/**
* <summary>Retrieves the file information.</summary>
*/
public FileInfo ReadInfo(
)
{
//TODO:hybrid xref table/stream
Version version = Version.Get(parser.RetrieveVersion());
PdfDictionary trailer = null;
SortedDictionary <int, XRefEntry> xrefEntries = new SortedDictionary <int, XRefEntry>();
{
long sectionOffset = parser.RetrieveXRefOffset();
while (sectionOffset > -1)
{
// Move to the start of the xref section!
parser.Seek(sectionOffset);
PdfDictionary sectionTrailer;
if (parser.GetToken(1).Equals(Keyword.XRef)) // XRef-table section.
{
// Looping sequentially across the subsections inside the current xref-table section...
while (true)
{
/*
* NOTE: Each iteration of this block represents the scanning of one subsection.
* We get its bounds (first and last object numbers within its range) and then collect
* its entries.
*/
// 1. First object number.
parser.MoveNext();
if ((parser.TokenType == PostScriptParser.TokenTypeEnum.Keyword) &&
parser.Token.Equals(Keyword.Trailer)) // XRef-table section ended.
{
break;
}
else if (parser.TokenType != PostScriptParser.TokenTypeEnum.Integer)
{
throw new ParseException("Neither object number of the first object in this xref subsection nor end of xref section found.", parser.Position);
}
// Get the object number of the first object in this xref-table subsection!
int startObjectNumber = (int)parser.Token;
// 2. Last object number.
parser.MoveNext();
if (parser.TokenType != PostScriptParser.TokenTypeEnum.Integer)
{
throw new ParseException("Number of entries in this xref subsection not found.", parser.Position);
}
// Get the object number of the last object in this xref-table subsection!
int endObjectNumber = (int)parser.Token + startObjectNumber;
// 3. XRef-table subsection entries.
for (
int index = startObjectNumber;
index < endObjectNumber;
index++
)
{
if (xrefEntries.ContainsKey(index)) // Already-defined entry.
{
// Skip to the next entry!
parser.MoveNext(3);
continue;
}
// Get the indirect object offset!
int offset = (int)parser.GetToken(1);
// Get the object generation number!
int generation = (int)parser.GetToken(1);
// Get the usage tag!
XRefEntry.UsageEnum usage;
{
string usageToken = (string)parser.GetToken(1);
if (usageToken.Equals(Keyword.InUseXrefEntry))
{
usage = XRefEntry.UsageEnum.InUse;
}
else if (usageToken.Equals(Keyword.FreeXrefEntry))
{
usage = XRefEntry.UsageEnum.Free;
}
else
{
throw new ParseException("Invalid xref entry.", parser.Position);
}
}
// Define entry!
xrefEntries[index] = new XRefEntry(
index,
generation,
offset,
usage
);
}
}
// Get the previous trailer!
sectionTrailer = (PdfDictionary)parser.ParsePdfObject(1);
}
else // XRef-stream section.
{
XRefStream stream = (XRefStream)parser.ParsePdfObject(3); // Gets the xref stream skipping the indirect-object header.
// XRef-stream subsection entries.
foreach (XRefEntry xrefEntry in stream.Values)
{
if (xrefEntries.ContainsKey(xrefEntry.Number)) // Already-defined entry.
{
continue;
}
// Define entry!
xrefEntries[xrefEntry.Number] = xrefEntry;
}
// Get the previous trailer!
sectionTrailer = stream.Header;
}
if (trailer == null)
{
trailer = sectionTrailer;
}
// Get the previous xref-table section's offset!
PdfInteger prevXRefOffset = (PdfInteger)sectionTrailer[PdfName.Prev];
sectionOffset = (prevXRefOffset != null ? prevXRefOffset.IntValue : -1);
}
}
return(new FileInfo(version, trailer, xrefEntries));
}
