public override bool Parse(JpegParser dataReader)
{
if (!base.Parse(dataReader))
{
return(false);
}
JpegParser jpegDataReader = dataReader as JpegParser;
jpegDataReader.GetUShort(Attribute.Length, "{0:X4}");
jpegDataReader.GetFourCC(Attribute.Identifier);
jpegDataReader.DataReader.GetByte(); // =0
jpegDataReader.GetUShort(Attribute.Version, "{0:X4}");
jpegDataReader.GetByte(Attribute.Units);
jpegDataReader.GetUShort(Attribute.XDensity);
jpegDataReader.GetUShort(Attribute.YDensity);
int xThumbnail = jpegDataReader.GetByte(Attribute.XThumbnail);
int yThumbnail = jpegDataReader.GetByte(Attribute.YThumbnail);
// The following parameter shows that data from previous parameters can
// be used to calculate other parameters, such as header lengths etc.
int rgbLength = 3 * xThumbnail * yThumbnail;
// As the actual byte data might be large, a placeholder string is used instead
Attributes.Add(new FormattedAttribute <Attribute, string>(Attribute.RGBn, "<RGB values for thumbnail>"));
// Increment the Position for the packed RGB values of the thumbnail
jpegDataReader.DataReader.Position += rgbLength;
return(this.Valid);
}
/// <summary>
/// Search for headers in the data and store the results.
/// </summary>
/// <param name="dataReader">the data to read the bytes and bits from</param>
public IResultNode DetectData(IDataReader dataReader, IDetectionProperties properties)
{
JpegHeader root = new JpegHeader(this);
using (JpegParser parser = new JpegParser(dataReader))
{
JpegHeader previousHeader = root;
ushort marker;
while ((marker = parser.NextMarker()) != 0)
{
JpegHeader header = HeaderForMarker(marker, previousHeader);
if (header != null && header.HeaderName == JpegHeaderName.StartOfImage && root.Children.Count > 0)
{
root.Children.Clear();
}
if (header != null && parser.Parse(header))
{
previousHeader = header;
if (IsFullFile(root))
{
break;
}
}
else
{
parser.DataReader.Position++;
}
}
}
if (dataReader.State == DataReaderState.Cancelled || !IsFullFile(root))
{
root = null;
}
else
{
properties.DataFormat = CodecID.Jpeg;
properties.IsFullFile = true;
}
return(root);
}