Possible Xournal++ integration

[kommeleon]

Hi,

I'm currently on the search for the ideal PDF annotation tool. For now, I've gotten used to Xournal++, which in my opinion, is the best open-source tool to annotate PDFs. Recently though, I've gotten a bit annoyed at the lack of any kind of note hierarchy or any kind of organization features for my notes. The only thing you can do is put different classes (e.g. Math, English, etc.) in different folders, but changing from one note to another still isn't nearly as easy as something like OneNote or Trilium.

Every single one of my classes depends on being able to annotate PDFs and not being able to use such a powerful tool like Trilium and Xournal++ in conjunction really seems like a missed opportunity to me. I've already tried out Trilium and have self-hosted an instance and I really like the application, but without PDF annotation, I won't be able to use it in my classes. A friend of mine recently switched to Linux and he even decided to run a Virtual Machine on his Laptop, just to have a hierarchical PDF annotation tool with easy synchronization, OneNote.

Maybe this could be a plugin or a new note type of some sort? The way that Xournal++ stores its files is that it doesn't change the PDF background and only saves a .xopp file with the annotations, making it so that the note only works if you have both the PDF background and the .xopp file. I was thinking that you could maybe put a PDF into Trilium, then press a Xournal++ button or widget, it then opens Xournal++ via a command line command outside of Trilium and when you close the Xournal++ window, it saves the .xopp file in Trilium alongside the PDF background and you also (via the integrated Xournal++ command) export the annotated PDF (the PDF background + the .xopp annotations) to a PDF, so that it can be easily shown in the Trilium interface. The reason you don't just use the annotated PDF is because you aren't able to edit any of your annotations on a PDF after it has been exported.
To recap, Trilium would save your PDF + your annotations in .xopp format + a PDF file that has both the PDF background and your annotations, all in three separate files in one note.

This seems overly complicated, but right now, I think it's the only way you'd be able to open your annotated PDFs on any type of device and annotate them on devices with Xournal++.

There is an open-source Obsidian Plugin called [obsidian-xournalpp] which allows you to do this on Obsidian. But right now, it doesn't support annotating PDFs on multiple different devices as it is mainly made to create a .xopp file, with no PDF background and it then exports the annotated .xopp file to a PDF so that it can be shown inside of Obsidian. Sadly, that isn't my desired use case and I'd much rather self-host an open-source application, like Trilium. But maybe this could be used to see how it'd be implemented?

I don't have much experience with code in general and don't really know how feasible this is, but I would greatly appreciate any kind of integration with Xournal++ to add PDF annotation, whether integrated officially into Trilium or added via a separate script.

Thanks in advance for the response.