public IEnumerable <BigInteger> ReadRow(Stream stream, int width, int componentCount, BigInteger highestComponentValue)
{
var bytesPerValue = GetNumberOfBytesPerPixelComponent(highestComponentValue);
var readCount = width * componentCount;
var ret = new List <BigInteger>();
var buf = new byte[bytesPerValue];
for (int i = 0; i < readCount; ++i)
{
if (!NetpbmUtil.ReadToFillBuffer(stream, buf))
{
throw new EndOfStreamException();
}
// values are big endian, BigInteger wants little
Array.Reverse(buf);
// is the potential sign bit set?
if ((buf[buf.Length - 1] & 0x80) != 0)
{
// add a zero byte at the end to make sure the number is positive
var newBuf = new byte[buf.Length + 1];
Array.Copy(buf, 0, newBuf, 0, buf.Length);
newBuf[buf.Length] = 0;
ret.Add(new BigInteger(newBuf));
}
else
{
ret.Add(new BigInteger(buf));
}
}
return(ret);
}
private IEnumerable <TPixelFormat> ReadBinaryPBMRow <TPixelFormat>(Stream stream, int pixelCount, IImageFactory <TPixelFormat> imageFactory)
{
int byteCount = pixelCount / 8;
if (pixelCount % 8 != 0)
{
++byteCount;
}
var rowBytes = new byte[byteCount];
if (!NetpbmUtil.ReadToFillBuffer(stream, rowBytes))
{
throw new EndOfStreamException();
}
for (int i = 0; i < pixelCount; ++i)
{
var byteOffset = i / 8;
// leftmost bit is the top bit
var bitShift = 7 - (i % 8);
if ((rowBytes[byteOffset] & (1 << bitShift)) == 0)
{
yield return(imageFactory.ZeroPixelComponentValue);
}
else
{
yield return(imageFactory.BitmapOnPixelComponentValue);
}
}
}
public IEnumerable <byte> ReadRow(Stream stream, int width, int componentCount, byte highestComponentValue)
{
var readCount = width * componentCount;
var ret = new byte[readCount];
if (!NetpbmUtil.ReadToFillBuffer(stream, ret))
{
throw new EndOfStreamException();
}
return(ret);
}
public IEnumerable <ushort> ReadRow(Stream stream, int width, int componentCount, ushort highestComponentValue)
{
var readCount = width * componentCount;
var ret = new List <ushort>();
var buf = new byte[2];
for (int i = 0; i < readCount; ++i)
{
if (!NetpbmUtil.ReadToFillBuffer(stream, buf))
{
throw new EndOfStreamException();
}
// big-endian
ushort val = (ushort)(
((uint)buf[0] << 8) |
((uint)buf[1] << 0)
);
ret.Add(val);
}
return(ret);
}
