itext7 barcodes in footer - barcode

Question

I'm working on a rather complex solution that takes an html-like input and converts it to a pdf. One of the many items that I'm trying to solve for is adding barcodes (all types, 3 of 9, PDF417, and qr code) to the footer of documents.
A couple details that give me pause on how to implement:
Bar code will contain current page number
Bar code will contain total page count
Bar code will be inside other itext elements (like a table cell or paragraph) and (in the final solution) needs to be parsed out ahead of time
Knowing those details, I'm struggling a bit on how to combine barcodes with something like the page x of y strategy of using a template to replace page count after rendering all the content.
I assume that each bar code will need it's own template because of the page count, and keep track of the templates until all the content is rendered and then update each individual template with the appropriate bar code. But because the footer is parsed out ahead of time, I need a template that represents a bar code so that the footer will have the correct height and content can be adjusted appropriately.
I believe that each of these pieces need to be handled in the event handler for end of page, is that a correct assessment?
UPD Edited to include code sample. I pulled out quite a bit of the other stuff I was trying to accomplish from this example. As for the parsed ahead of time, instead of going over a loop from 1 to 20 and creating random elements, some other process creates all the elements that need to be present on the document and will pass in that list of elements to the renderer. That does include the footer content as well. In this case I'm creating the footer table in the constructor of the HeaderHandler as that is close to the same concept. The reason I bring this up is that I won't be able to create the table in the HandleEvent of the handler like in most examples I have seen about tables in footers. Hope that makes sense.
void Main()
{
PdfDocument pdf = new PdfDocument(new PdfWriter(Dest));
PageSize pageSize = PageSize.A4;
Document doc = new Document(pdf, pageSize, true);
HeaderHandler hh = new HeaderHandler(doc);
...
some other object generation
...
// create random paragraphs to fill up multiple pages in the final solution this would have already happened.
for (var i = 0; i < 20; i++)
AddItemToList(elementList, i, objects);
// add random elements back to the document
foreach (var e in elementList)
{
... add each item just added to elementList to the document ...
}
renderer.Flush();
hh.UpdateTotal(pdf);
// I think I need to update all the barcodes and print them out here so that page count part of the barcode can be written
doc.Close();
}
class HeaderHandler : IEventHandler
{
Table Footer;
Document Doc;
public Margin First;
public Margin Middle;
public Margin Last;
public Dictionary<int, Margin> PageMargins { get; set; }
public float HeaderHeight { get; }
public float FooterHeight { get; }
PdfFormXObject PgCount;
Text PageNumber;
Dictionary<string, PdfFormXObject> BarcodeImages;
public HeaderHandler(Document doc)
{
Doc = doc;
Footer = new Table(new float[] { 4, 2, 4}).SetAutoLayout();
PageMargins = new Dictionary<int, Margin>();
BarcodeImages = new Dictionary<string, PdfFormXObject>();
var pageSize = Doc.GetPdfDocument().GetDefaultPageSize();
var width = pageSize.GetRight() - pageSize.GetLeft() - Doc.GetLeftMargin() - Doc.GetRightMargin();
// page total
PgCount = new PdfFormXObject(new Rectangle(0,0, 13, 13));
Footer.AddCell(new Cell().Add(new Paragraph("info 1")));
PageNumber = new Text("{page}");
var cell = new Cell().Add(new Paragraph().Add(PageNumber).Add(" of ").Add(new Image(PgCount)).Add(" pages").SetTextAlignment(TextAlignment.CENTER));
Footer.AddCell(cell);
Footer.AddCell(new Cell().Add(new Paragraph("info 2")));
Footer.AddCell("footer 1");
Footer.AddCell("footer 2");
// I think I need to add a template here for the barcode as a placeholder so that when the renderersubtree is ran it provides space for the barcode
Footer.AddCell(new Cell().Add(new Paragraph("{barcode} {qr code - {page} | {pagect} | doc name}")));
TableRenderer fRenderer = (TableRenderer)Footer.CreateRendererSubTree();
using (var s = new MemoryStream())
{
fRenderer.SetParent(new Document(new PdfDocument(new PdfWriter(s))).GetRenderer());
FooterHeight = fRenderer.Layout(new LayoutContext(new LayoutArea(0, PageSize.A4))).GetOccupiedArea().GetBBox().GetHeight();
}
}
public void UpdateTotal(PdfDocument pdf) {
Canvas canvas = new Canvas(PgCount, pdf);
canvas.ShowTextAligned(pdf.GetNumberOfPages().ToString(), 0, -3, TextAlignment.LEFT);
}
//draw footer and header tables
public void HandleEvent(Event e)
{
PdfDocumentEvent docEvent = e as PdfDocumentEvent;
if (docEvent == null)
return;
PdfDocument pdf = docEvent.GetDocument();
PdfPage page = docEvent.GetPage();
PdfCanvas pdfCanvas = new PdfCanvas(page.GetLastContentStream(), page.GetResources(), pdf);
int pageNum = pdf.GetPageNumber(page);
var pageSize = Doc.GetPdfDocument().GetDefaultPageSize();
Margin activeMargin = new Margin();
if (PageMargins.ContainsKey(pageNum))
activeMargin = PageMargins[pageNum];
var width = pageSize.GetRight() - pageSize.GetLeft() - activeMargin.Left - activeMargin.Right;
Header.SetWidth(width);
Footer.SetWidth(width);
var pageReferences = new List<TextRenderer>();
// update page number text so it can be written to in the footer
PageNumber.SetText(pageNum.ToString());
// draw the footer
rect = new Rectangle(pdf.GetDefaultPageSize().GetX() + activeMargin.Left, activeMargin.Bottom - GetFooterHeight(), 100, GetFooterHeight());
canvas = new Canvas(pdfCanvas, pdf, rect);
// I think it's here that I need to be able to add a barcode placeholder to something that can be called
canvas.Add(Footer);
}
public float GetFooterHeight()
{
return FooterHeight;
}
}