public IReadOnlyList <CosObject> Parse(PdfRawStream stream, CosObjectPool pool)
{
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
//need to first parse the header.
var numberOfObjects = stream.Dictionary.GetIntOrDefault(CosName.N);
var objectNumbers = new List <long>(numberOfObjects);
var streamObjects = new List <CosObject>(numberOfObjects);
var bytes = stream.Decode(filterProvider);
var reader = new RandomAccessBuffer(bytes);
for (int i = 0; i < numberOfObjects; i++)
{
long objectNumber = ObjectHelper.ReadObjectNumber(reader);
// skip offset
ReadHelper.ReadLong(reader);
objectNumbers.Add(objectNumber);
}
CosObject obj;
CosBase cosObject;
int objectCounter = 0;
while ((cosObject = baseParser.Parse(reader, pool)) != null)
{
obj = new CosObject(cosObject);
obj.SetGenerationNumber(0);
if (objectCounter >= objectNumbers.Count)
{
log.Error("/ObjStm (object stream) has more objects than /N " + numberOfObjects);
break;
}
obj.SetObjectNumber(objectNumbers[objectCounter]);
streamObjects.Add(obj);
// According to the spec objects within an object stream shall not be enclosed
// by obj/endobj tags, but there are some pdfs in the wild using those tags
// skip endobject marker if present
if (!reader.IsEof() && reader.Peek() == 'e')
{
ReadHelper.ReadLine(reader);
}
objectCounter++;
}
return(streamObjects);
}
/// <summary>
/// Parses through the unfiltered stream and populates the xrefTable HashMap.
/// </summary>
public CrossReferenceTablePart Parse(long streamOffset, PdfRawStream stream)
{
var w = stream.Dictionary.GetDictionaryObject(CosName.W);
if (!(w is COSArray format))
{
throw new IOException("/W array is missing in Xref stream");
}
var objNums = GetObjectNumbers(stream);
/*
* Calculating the size of the line in bytes
*/
int w0 = format.getInt(0);
int w1 = format.getInt(1);
int w2 = format.getInt(2);
int lineSize = w0 + w1 + w2;
var decoded = stream.Decode(filterProvider);
var lineCount = decoded.Length / lineSize;
var lineNumber = 0;
var builder = new CrossReferenceTablePartBuilder
{
Offset = streamOffset,
Previous = stream.Dictionary.GetLongOrDefault(CosName.PREV),
Dictionary = stream.Dictionary,
XRefType = CrossReferenceType.Stream
};
using (IEnumerator <long> objIter = objNums.GetEnumerator())
{
var currLine = new byte[lineSize];
while (lineNumber < lineCount && objIter.MoveNext())
{
var byteOffset = lineNumber * lineSize;
for (int i = 0; i < lineSize; i++)
{
currLine[i] = decoded[byteOffset + i];
}
int type;
if (w0 == 0)
{
// "If the first element is zero,
// the type field shall not be present, and shall default to type 1"
type = 1;
}
else
{
type = 0;
/*
* Grabs the number of bytes specified for the first column in
* the W array and stores it.
*/
for (int i = 0; i < w0; i++)
{
type += (currLine[i] & 0x00ff) << ((w0 - i - 1) * 8);
}
}
//Need to remember the current objID
long objectId = objIter.Current;
/*
* 3 different types of entries.
*/
switch (type)
{
case 0:
/*
* Skipping free objects
*/
break;
case 1:
int offset = 0;
for (int i = 0; i < w1; i++)
{
offset += (currLine[i + w0] & 0x00ff) << ((w1 - i - 1) * 8);
}
int genNum = 0;
for (int i = 0; i < w2; i++)
{
genNum += (currLine[i + w0 + w1] & 0x00ff) << ((w2 - i - 1) * 8);
}
builder.Add(objectId, genNum, offset);
break;
case 2:
/*
* object stored in object stream:
* 2nd argument is object number of object stream
* 3rd argument is index of object within object stream
*
* For sequential PDFParser we do not need this information
* because
* These objects are handled by the dereferenceObjects() method
* since they're only pointing to object numbers
*
* However for XRef aware parsers we have to know which objects contain
* object streams. We will store this information in normal xref mapping
* table but add object stream number with minus sign in order to
* distinguish from file offsets
*/
int objstmObjNr = 0;
for (int i = 0; i < w1; i++)
{
objstmObjNr += (currLine[i + w0] & 0x00ff) << ((w1 - i - 1) * 8);
}
builder.Add(objectId, 0, -objstmObjNr);
break;
}
lineNumber++;
}
}
return(builder.Build());
}