Tablet stuck loading when opening PDFs on PdfReaderScreen

[Dima-Android]

Several users have reported that since sometime in December the app has started showing infinite loading on PdfReaderScreen when opening some, or even all PDFs in user’s library.
Users also report freezing using jumping to page functionality by tapping on page previews at the bottom.
https://forums.zotero.org/discussion/129004/debug-id-d1702057388-d1090846459-d1017421858/p1
https://forums.zotero.org/discussion/128712/zotero-on-xiaomi-pad-7-spinning-circle-issue-with-large-pdfs
https://forums.zotero.org/discussion/129003/ereader-in-zotero-app-on-android-no-longer-working/p1
https://forums.zotero.org/discussion/128969/android-zotero-tablet-stuck-loading/p1

All reported users use tablets, in one case running Android 13 and Android 16 in other.

Here are my thoughts as of now:
The spinner shown there is not ours, it’s nutrient’s, the spinner is shown when nutrient’s PDF reader was fed the PDF and it started loading it. Why it’s not able to finish loading it is unknown. Although in some cases user report that it does finish loading it, but it takes a lot of time.
Unable to reproduce this issue on any of my own testing files on both phone and tablet. I was testing with file sizes up until 20 megs, maybe should try with bigger ons.

Time-wise the appearance of those issues align with us pushing a new build with lots of dependencies updated including the major version upgrade of nutrient (where nutrient implemented the performance optimisations)

[Dima-Android]

Just upgraded nutrient from version 10.5.0 to 1.10.1 which brings these improvements that should hopefully help with this issue at least partially:

Improves the responsiveness of the document editor when dealing with large documents. (J#ANDR-1587)

Fixes deadlocks that could occur when rendering documents with more than 100 pages. (J#IOS-830)

Fixes an ANR that could occur during page initialization with heavy documents. (J#ANDR-1521)

[Dima-Android]

i was finally able to reproduce the bug stylus-related unresponsiveness. User mentioned that even just using a finger will make the PDFScreen unresponsive, so I tried doing that in bunch of PDF modes and various files but couldn’t make it freeze.
But I’ve found if you just touch the screen with stylus, regardless if you are in annotation editing mode or not, it makes the view, in which nutrient displays PDF completely unresponsive for all interactions. The top bar and sidebar (which are ours) are still interact-able though.
After about 10 seconds, if you were to interact with PDF with fingers it starts to work. But then if you touch it with stylus it becomes unresponsive again.
It’s not that the app freezes nor nutrient part freezes, as tapping Undo-Redo still works, it’s just events are not propagated.

I’ve downloaded Nutrient’s sample app and there it just works! Both for stylus and for finger, so I was trying to debug our app and figure out what are we doing wrong, but couldn’t figure it out. Nutrient just stops sending us all touch events after stylus is involved.
Also just downgrading from 10.10.1 to 10.5.0 makes stylus work again.
But then if we do that then we still have bug with very long or infinite spinner for large PDFs.
So I downgraded to even earlier version where we had none of those issues.
It will also help us to figure out whether those bugs has anything to do with modifications to PdfScreen’s logic we did recently

I’ve also noticed in last 5 version upgrade’s changelogs nutrient keep mentioning the fix or improvement for stylus eraser, so maybe they are still stabilising it and it spills into general stylus interactions. So let’s give it some time too.