protected internal virtual byte[] DecodeFlateBytes(PdfStream stream, byte[] bytes)
{
PdfObject filterObject = stream.Get(PdfName.Filter);
if (filterObject == null)
{
return(bytes);
}
// check if flateDecode filter is on top
PdfName filterName;
PdfArray filtersArray = null;
if (filterObject is PdfName)
{
filterName = (PdfName)filterObject;
}
else
{
if (filterObject is PdfArray)
{
filtersArray = (PdfArray)filterObject;
filterName = filtersArray.GetAsName(0);
}
else
{
throw new PdfException(PdfException.FilterIsNotANameOrArray);
}
}
if (!PdfName.FlateDecode.Equals(filterName))
{
return(bytes);
}
// get decode params if present
PdfDictionary decodeParams;
PdfArray decodeParamsArray = null;
PdfObject decodeParamsObject = stream.Get(PdfName.DecodeParms);
if (decodeParamsObject == null)
{
decodeParams = null;
}
else
{
if (decodeParamsObject.GetObjectType() == PdfObject.DICTIONARY)
{
decodeParams = (PdfDictionary)decodeParamsObject;
}
else
{
if (decodeParamsObject.GetObjectType() == PdfObject.ARRAY)
{
decodeParamsArray = (PdfArray)decodeParamsObject;
decodeParams = decodeParamsArray.GetAsDictionary(0);
}
else
{
throw new PdfException(PdfException.DecodeParameterType1IsNotSupported).SetMessageParams(decodeParamsObject
.GetType().ToString());
}
}
}
// decode
byte[] res = FlateDecodeFilter.FlateDecode(bytes, true);
if (res == null)
{
res = FlateDecodeFilter.FlateDecode(bytes, false);
}
bytes = FlateDecodeFilter.DecodePredictor(res, decodeParams);
//remove filter and decode params
filterObject = null;
if (filtersArray != null)
{
filtersArray.Remove(0);
if (filtersArray.Size() == 1)
{
filterObject = filtersArray.Get(0);
}
else
{
if (!filtersArray.IsEmpty())
{
filterObject = filtersArray;
}
}
}
decodeParamsObject = null;
if (decodeParamsArray != null)
{
decodeParamsArray.Remove(0);
if (decodeParamsArray.Size() == 1 && decodeParamsArray.Get(0).GetObjectType() != PdfObject.NULL)
{
decodeParamsObject = decodeParamsArray.Get(0);
}
else
{
if (!decodeParamsArray.IsEmpty())
{
decodeParamsObject = decodeParamsArray;
}
}
}
if (filterObject == null)
{
stream.Remove(PdfName.Filter);
}
else
{
stream.Put(PdfName.Filter, filterObject);
}
if (decodeParamsObject == null)
{
stream.Remove(PdfName.DecodeParms);
}
else
{
stream.Put(PdfName.DecodeParms, decodeParamsObject);
}
return(bytes);
}