Show HN: PDF Debugger – Inspect Structure of PDF Files

That's very cool!

1. Is the source available anywhere? I'm curious to see how it works.

2. Is there a way to connect the structure displayed here, to the rendered version in the PDF? To visually display the subcomponents?

Regarding 2.: Most of these objects do not directly correspond to rendered elements. Basically every page has one (typically) content stream which will contain all rendered elements. The biggest rendered thing you see outside of that are annotations (link boxes, form fields, actual annotations, ...).

It's a bit different if you are looking at a tagged PDF, where the tagging structure is in there, but if you want to look at that in detail you are probably better served with e.g. ngPDF (https://ngpdf.com/) which will show the tagging structure including the mapping to rendered elements.

Thanks! I've fixed the typo and also allowed the selection of the node's text on the left panel (it was disabled by default).

I haven't decided if I want to create an open-source version. In the first place, I made it private to worry less about my code quality and to finish the product faster before I lose interest in it.

It heavily relies on the core part of PDF.js: I've made a fork of the PDF.js project, removed everything not related to the core part, and added an export for low-level primitives [1].

Also, as inspiration, I used the pdf.js.utils [2] project, which almost does the same but in a different form.

1. https://github.com/hyzyla/pdf.js-core

2. https://github.com/brendandahl/pdf.js.utils

What's your aim making this here? Is it mostly just to show the sub-components of a PDF? Because if you added more support for Javascript it would fill a need (IDK how niche, lol.)

When I was trying to improve my resume I added some custom Javascript to the PDF using Adobe Reader and what I learned is even Adobe's product makes it painful. Basically the process was something like this:

1. You add a script that loads at certain sections in the document. Let's say this is the equivalent of document.load.

2. To do this there's a field to add the full script which must be typed up correctly beforehand. Only after its added do you know it works and every syntax error requires you to edit your previous script, delete the script you added, and hope your new version works.

3. There's really no interactive way to work with the scripts. Their 'debugger' has almost no features at all or hints of syntax errors. Even getting a script to run in it requires finding the right combination of key strokes in a 1000+ line document on PDF scripting.

The programming itself though is quite simple. It's just Javascript with a different DOM and security model. You can still do event-based programming and write powerful programs - all running inside a PDF. But it will only run in firefox (using PDF.js I think) and Adobe reader (for the JS support.) I just thought I'd tell you that writing these JS programs in PDFs (1) actually seems to have a lot of unrealized potential and (2) the tooling to do so is terrible. So with better JS support it would be useful.