Monospace and other technical book formatting issues

twowheels · 10-05-2020, 12:36 PM

Still evaluating KOReader on my Linux box in preparation for using it on my Kobo, and ran into this interesting problem with the rendering on an ePub of a technical journal. For reference, the journal can be downloaded here: https://accu.org/journals/overload/overload156

Anyhow, I've noticed that monospaced fonts are not shown as monospace (which I've confirmed are displayed as monospace in Calibre's ebook-viewer, and that the css specifies monospace using the highlight & show HTML/CSS feature). I also noticed that some of the overlayed text/images are not rendered correctly.

Is this a known bug, or should I submit a report on gitlab?

twowheels · 10-05-2020, 12:37 PM

... edit: I also noticed that I do not have full-width images turned on, yet they are beings scaled to full width.

twowheels · 10-05-2020, 12:43 PM

I found an option to enable system fonts, which fixed the monospace problem, but not the overlay problem. Will that also carry over to the Kobo install?

NiLuJe · 10-05-2020, 01:47 PM

The answer to "should I open a GH issue?" will pretty much always be "yes"

.

Very few things are actually platform-specific.

In this specific case, KOreader's "system" fonts setting is hidden (and force-enabled) on Kobo (and most other !Desktop platforms). With a caveat: "system" fonts are actually unusable on Kobo (they're obfuscated/encrypted). What is enabled by default are "user" fonts (i.e., what's in /mnt/onboard/fonts), same as Nickel.

That said, we ship Droid Sans Mono, so the "monospace" alias should point to that if nothing else, IIRC.

pazos · 10-05-2020, 03:14 PM

Quote:

Originally Posted by twowheels

... edit: I also noticed that I do not have full-width images turned on, yet they are beings scaled to full width.

Are you sure you didn't touch the document zoom? I cannot reproduce that issue.

twowheels · 10-05-2020, 06:21 PM

Your screenshot doesn't reproduce the image scaling, but does reproduce the more important issue, which is that the numbers are all missing.

twowheels · 10-05-2020, 06:25 PM

...so, I looked at the source for the image and saw that it referenced an svg file, so I unzipped the epub and see that the missing numbers are actually part of the svg, not some trick with overlapping text/image -- so it looks like it's actually a problem with the svg rendering.

EDIT: I've opened the svg in vim and it looks like the svg references an embedded font, "Times New Roman embedded", as well as some embedded glyphs for the 1, 0, ., and + symbols and the various bullets.

EDIT2: And if I browse to the unzipped media folder I see that none of the text in any of the svg files gets rendered.

EDIT3: Looks like it's a known limitation of nanosvg.

pazos · 10-05-2020, 06:57 PM

Quote:

Originally Posted by twowheels

Your screenshot doesn't reproduce the image scaling, but does reproduce the more important issue, which is that the numbers are all missing.

Having all issues mixed together doesn't work well. I was addressing the issue you mentioned on the quote. Which I couldn't repro.

About the other issue, see next post

pazos · 10-05-2020, 06:59 PM

Quote:

Originally Posted by twowheels

...so, I looked at the source for the image and saw that it referenced an svg file, so I unzipped the epub and see that the missing numbers are actually part of the svg, not some trick with overlapping text/image -- so it looks like it's actually a problem with the svg rendering.

EDIT: I've opened the svg in vim and it looks like the svg references an embedded font, "Times New Roman embedded", as well as some embedded glyphs for the 1, 0, ., and + symbols and the various bullets.

EDIT2: And if I browse to the unzipped media folder I see that none of the text in any of the svg files gets rendered.

Yup. Nanosvg doesn't support embedded text. See https://github.com/koreader/koreader...ment-703837152

Ken Maltby · 10-06-2020, 12:50 AM

Do we still have the ability to open a file using the other reader? Just a thought.

Frenzie · 10-07-2020, 04:40 PM

You mean long-press in the file manager and choose open with MuPDF? Could be worth a shot, it has SVG support too. But right now we're still on MuPDF 1.13, while 2020.11 will likely be upgraded to 1.17 thanks to @ezdiy's efforts. You can check that rendering independently from KOReader too.

