Letter alignment of diagonal text regressed in Firefox 47 on Linux

[fkaelberer]

PDF file:
https://web.archive.org/web/20160328235633/http://www.bvg.de/images/content/linienverlaeufe/LinienverlaufBus101.pdf

Affected Configurations:

• Firefox 48.0a1 (2016-04-01) + Linux Mint 17.3 (screenshot, right)
• Firefox 48.0b9 + Linux Mint 17.3
• Firefox 46.0.1 + Android 6.0.1
• Firefox 47.0b6 + Android 6.0.1
• Firefox 48.0b6 + Android 6.0.1
• HWA off & on

Not Affected:

• Firefox 46.0 + Linux Mint 17.3 (screenshot, left)
• Firefox 47.0 + Linux Mint 17.3
• Firefox 50.0a1 (2016-07-11) + Linux Mint 17.3
• Google Chrome
• Firefox 46-49 + Windows

PDF.js version: 1.5.264
Is an extension: No

What went wrong?

The image shows the pdf file in the demo viewer on Firefox 46 (left) and Firefox 48 (right). On the right side, letters are not aligned.

[timvandermeij]

This is related to #7277 where we first spotted this. As far as I know this has not yet been reported upsteam. Could someone take care of that who knows where the right place is to report this issue?

[fkaelberer]

I noticed that it's broken in Firefox 46 on Android already, and updated the initial comment accordingly.

[timvandermeij]

@fkaelberer Does this still happen? It seems fixed for my using Firefox 47.0.1 on Arch Linux and the bots also don't have this problem anymore, so I think upstream uplifted a patch for this.

[fkaelberer]

Still broken with pdf.js 1.5.343 / Firefox 48.0b6. Edit: on Android.

I just tested Linux Mint and the issue does appear in Firefox 48b9 but not on Firefox 47.0 or 50.0a1 (2016-07-11).

[Snuffleupagus]

@fkaelberer Based on your "Not Affected:" list above, it seems that this has been fixed upstream.
Would you be able to use mozregression, see http://mozilla.github.io/mozregression/, to find out when and in which commit/bug this was fixed?

[fkaelberer]

@Snuffleupagus Awesome tool ;-)
Broke in https://hg.mozilla.org/integration/mozilla-inbound/rev/180f3f0494a7
Fixed in https://hg.mozilla.org/integration/mozilla-inbound/rev/2a0eda9a4bb6

[timvandermeij]

Thank you for looking into that! Based on these findings I'm closing this issue as fixed, also since it's not something we can address in PDF.js as it's really a browser bug.

[Snuffleupagus]

[...] also since it's not something we can address in PDF.js as it's really a browser bug.

What could perhaps be done is to comment in https://bugzilla.mozilla.org/show_bug.cgi?id=1274111, referring to e.g. this issue and pointing out that it's affecting the PDF viewer in Firefox on Linux, and ask if the patch could be uplifted to Firefox 48.
At this point, we're getting close to the next Firefox release, but I suppose it can't hurt to ask!

[timvandermeij]

Sounds good. It might prevent issues for the next release(s).