/**
<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;
}
