Support for modifying existing PDFs?

[heyitsjames]

I don't see a way to modify an existing PDF from the code or examples. Wondering if this is possible. If not, what would it take to add this functionality? Genuinely interested in helping out with this project.

[andrewtimberlake]

It is not currently possible with this library.
To support it would require the ability to read the PDF format, which this library does not support. Once read you would need to be able to modify the PDF data structure and then write it out.
This library only supports a very small subset of the PDF spec and has been built thus far to deal with generating simple documents and invoices I use for my work projects.
To modify PDFs we would need to be able to read and write the entire PDF spec or fail on more complicated documents.