PDF math equations are displayed incorrectly

[proudzhu]

Search first

• I searched and no similar issues were found

What Happened?

PDF math equations are displayed incorrectly

Reproduce the Bug

Just open the attached pdf.
Sohn 等 - 1999 - A statistical model-based voice activity detection.pdf

Expected Behavior

No response

Screenshots

open from logseq

open in zotero

Desktop or Mobile Platform Information

Win11, logseq 0.8.15

Additional Context

No response

Are you willing to submit a PR?

• I'm willing to submit a PR (Thank you!)

[andrewcrook]

I noticed a couple of things

• I get the same on macOS with that file,
• however, it does work using Mozilla’s PDF.js (which LogSeq also uses) built into Firefox. Maybe it needs to be updated in logseq?
• Under logseq I see the console error
  Warning: fetchStandardFontData: failed to fetch file "FoxitSymbol.pfb" with "UnknownErrorException: StandardFontDataFactory not initialized, see the “useWorkerFetch" parameter.”.
• Apparently Mozilla PDF.js is not complete when it comes to Foxitfont support. As mentioned
  Replace most Foxit fonts with Liberation fonts mozilla/pdf.js#14843
• I also wonder if it's something to do with useWorkerFetch ?

Also, note that both useWorkerFetch and cMapUrl are parameters that you need to pass to getDocument

• StandardFontDataFactory not initialized with Vite Vue3 in renderTextLayer mozilla/pdf.js#15551 (comment)
• I also noticed that the PDF file uses Type 3 fonts these haven't been used for a long time and I have had troubles with them in some PDF tools namely Ghostscript. Although type 3 fonts are bitmap some glyphs can be defined as any arbitrary PostScript. nor do they support hinting when scaling and zooming small. Overall support is thin in apps and OSs.

[andrewcrook]

• In the meantime, I wonder if using a PDF tool/editor to change fonts and embed them into the PDF might work?
• maybe favour some OpenType fonts (which is packaging) which show as Type 1 when embedded (type 2 compression in OTF uncompressed when embedded). I think I have that correct
• Adobe is dropping support for Type1 in favour of concentrating on the use of the more versatile OTF
  https://helpx.adobe.com/uk/fonts/kb/postscript-type-1-fonts-end-of-support.html

FYI

>>pdffonts ./Downloads/Sohn.-.1999.-.A.statistical.model-based.voice.activity.detection.pdf 
name                                 type              encoding         emb sub uni object ID
------------------------------------ ----------------- ---------------- --- --- --- ---------
Times-Italic                         Type 1            Custom           no  no  no      30  0
Times-Roman                          Type 1            Custom           no  no  no      29  0
Symbol                               Type 1            Symbol           no  no  no      45  0
Times-Bold                           Type 1            Custom           no  no  no      32  0
Times-BoldItalic                     Type 1            Custom           no  no  no      33  0
[none]                               Type 3            Custom           yes no  no      16  0
[none]                               Type 3            Custom           yes no  no      10  0

anyway I hope this information helps someone to fix the issue in LogSeq
and for other to think about how they should be creating PDFs from now on and/or avoid bit rot when archiving.

[github-actions]

Hi There! 👋

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[sujjeee]

hey @andrewcrook something similar issue any idea how i can fix this ??
Warning: fetchStandardFontData: failed to fetch file "LiberationSans-Bold.ttf" with "UnknownErrorException: The standard font "baseUrl" parameter must be specified, ensure that the "standardFontDataUrl" API parameter is provided.".

[andrewcrook]

@sujjeee No sorry I am no longer using Logseq because I wanted to have a page system like obsidian.
Its an issue with PDFJS I believe there are some things that can be done.

Other than that, I would check with other editors/readers if fonts are type 1, installed on the system or are embedded in the PDF and maybe play around with the PDF embedding or change fonts etc to see if it makes a difference.

can you link to the PDF so I can have a look?