protected override void WriteStandard()
{
// 1. Header [PDF:1.6:3.4.1].
WriteHeader();
// 2. Body [PDF:1.6:3.4.2].
int xrefSize = file.IndirectObjects.Count;
StringBuilder xrefBuilder = new StringBuilder(XRefChunk);
{
/*
* NOTE: A standard xref table comprises just one section composed by just one subsection.
* NOTE: As xref-table free entries MUST be arrayed as a linked list,
* it's needed to cache intermingled in-use entries in order to properly render
* the object number of the next free entry inside the previous one.
*/
AppendXRefSubsectionIndexer(xrefBuilder, 0, xrefSize);
StringBuilder xrefInUseBlockBuilder = new StringBuilder();
IndirectObjects indirectObjects = file.IndirectObjects;
PdfReference freeReference = indirectObjects[0].Reference; // Initialized to the first free entry.
for (int index = 1; index < xrefSize; index++)
{
// Current entry insertion.
PdfIndirectObject indirectObject = indirectObjects[index];
if (indirectObject.IsInUse()) // In-use entry.
{
// Add in-use entry!
AppendXRefEntry(xrefInUseBlockBuilder, indirectObject.Reference, stream.Length);
// Add in-use entry content!
indirectObject.WriteTo(stream, file);
}
else // Free entry.
{
// Add free entry!
AppendXRefEntry(xrefBuilder, freeReference, index);
// End current block!
xrefBuilder.Append(xrefInUseBlockBuilder);
// Initialize next block!
xrefInUseBlockBuilder.Length = 0;
freeReference = indirectObject.Reference;
}
}
// Add last free entry!
AppendXRefEntry(xrefBuilder, freeReference, 0);
// End last block!
xrefBuilder.Append(xrefInUseBlockBuilder);
}
// 3. XRef table (unique section) [PDF:1.6:3.4.3].
long startxref = stream.Length;
stream.Write(xrefBuilder.ToString());
// 4. Trailer [PDF:1.6:3.4.4].
WriteTrailer(startxref, xrefSize, null);
}
/**
* <summary>Adds an indirect object entry to the specified xref stream.</summary>
* <param name="xrefEntry">Indirect object's xref entry.</param>
* <param name="indirectObject">Indirect object.</param>
* <param name="xrefStream">XRef stream.</param>
* <param name="prevFreeEntry">Previous free xref entry.</param>
* <returns>Current free xref entry.</returns>
*/
private XRefEntry AddXRefEntry(
XRefEntry xrefEntry,
PdfIndirectObject indirectObject,
XRefStream xrefStream,
XRefEntry prevFreeEntry
)
{
xrefStream[xrefEntry.Number] = xrefEntry;
switch (xrefEntry.Usage)
{
case XRefEntry.UsageEnum.InUse:
// Set entry content's offset!
xrefEntry.Offset = (int)stream.Length;
// Add entry content!
indirectObject.WriteTo(stream);
break;
case XRefEntry.UsageEnum.InUseCompressed:
/* NOOP: Serialization is delegated to the containing object stream. */
break;
case XRefEntry.UsageEnum.Free:
if (prevFreeEntry != null)
{
prevFreeEntry.Offset = xrefEntry.Number;
} // Object number of the next free object.
prevFreeEntry = xrefEntry;
break;
default:
throw new NotSupportedException();
}
return(prevFreeEntry);
}
/**
* <summary>Adds an indirect object entry to the specified xref stream.</summary>
* <param name="xrefEntry">Indirect object's xref entry.</param>
* <param name="indirectObject">Indirect object.</param>
* <param name="xrefStream">XRef stream.</param>
* <param name="prevFreeEntry">Previous free xref entry.</param>
* <param name="extensionObjectStreams">Object streams used in incremental updates to extend
* modified ones.</param>
* <returns>Current free xref entry.</returns>
*/
private XRefEntry AddXRefEntry(
XRefEntry xrefEntry,
PdfIndirectObject indirectObject,
XRefStream xrefStream,
XRefEntry prevFreeEntry,
IDictionary <int, ObjectStream> extensionObjectStreams
)
{
xrefStream[xrefEntry.Number] = xrefEntry;
switch (xrefEntry.Usage)
{
case XRefEntry.UsageEnum.InUse:
{
int offset = (int)stream.Length;
// Add entry content!
indirectObject.WriteTo(stream, file);
// Set entry content's offset!
xrefEntry.Offset = offset;
}
break;
case XRefEntry.UsageEnum.InUseCompressed:
/*
* NOTE: Serialization is delegated to the containing object stream.
*/
if (extensionObjectStreams != null) // Incremental update.
{
int baseStreamNumber = xrefEntry.StreamNumber;
PdfIndirectObject baseStreamIndirectObject = file.IndirectObjects[baseStreamNumber];
if (baseStreamIndirectObject.IsOriginal()) // Extension stream needed in order to preserve the original object stream.
{
// Get the extension object stream associated to the original object stream!
ObjectStream extensionObjectStream;
if (!extensionObjectStreams.TryGetValue(baseStreamNumber, out extensionObjectStream))
{
file.Register(extensionObjectStream = new ObjectStream());
// Link the extension to the base object stream!
extensionObjectStream.BaseStream = (ObjectStream)baseStreamIndirectObject.DataObject;
extensionObjectStreams[baseStreamNumber] = extensionObjectStream;
}
// Insert the data object into the extension object stream!
extensionObjectStream[xrefEntry.Number] = indirectObject.DataObject;
// Update the data object's xref entry!
xrefEntry.StreamNumber = extensionObjectStream.Reference.ObjectNumber;
xrefEntry.Offset = XRefEntry.UndefinedOffset; // Internal object index unknown (to set on object stream serialization -- see ObjectStream).
}
}
break;
case XRefEntry.UsageEnum.Free:
if (prevFreeEntry != null)
{
prevFreeEntry.Offset = xrefEntry.Number;
} // Object number of the next free object.
prevFreeEntry = xrefEntry;
break;
default:
throw new NotSupportedException();
}
return(prevFreeEntry);
}