/**
* Reset all data so that it can be used to rebuild the trailer.
*
*/
public void reset()
{
foreach (XrefTrailerObj trailerObj in bytePosToXrefMap.Values)
{
trailerObj.reset();
}
curXrefTrailerObj = null;
resolvedXrefTrailer = null;
}
/**
* Sets the byte position of the first XRef
* (has to be called after very last startxref was read).
* This is used to resolve chain of active XRef/trailer.
*
* In case startxref position is not found we output a
* warning and use all XRef/trailer objects combined
* in byte position order.
* Thus for incomplete PDF documents with missing
* startxref one could call this method with parameter value -1.
*
* @param startxrefBytePosValue starting position of the first XRef
*
*/
public void setStartxref(long startxrefBytePosValue)
{
if (resolvedXrefTrailer != null)
{
//LOG.warn("Method must be called only ones with last startxref value.");
return;
}
resolvedXrefTrailer = new XrefTrailerObj {
trailer = new CosDictionary()
};
bytePosToXrefMap.TryGetValue(startxrefBytePosValue, out XrefTrailerObj curObj);
List <long> xrefSeqBytePos = new List <long>();
if (curObj == null)
{
// no XRef at given position
//LOG.warn("Did not found XRef object at specified startxref position " + startxrefBytePosValue);
// use all objects in byte position order (last entries overwrite previous ones)
xrefSeqBytePos.AddRange(bytePosToXrefMap.Keys);
xrefSeqBytePos.Sort();
}
else
{
// copy xref type
resolvedXrefTrailer.xrefType = curObj.xrefType;
// found starting Xref object
// add this and follow chain defined by 'Prev' keys
xrefSeqBytePos.Add(startxrefBytePosValue);
while (curObj.trailer != null)
{
long prevBytePos = curObj.trailer.getLong(CosName.PREV, -1L);
if (prevBytePos == -1)
{
break;
}
bytePosToXrefMap.TryGetValue(prevBytePos, out curObj);
if (curObj == null)
{
//LOG.warn("Did not found XRef object pointed to by 'Prev' key at position " + prevBytePos);
break;
}
xrefSeqBytePos.Add(prevBytePos);
// sanity check to prevent infinite loops
if (xrefSeqBytePos.Count >= bytePosToXrefMap.Count)
{
break;
}
}
// have to reverse order so that later XRefs will overwrite previous ones
xrefSeqBytePos.Reverse();
}
// merge used and sorted XRef/trailer
foreach (long bPos in xrefSeqBytePos)
{
bytePosToXrefMap.TryGetValue(bPos, out curObj);
if (curObj.trailer != null)
{
resolvedXrefTrailer.trailer.addAll(curObj.trailer);
}
foreach (var item in curObj.xrefTable)
{
resolvedXrefTrailer.xrefTable[item.Key] = item.Value;
}
}
}
/**
* Signals that a new XRef object (table or stream) starts.
* @param startBytePos the offset to start at
* @param type the type of the Xref object
*/
public void nextXrefObj(long startBytePos, XRefType type)
{
bytePosToXrefMap[startBytePos] = curXrefTrailerObj = new XrefTrailerObj();
curXrefTrailerObj.xrefType = type;
}
