Lines split in half in e-book reader - Page 3

KevinH · 10-15-2020, 01:17 PM

There is a github project by Microsoft called Font-Validator. On macOS, the built in Font Book will do font validation. But Linux isprobably your best bet as I remember there being a font editing program that validated the full set of font metrics by walking all of the glyphs in a font. You might google "fontforge" or "birdfont" to see if they validate fonts, especially the font metrics.

You should always validate on borh Windows and Linux/Unix/macOS as there are both Windows and unix spevific font tables.

KevinH · 10-15-2020, 01:22 PM

I think there is a python based font module that does validation if I am remembering correctly.

If the font metrics for height and descenders are not correct you will see a partial line. To make things more difficult there are cases where height includes ascender and decenders and others where they do not.

Just try replacing the font with a known good font, and if theproblem goes away, the issue is with the font (bad or missing font metric data tables).

Hitch · 10-15-2020, 01:57 PM

Quote:

Originally Posted by KevinH

I think there is a python based font module that does validation if I am remembering correctly.

If the font metrics for height and descenders are not correct you will see a partial line. To make things more difficult there are cases where height includes ascender and decenders and others where they do not.

Just try replacing the font with a known good font, and if theproblem goes away, the issue is with the font (bad or missing font metric data tables).

That's why I asked where he obtained that particular Charis SIL. we know that Wolfie uses it all the time; so, if he had a bad version, Wolfie could point him to a known quantity and see if that would fix it. That's kinda how my thinking on this is running, too. Funky Font-ness.

Hitch

JSWolf · 10-15-2020, 07:01 PM

@abecedarian, I suggest you give ChareInk a try. It's based on Charis SIL 5.0 and it has kerning and the bad line height has been fixed.

https://www.mobileread.com/forums/sh...d.php?t=184056

JSWolf · 10-15-2020, 07:02 PM

Quote:

Originally Posted by Hitch

That's why I asked where he obtained that particular Charis SIL. we know that Wolfie uses it all the time; so, if he had a bad version, Wolfie could point him to a known quantity and see if that would fix it. That's kinda how my thinking on this is running, too. Funky Font-ness.

Hitch

I just pointed abecedarian to ChareInk ehich is made from Charis SIL 5.0.

As for Charis SIL, I've never see this issue in any version of the Calibre viewer.

KevinH · 10-15-2020, 10:21 PM

FWIW, All it would take is the line height to be off by 1 pixel in the bad font and that can add up over the page length to end up being half a line. I have seen this problem in other editors. I rarely use calibre so I can not comment on that. I have also seen this problem caused by reported page window sizes being off by half a line even with good fonts.

It looks easy but paginating like calibre's ebook viewer does can be quite difficult to do perfectly. It is not easy.

abecedarian · 10-16-2020, 05:28 AM

Hi guys! I just want to let you know that the help I got from everyone is more than I could ever have anticipated. So thank you

all for the profuse amount of help you are providing on this issue. I'm learning so many new things regarding fonts that I think it will take some time for me to explore and comprehend all the different suggestions that you have been giving. I just need some time to try out all these different proposals. I'll come back as soon as possible. In the mean time I'll keep an eye on this thread.

abecedarian · 11-10-2020, 09:26 PM

I've taken some time to try out some of the suggestions you made. I've narrowed it down to trying JSWolf's ChareInk font. I certainly like this font, the NoWeight version is very close to the original Charis SIL font on my system. It's really very hard to notice any difference. The added weight version is, however, a lot too coarse to my taste. It gives the characters a bold appearance. The ChareInk font seems to completely eliminate the split lines problem when used in epub books that were originally plagued with this unfortunate condition when using the Charis SIL font. I think that generally speaking the Charis SIL font is slightly better in some characters, but the difference is really hard to notice and to complain would be like nitpicking. So from now on I'm going to use the ChareInk NoWeight font whenever the split lines problem occurs in an ebook.

I want to express a heartfelt

to everyone who participated in this thread. I felt real commitment from all participants trying to solve this problem, which was a really good experience. In my opinion this problem has been completely solved, leaving me to say:

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10-15-2020, 01:17 PM	#31
KevinH Sigil Developer Posts: 8,765 Karma: 6000000 Join Date: Nov 2009 Device: many	There is a github project by Microsoft called Font-Validator. On macOS, the built in Font Book will do font validation. But Linux isprobably your best bet as I remember there being a font editing program that validated the full set of font metrics by walking all of the glyphs in a font. You might google "fontforge" or "birdfont" to see if they validate fonts, especially the font metrics. You should always validate on borh Windows and Linux/Unix/macOS as there are both Windows and unix spevific font tables.

10-15-2020, 01:22 PM	#32
KevinH Sigil Developer Posts: 8,765 Karma: 6000000 Join Date: Nov 2009 Device: many	I think there is a python based font module that does validation if I am remembering correctly. If the font metrics for height and descenders are not correct you will see a partial line. To make things more difficult there are cases where height includes ascender and decenders and others where they do not. Just try replacing the font with a known good font, and if theproblem goes away, the issue is with the font (bad or missing font metric data tables).

10-15-2020, 07:01 PM	#34
JSWolf Resident Curmudgeon Posts: 79,758 Karma: 145864619 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	@abecedarian, I suggest you give ChareInk a try. It's based on Charis SIL 5.0 and it has kerning and the bad line height has been fixed. https://www.mobileread.com/forums/sh...d.php?t=184056

10-15-2020, 10:21 PM	#36
KevinH Sigil Developer Posts: 8,765 Karma: 6000000 Join Date: Nov 2009 Device: many	FWIW, All it would take is the line height to be off by 1 pixel in the bad font and that can add up over the page length to end up being half a line. I have seen this problem in other editors. I rarely use calibre so I can not comment on that. I have also seen this problem caused by reported page window sizes being off by half a line even with good fonts. It looks easy but paginating like calibre's ebook viewer does can be quite difficult to do perfectly. It is not easy.

10-16-2020, 05:28 AM	#37
abecedarian Enthusiast Posts: 27 Karma: 10 Join Date: Dec 2016 Location: Groningen, Netherlands Device: Calibre, Kobo Aura H2O	Hi guys! I just want to let you know that the help I got from everyone is more than I could ever have anticipated. So thank you all for the profuse amount of help you are providing on this issue. I'm learning so many new things regarding fonts that I think it will take some time for me to explore and comprehend all the different suggestions that you have been giving. I just need some time to try out all these different proposals. I'll come back as soon as possible. In the mean time I'll keep an eye on this thread.

11-10-2020, 09:26 PM	#38
abecedarian Enthusiast Posts: 27 Karma: 10 Join Date: Dec 2016 Location: Groningen, Netherlands Device: Calibre, Kobo Aura H2O	I've taken some time to try out some of the suggestions you made. I've narrowed it down to trying JSWolf's ChareInk font. I certainly like this font, the NoWeight version is very close to the original Charis SIL font on my system. It's really very hard to notice any difference. The added weight version is, however, a lot too coarse to my taste. It gives the characters a bold appearance. The ChareInk font seems to completely eliminate the split lines problem when used in epub books that were originally plagued with this unfortunate condition when using the Charis SIL font. I think that generally speaking the Charis SIL font is slightly better in some characters, but the difference is really hard to notice and to complain would be like nitpicking. So from now on I'm going to use the ChareInk NoWeight font whenever the split lines problem occurs in an ebook. I want to express a heartfelt to everyone who participated in this thread. I felt real commitment from all participants trying to solve this problem, which was a really good experience. In my opinion this problem has been completely solved, leaving me to say: