CODEWITHSUNDEEP
node.jspdf
Brandon - Free Palestine
Brandon - Free Palestine

Reputation: 16666

Is it possible to add an image to a PDF without rendering the PDF?

I'm looking at adding an image to an existing PDF in Node.js. None of the PDF libraries I found appear to have the ability to modify an existing PDF though, so I'm planning on implementing it myself. I'm trying to figure out if it's too much work, as I can always do it server side using iTextPDF instead, but I'd prefer to do it in my app (Electron which uses Node.js).

If I just want to modify an existing PDF and add an image, will I have to write a complete rendering library or is PDF structured in such a way that I can write a very small parser that just gets the page I want and inserts an image using the correct format?

Specifically, I'm asking because I've previously looked into writing a text extraction library, put in order to get the position of text you have to render pretty much the entire PDF because of how positioning is handled. That's too much work to get around server side processing in this case.

To be clear, just asking if it's possible to do, not how to do it (don't want to be too broad, I'm sure I can figure that part out).

Upvotes: 1

Views: 426

Answers (1)

dwarring
dwarring

Reputation: 4883

To perform a small manipulation of a PDF, you'll need to implement generalized reading, decompression, encryption and traversal of PDF data structures. Some of the thing you would need to handle include:

  • basic parsing of PDF syntax
  • indexing via the cross reference index, and/or cross reference index and object streams
  • objects (num, byte-string, hex string, dictionary, arrays, booleans...)
  • filters and variants (LZW, Flate, RunLength, Predictors)
  • encryption (RC4, AES, Custom security handlers)
  • page tree traversal
  • basic handling of page content streams
  • image handling
  • serialization, either rewriting of the entire PDF, or incremental updates to an existing PDF

Anything's possible, but realistically, you will need a PDF library or toolkit, client or server-side, to accomplish this.

Upvotes: 1

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