Adobe acrobat (and maybe reader) is really the only app that fully supports the full PDF spec as understood by the authors of the spec. There are ridiculous parts of the spec that allow support for things like JS, etc.
> Adobe acrobat (and maybe reader) is really the only app that fully supports the full PDF spec
The full spec is large and afaik has many obscure pieces, including 3-D, etc. Like many specs, they don't match reality and nobody takes completeness too seriously. For almost all users, supporting the entire PDF spec doesn't matter (does it matter for any user - does any person or organization use the entire spec over their lifetimes?).
Also, do we know that Adobe supports the entire spec?
There's a fairly big chunk in the spec of special presentation attributes for slideshows. When I implemented them I was surprised that slide shows produced by Acrobat didn't work. Well, obviously my implementation was buggy.
Er, no, Adobe didn't use their own slide show attributes for the slide shows produced by Acrobat. They used JavaScript instead.
Oh well. ¯\_(ツ)_/¯
Adobe Acrobat is the only thing that can handle all cases yes. All other programs uses (different) special cases each and most of them fail in some edge cases. It can be funny letters showing up because of fonts not working properly or images disapearing or all sorts of things. I have given up to fix them all. I still have a library of PDF's that we used to run through to try to get as many as possible to work.
That's because PDF is well designed and has a fallback for advanced page elements so more primitive readers can still render them.
https://pdfa.org/resource/pdf-in-manufacturing/ is a great usecase.
I recently had to add an embed feature to our pdf rendering, to allow users to embed other pdfs inside the one we generate for them. Since we use headless Chrome, I used pdfjs from mozilla to render the embedded pdf on screen before generating the pdf, so you can actually see and read the embedded pdf.
Works pretty well, but was wondering about this attachment feature of pdfs.
Since these pdfs end up in whatever and how old devices, I'd rather not risk it though.