[Bug]: Obsidian-exported PDFs have broken text inside highlighted boxes when viewed on Firefox

[NaeemBolchhi]

Attach (recommended) or Link to PDF file

Parallelism-1.pdf

Web browser and its version

Firefox 152.0.6 (Build ID: 20260713164047)

Operating system and its version

Windows 11 24H2

PDF.js version

v6.1.200

Is the bug present in the latest PDF.js version?

Yes

Is a browser extension

No

Steps to reproduce the problem

1. Open the attached PDF in latest firefox build or the online demo of PDF.js
2. See the broken texts inside highlight boxes.

What is the expected behavior?

What went wrong?

Link to a viewer

No response

Additional context

I have been using Obsidian-exported PDFs with such highlight boxes in my classes for more than a year now and have only recently discovered this issue (I use firefox, but my classes use chrome/edge, so I may have been a bit late to pick up on this bug). I think it would be worth testing with the older versions of PDF.js, because I'm sure this used to render properly in firefox before.

[Snuffleupagus]

Mozregression gives the following pushlog https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=cebab6500f0a783295e02fe78f2954ef4a6b009a&tochange=e83a06f0d1809487bf0f406e9361c797a4fa3d3b and setting pdfjs.enableHWA = false in about:config fixes this.

/cc @calixteman

[calixteman]

Mozregression gives the following pushlog https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=cebab6500f0a783295e02fe78f2954ef4a6b009a&tochange=e83a06f0d1809487bf0f406e9361c797a4fa3d3b and setting pdfjs.enableHWA = true in about:config fixes this.

/cc @calixteman

Sorry I'm a bit confused...
the mentioned patch set enableHWA to true so I understand that's causing the issue but then you say that setting it to true fixes the issue.

Anyway I cannot reproduce it myself with 152.0.6 with enableHWA set either to true or false.

[NaeemBolchhi]

Turning pdfjs.enableHWA to false fixes the rendering for me.

Edit 1: Testing with the online demo produces the rendering error regardless of config settings in firefox (probably because its settings are self-contained).

Edit 2: Tried the online demo in Edge. Does not produce this error. So firefox only.

[Snuffleupagus]

Sorry I'm a bit confused...

My bad, that was an unfortunate typo; setting pdfjs.enableHWA = false fixes it for me when testing in Firefox Nightly 155.0a1 on Windows 11.

[calixteman]

@NaeemBolchhi Can you file a bug in bugzilla: https://bugzilla.mozilla.org/enter_bug.cgi?product=Core&component=Graphics%3A%20Canvas2D ?

[NaeemBolchhi]

I have filed a bug report on bugzilla.
https://bugzilla.mozilla.org/show_bug.cgi?id=2056815