private NetpbmHeader <TPixelFormat> ReadPGMOrPPMHeader <TPixelFormat>(Stream stream, ValueEncoding valueEncoding, IImageFactory <TPixelFormat> imageFactory, params Component[] components)
{
int width;
var widthBytes = SkipWhitespaceAndReadUntilNextWhitespaceByte(stream, true);
var widthString = GetUsAsciiString(widthBytes);
if (!TryParseIntInvariant(widthString, out width))
{
throw new InvalidDataException(string.Format("failed to parse width '{0}'", widthString));
}
int height;
var heightBytes = SkipWhitespaceAndReadUntilNextWhitespaceByte(stream, true);
var heightString = GetUsAsciiString(heightBytes);
if (!TryParseIntInvariant(heightString, out height))
{
throw new InvalidDataException(string.Format("failed to parse height '{0}'", heightString));
}
var highestValueBytes = SkipWhitespaceAndReadUntilNextWhitespaceByte(stream, true);
var highestValueString = GetUsAsciiString(highestValueBytes);
TPixelFormat highestValue = imageFactory.ParseHighestComponentValue(highestValueString);
// final byte of whitespace has been discarded by SkipWhitespaceAndReadUntilNextWhitespaceByte
return(new NetpbmHeader <TPixelFormat>(
(components.Length == 1)
? ((valueEncoding == ValueEncoding.Binary) ? ImageType.PGM : ImageType.PlainPGM)
: ((valueEncoding == ValueEncoding.Binary) ? ImageType.PPM : ImageType.PlainPPM),
width,
height,
imageFactory.GetNumberOfBytesPerPixelComponent(highestValue),
components,
highestValue
));
//return imageFactory.MakeImage(width, height, highestValue, components, rows);
}
private NetpbmHeader <TPixelFormat> ReadPAMHeader <TPixelFormat>(Stream stream, IImageFactory <TPixelFormat> imageFactory)
{
// ensure the next character is a newline
var newline = stream.ReadByte();
if (newline == -1)
{
throw new EndOfStreamException();
}
else if (newline != '\n')
{
throw new InvalidDataException("byte after magic is not a newline");
}
int? width = null;
int? height = null;
int? depth = null;
string maxValueString = null;
string tupleType = "";
bool headerEnded = false;
while (!headerEnded)
{
var lineBytes = ReadUntilAndDiscardNewline(stream, true);
var lineString = GetUsAsciiString(lineBytes);
if (lineString.Length == 0)
{
// empty line
continue;
}
if (lineString[0] == '#')
{
// comment
continue;
}
string keyword, value;
SplitKeywordAndValue(lineString, out keyword, out value);
int intValue;
switch (keyword.ToUpperInvariant())
{
case "WIDTH":
if (value == null)
{
throw new InvalidDataException("PAM header field WIDTH is missing a value");
}
if (!TryParseIntInvariant(value, out intValue))
{
throw new InvalidDataException(string.Format("failed to parse width '{0}'", value));
}
width = intValue;
break;
case "HEIGHT":
if (value == null)
{
throw new InvalidDataException("PAM header field HEIGHT is missing a value");
}
if (!TryParseIntInvariant(value, out intValue))
{
throw new InvalidDataException(string.Format("failed to parse height '{0}'", value));
}
height = intValue;
break;
case "DEPTH":
if (value == null)
{
throw new InvalidDataException("PAM header field DEPTH is missing a value");
}
if (!TryParseIntInvariant(value, out intValue))
{
throw new InvalidDataException(string.Format("failed to parse depth '{0}'", value));
}
depth = intValue;
break;
case "MAXVAL":
if (value == null)
{
throw new InvalidDataException("PAM header field MAXVAL is missing a value");
}
maxValueString = value;
break;
case "TUPLTYPE":
if (value == null)
{
// never mind
}
else if (tupleType.Length == 0)
{
tupleType = value;
}
else
{
tupleType += " " + value;
}
break;
case "ENDHDR":
headerEnded = true;
break;
}
}
if (!width.HasValue)
{
throw new InvalidDataException("PAM header missing width");
}
if (!height.HasValue)
{
throw new InvalidDataException("PAM header missing height");
}
if (!depth.HasValue)
{
throw new InvalidDataException("PAM header missing depth");
}
if (maxValueString == null)
{
throw new InvalidDataException("PAM header missing maximum value");
}
// don't worry if the tuple type is missing
var maxValue = imageFactory.ParseHighestComponentValue(maxValueString);
var bytesPerComponent = imageFactory.GetNumberOfBytesPerPixelComponent(maxValue);
var components = KnownTupleTypes.DecodeComponentString(tupleType).ToList();
if (components.Count != depth.Value)
{
throw new InvalidDataException("component count doesn't match depth");
}
// final newline has been discarded by ReadUntilAndDiscardNewline
return(new NetpbmHeader <TPixelFormat>(
(bytesPerComponent > 2) ? ImageType.BigPAM : ImageType.PAM,
width.Value,
height.Value,
bytesPerComponent,
components,
maxValue
));
}
