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Strange, I've found pdf.js (the rendering engine Firefox uses) to be one of the most accurate open source viewers, albeit at the cost of loading speed and abili

by franga2000 3y ago

Strange, I've found pdf.js (the rendering engine Firefox uses) to be one of the most accurate open source viewers, albeit at the cost of loading speed and ability to handle massive documents. Are the documents you have issues with generated by some strange industry-specific software per chance? I've seen issues with output from CAD software and some cursed proprietary measurement equipment for chemical labs, but it's been many years since I found an issue with an "everyday" PDF (excluding those interactive JS forms that just yell at you to use Acrobat).

KingOfCoders 3y ago
Firefox 124/Win, Leanpub generated PDF, the Sumatra PDF looks like printed, https://amazingcto.b-cdn.net/FirefoxPDF.png https://amazingcto.b-cdn.net/FirefoxPDF.png
- apetresc 3y ago
  That's very strange, I've never seen the font rendering go so wrong on Windows Firefox. My best guess is that something messed with your font library somewhere, and the browser's engine is picking up a conflicting font with the wrong metrics for glyph width, etc.
  - KingOfCoders 3y ago
    Yes, I wonder though why all other PDF renderers work fine.
- saurik 3y ago
  Can you try disabling (setting to 0) browser.display.use_document_fonts?
  - KingOfCoders 3y ago
    Looks normal again (with set to 0)
    - saurik 3y ago
      This is me shooting from the hip and is probably not useful: do you maybe have a font called "Helvetica" installed on your Windows system? Assuming that guess was wrong (and it almost certainly was): would you mind giving me/us a copy of the PDF file where you experience this? This sounded related to https://bugzilla.mozilla.org/show_bug.cgi?id=1767925 https://bugzilla.mozilla.org/show_bug.cgi?id=1767925 and the workaround people suggest (there and on reddit / launchpad / etc.) while talking about it helped.
      - KingOfCoders 3y ago
        I'll take a look at the bug, the PDF is of an unfinished book I'd rather not give away. No no Helvetica (had to check b/c I had Helvetica for decades on my computers) [Edit] Hmm I have a Win machine and the bug seems to be about Linux?
        saurik 3y ago
        I didn't say you are experiencing the same bug: I said it sounded related; like, having used the workaround from it is teaching us about what aspects of the rendering might be broken. Regardless, if you can give me a PDF file that experiences the issue I would be happy to try to get it fixed, as we shouldn't be sad at Firefox for a bug they aren't fixing if they don't yet have it filed... once it is filed, then we can be sad, as it almost always takes them years to fix anything (if they do at all ;P). FWIW, though, you'd made it sound like this happens to you a lot... if this is really just happening to your PDF of your book generated by some weird website I've never heard of that is generating PDF files with their own code, it is quite possibly a bug in the PDF file and maybe it makes sense to fix Firefox (especially if it really is a font routing bug), but if the PDF file is sufficiently broken there should be some threshold for claiming it is a bug in the file, not the renderer.

KingOfCoders 3y ago

Firefox 124/Win, Leanpub generated PDF, the Sumatra PDF looks like printed, https://amazingcto.b-cdn.net/FirefoxPDF.png https://amazingcto.b-cdn.net/FirefoxPDF.png

apetresc 3y ago
That's very strange, I've never seen the font rendering go so wrong on Windows Firefox. My best guess is that something messed with your font library somewhere, and the browser's engine is picking up a conflicting font with the wrong metrics for glyph width, etc.
- KingOfCoders 3y ago
  Yes, I wonder though why all other PDF renderers work fine.
saurik 3y ago
Can you try disabling (setting to 0) browser.display.use_document_fonts?
- KingOfCoders 3y ago
  Looks normal again (with set to 0)
  - saurik 3y ago
    This is me shooting from the hip and is probably not useful: do you maybe have a font called "Helvetica" installed on your Windows system? Assuming that guess was wrong (and it almost certainly was): would you mind giving me/us a copy of the PDF file where you experience this? This sounded related to https://bugzilla.mozilla.org/show_bug.cgi?id=1767925 https://bugzilla.mozilla.org/show_bug.cgi?id=1767925 and the workaround people suggest (there and on reddit / launchpad / etc.) while talking about it helped.
    - KingOfCoders 3y ago
      I'll take a look at the bug, the PDF is of an unfinished book I'd rather not give away. No no Helvetica (had to check b/c I had Helvetica for decades on my computers) [Edit] Hmm I have a Win machine and the bug seems to be about Linux?
      - saurik 3y ago
        I didn't say you are experiencing the same bug: I said it sounded related; like, having used the workaround from it is teaching us about what aspects of the rendering might be broken. Regardless, if you can give me a PDF file that experiences the issue I would be happy to try to get it fixed, as we shouldn't be sad at Firefox for a bug they aren't fixing if they don't yet have it filed... once it is filed, then we can be sad, as it almost always takes them years to fix anything (if they do at all ;P). FWIW, though, you'd made it sound like this happens to you a lot... if this is really just happening to your PDF of your book generated by some weird website I've never heard of that is generating PDF files with their own code, it is quite possibly a bug in the PDF file and maybe it makes sense to fix Firefox (especially if it really is a font routing bug), but if the PDF file is sufficiently broken there should be some threshold for claiming it is a bug in the file, not the renderer.