private static void ReadFromDecoderStream(CcittFaxDecoderStream decoderStream, byte[] result)
{
var pos = 0;
int read;
while ((read = decoderStream.Read(result, pos, result.Length - pos)) > -1)
{
pos += read;
if (pos >= result.Length)
{
break;
}
}
decoderStream.Close();
}
/// <inheritdoc />
public byte[] Decode(IReadOnlyList <byte> input, DictionaryToken streamDictionary, int filterIndex)
{
var decodeParms = DecodeParameterResolver.GetFilterParameters(streamDictionary, filterIndex);
var cols = decodeParms.GetIntOrDefault(NameToken.Columns, 1728);
var rows = decodeParms.GetIntOrDefault(NameToken.Rows, 0);
var height = streamDictionary.GetIntOrDefault(NameToken.Height, NameToken.H, 0);
if (rows > 0 && height > 0)
{
// PDFBOX-771, PDFBOX-3727: rows in DecodeParms sometimes contains an incorrect value
rows = height;
}
else
{
// at least one of the values has to have a valid value
rows = Math.Max(rows, height);
}
var k = decodeParms.GetIntOrDefault(NameToken.K, 0);
var encodedByteAlign = decodeParms.GetBooleanOrDefault(NameToken.EncodedByteAlign, false);
var compressionType = DetermineCompressionType(input, k);
using (var stream = new CcittFaxDecoderStream(new MemoryStream(input.ToArray()), cols, compressionType, encodedByteAlign))
{
var arraySize = (cols + 7) / 8 * rows;
var decompressed = new byte[arraySize];
ReadFromDecoderStream(stream, decompressed);
// we expect black to be 1, if not invert the bitmap
var blackIsOne = decodeParms.GetBooleanOrDefault(NameToken.BlackIs1, false);
if (!blackIsOne)
{
InvertBitmap(decompressed);
}
return(decompressed);
}
}
