public CrossReferenceTable Build(long startXrefOffset, ILog log)
{
CrossReferenceType type = CrossReferenceType.Table;
PdfDictionary trailerDictionary = new PdfDictionary();
Dictionary <CosObjectKey, long> objectOffsets = new Dictionary <CosObjectKey, long>();
List <long> xrefSeqBytePos = new List <long>();
var currentPart = parts.FirstOrDefault(x => x.Offset == startXrefOffset);
if (currentPart == null)
{
// no XRef at given position
log.Warn("Did not found XRef object at specified startxref position " + startXrefOffset);
// use all objects in byte position order (last entries overwrite previous ones)
xrefSeqBytePos.AddRange(parts.Select(x => x.Offset));
xrefSeqBytePos.Sort();
}
else
{
// copy xref type
type = currentPart.Type;
// found starting Xref object
// add this and follow chain defined by 'Prev' keys
xrefSeqBytePos.Add(startXrefOffset);
while (currentPart.Dictionary != null)
{
long prevBytePos = currentPart.Dictionary.GetLongOrDefault(CosName.PREV, -1L);
if (prevBytePos == -1)
{
break;
}
currentPart = parts.FirstOrDefault(x => x.Offset == prevBytePos);
if (currentPart == 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 >= parts.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)
{
var currentObject = parts.First(x => x.Offset == bPos);
if (currentObject.Dictionary != null)
{
foreach (var entry in currentObject.Dictionary)
{
/*
* If we're at a second trailer, we have a linearized pdf file, meaning that the first Size entry represents
* all of the objects so we don't need to grab the second.
*/
if (!entry.Key.Name.Equals("Size") ||
!trailerDictionary.ContainsKey(CosName.Create("Size")))
{
trailerDictionary.Set(entry.Key, entry.Value);
}
}
}
foreach (var item in currentObject.ObjectOffsets)
{
objectOffsets[item.Key] = item.Value;
}
}
return(new CrossReferenceTable(type, objectOffsets, trailerDictionary));
}
/**
* Set the value in the array as a name.
* @param index The index into the array.
* @param name The name to set in the array.
*/
public void setName(int index, string name)
{
set(index, CosName.Create(name));
}