10-05-2020, 12:36 PM	#1
twowheels Wizard Posts: 1,786 Karma: 13412766 Join Date: Nov 2010 Device: Kobo Clara HD, iPad Pro 10", iPhone 15 Pro	Monospace and other technical book formatting issues Still evaluating KOReader on my Linux box in preparation for using it on my Kobo, and ran into this interesting problem with the rendering on an ePub of a technical journal. For reference, the journal can be downloaded here: https://accu.org/journals/overload/overload156 Anyhow, I've noticed that monospaced fonts are not shown as monospace (which I've confirmed are displayed as monospace in Calibre's ebook-viewer, and that the css specifies monospace using the highlight & show HTML/CSS feature). I also noticed that some of the overlayed text/images are not rendered correctly. Is this a known bug, or should I submit a report on gitlab? Attached Thumbnails

10-05-2020, 06:25 PM	#7
twowheels Wizard Posts: 1,786 Karma: 13412766 Join Date: Nov 2010 Device: Kobo Clara HD, iPad Pro 10", iPhone 15 Pro	...so, I looked at the source for the image and saw that it referenced an svg file, so I unzipped the epub and see that the missing numbers are actually part of the svg, not some trick with overlapping text/image -- so it looks like it's actually a problem with the svg rendering. EDIT: I've opened the svg in vim and it looks like the svg references an embedded font, "Times New Roman embedded", as well as some embedded glyphs for the 1, 0, ., and + symbols and the various bullets. EDIT2: And if I browse to the unzipped media folder I see that none of the text in any of the svg files gets rendered. EDIT3: Looks like it's a known limitation of nanosvg. Last edited by twowheels; 10-05-2020 at 06:57 PM.

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10-05-2020, 12:37 PM	#2
twowheels Wizard Posts: 1,786 Karma: 13412766 Join Date: Nov 2010 Device: Kobo Clara HD, iPad Pro 10", iPhone 15 Pro	... edit: I also noticed that I do not have full-width images turned on, yet they are beings scaled to full width.

10-05-2020, 12:43 PM	#3
twowheels Wizard Posts: 1,786 Karma: 13412766 Join Date: Nov 2010 Device: Kobo Clara HD, iPad Pro 10", iPhone 15 Pro	I found an option to enable system fonts, which fixed the monospace problem, but not the overlay problem. Will that also carry over to the Kobo install?

10-05-2020, 01:47 PM	#4
NiLuJe BLAM! Posts: 13,477 Karma: 26012494 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	The answer to "should I open a GH issue?" will pretty much always be "yes" . Very few things are actually platform-specific. In this specific case, KOreader's "system" fonts setting is hidden (and force-enabled) on Kobo (and most other !Desktop platforms). With a caveat: "system" fonts are actually unusable on Kobo (they're obfuscated/encrypted). What is enabled by default are "user" fonts (i.e., what's in /mnt/onboard/fonts), same as Nickel. That said, we ship Droid Sans Mono, so the "monospace" alias should point to that if nothing else, IIRC.

10-05-2020, 06:21 PM	#6
twowheels Wizard Posts: 1,786 Karma: 13412766 Join Date: Nov 2010 Device: Kobo Clara HD, iPad Pro 10", iPhone 15 Pro	Your screenshot doesn't reproduce the image scaling, but does reproduce the more important issue, which is that the numbers are all missing.

10-06-2020, 12:50 AM	#10
Ken Maltby Wizard Posts: 4,465 Karma: 6900052 Join Date: Dec 2009 Location: The Heart of Texas Device: Boox Note2, AuraHD, PDA,	Do we still have the ability to open a file using the other reader? Just a thought.

10-07-2020, 04:40 PM	#11
Frenzie Wizard Posts: 1,615 Karma: 724945 Join Date: Oct 2014 Location: Antwerp Device: Kobo Aura H2O	You mean long-press in the file manager and choose open with MuPDF? Could be worth a shot, it has SVG support too. But right now we're still on MuPDF 1.13, while 2020.11 will likely be upgraded to 1.17 thanks to @ezdiy's efforts. You can check that rendering independently from KOReader too.