line = new PNGPixel[reader.ImgInfo.Cols];
byte[] scanLine = reader.ReadRowByte(x).ScanlineB;
int bytesPerPixel = hasAlpha ? 4 : 3;
int byteCount = 0;
int pixelCount = 0;
PNGPixel curPixel = new PNGPixel();
for (var y = 0; y < scanLine.Length; y++)
{
byteCount++;
if (byteCount > bytesPerPixel || y == (scanLine.Length - 1))
{
line[pixelCount++] = curPixel;
byteCount = 1;
curPixel = new PNGPixel();
}
if (byteCount == 1)
{
curPixel.Red = scanLine[y];
}
else if (byteCount == 2)
{
curPixel.Green = scanLine[y];
}
else if (byteCount == 3)
{
curPixel.Blue = scanLine[y];
}
else if (byteCount == 4)
{
curPixel.Alpha = scanLine[y];
}
}
lines.Add(line);
}
reader.End();
reader = null;
}
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++;
}
}
