Cool Reader and kerning

IceHand · 02-15-2015, 01:19 PM

Recently I installed the newest Cool Reader for my Kindle 3 from CrazyCoder's Github. It's working fine, but I can't get kerning to work. The checkbox in the options menu does nothing.

I checked the desktop version on my Linux PC and there I can't even find a kerning checkbox. Kerning doesn't work here either.

And yes, I've tried with fonts that have kerning information. When I try FBReader on my Linux PC the kerning with the same fonts looks fine. Unfortunately I can't seem to find a working download for FBReader for Kindle 3.

Am I missing something or does Cool Reader not support kerning? Any other way to get decent kerning on my Kindle 3 or any other more recent e-ink device (I might upgrade if I got better font handling)?

NiLuJe · 02-15-2015, 03:56 PM

@IceHand: IIRC, because this came up w/ KOReader when I looked into it, the kerning mentioned is only FreeType's very, very, very basic kerning support, which is (according both to FT's docs and my testing) fairly useless. Kerning's the job of a layout engine (w/ a FT/FC stack, usually harfbuzz, or something using harfbuzz [cairo+pango/Qt]), something that's mostly nonexistent with CRe.

TL;DR: Nope.

IceHand · 02-16-2015, 05:47 AM

Hm, I feared as much. Do you know any recent e-ink reader where it's possible to get proper kerning and hyphenation? I could use XeTeX to get a good looking PDF, but that's an awful lot of work.

bhaak · 02-17-2015, 03:51 AM

Quote:

Originally Posted by NiLuJe

@IceHand: IIRC, because this came up w/ KOReader when I looked into it, the kerning mentioned is only FreeType's very, very, very basic kerning support, which is (according both to FT's docs and my testing) fairly useless. Kerning's the job of a layout engine (w/ a FT/FC stack, usually harfbuzz, or something using harfbuzz [cairo+pango/Qt]), something that's mostly nonexistent with CRe.

TL;DR: Nope.

If you look at this screenshot of HackedUpReader (which as I understand is using the same crengine code as KOReader), you see that basic kerning on a KT is working okay (check for "Tochter" or "Tau" in the middle of the screen):
http://bhaak.net/kindle/hackedupreader_blindtext.png

But this is not with the builtin freetype library but the one we compiled separately for the K5 devices. The builtin is missing LOTS of features, including any kerning support (if you look closely, you'll notice that the Amazon fonts are designed to look good with no kerning, so they know about it).

I don't know if the K3 can use the same freetype library and I agree that the crengine code is not a full layout engine.

But for a alphabetic left-to-right language, it is better than the Amazon engine (which does nothing) and far from useless.

NiLuJe · 02-17-2015, 08:03 AM

@bhaak: It's very, very subtle, and works on a small subset of fonts (old kern tables, no GPOS support, IIRC). But, yeah, if enabled (which I think I did by default), that should also be handled w/ KOReader.

sadowski · 02-17-2015, 08:26 AM

I found that (for at least some fonts like charis sil) kerning in coolreader actually reduces the quality of the font rendering. So I keep it off. No idea why that is.

IceHand · 02-18-2015, 08:34 AM

I don't understand why FBReader isn't more popular. At least the desktop version that I tested on my Linux PC offers far superior font rendering with true kerning and even automatic ligatures.

@bhaak: Well, freetype's kerning might be better than nothing, but it's far from ideal. I might take a look at HackedUpReader though, if I get a newer Kindle.

@sadowski: Huh, that's weird. Even more so because Charis SIL has no kerning information included.

02-15-2015, 01:19 PM	#1
IceHand Linux User Posts: 323 Karma: 13682 Join Date: Aug 2007 Location: Germany Device: Kindle 3	Cool Reader and kerning Recently I installed the newest Cool Reader for my Kindle 3 from CrazyCoder's Github. It's working fine, but I can't get kerning to work. The checkbox in the options menu does nothing. I checked the desktop version on my Linux PC and there I can't even find a kerning checkbox. Kerning doesn't work here either. And yes, I've tried with fonts that have kerning information. When I try FBReader on my Linux PC the kerning with the same fonts looks fine. Unfortunately I can't seem to find a working download for FBReader for Kindle 3. Am I missing something or does Cool Reader not support kerning? Any other way to get decent kerning on my Kindle 3 or any other more recent e-ink device (I might upgrade if I got better font handling)?

02-15-2015, 03:56 PM	#2
NiLuJe BLAM! Posts: 13,477 Karma: 26012492 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	@IceHand: IIRC, because this came up w/ KOReader when I looked into it, the kerning mentioned is only FreeType's very, very, very basic kerning support, which is (according both to FT's docs and my testing) fairly useless. Kerning's the job of a layout engine (w/ a FT/FC stack, usually harfbuzz, or something using harfbuzz [cairo+pango/Qt]), something that's mostly nonexistent with CRe. TL;DR: Nope. Last edited by NiLuJe; 02-15-2015 at 03:58 PM.

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02-16-2015, 05:47 AM	#3
IceHand Linux User Posts: 323 Karma: 13682 Join Date: Aug 2007 Location: Germany Device: Kindle 3	Hm, I feared as much. Do you know any recent e-ink reader where it's possible to get proper kerning and hyphenation? I could use XeTeX to get a good looking PDF, but that's an awful lot of work.

02-17-2015, 08:03 AM	#5
NiLuJe BLAM! Posts: 13,477 Karma: 26012492 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	@bhaak: It's very, very subtle, and works on a small subset of fonts (old kern tables, no GPOS support, IIRC). But, yeah, if enabled (which I think I did by default), that should also be handled w/ KOReader.

02-17-2015, 08:26 AM	#6
sadowski Connoisseur Posts: 84 Karma: 1142796 Join Date: Jul 2009 Device: Sony PRS 350, Kobo mini, PB mini	I found that (for at least some fonts like charis sil) kerning in coolreader actually reduces the quality of the font rendering. So I keep it off. No idea why that is.

02-18-2015, 08:34 AM	#7
IceHand Linux User Posts: 323 Karma: 13682 Join Date: Aug 2007 Location: Germany Device: Kindle 3	I don't understand why FBReader isn't more popular. At least the desktop version that I tested on my Linux PC offers far superior font rendering with true kerning and even automatic ligatures. @bhaak: Well, freetype's kerning might be better than nothing, but it's far from ideal. I might take a look at HackedUpReader though, if I get a newer Kindle. @sadowski: Huh, that's weird. Even more so because Charis SIL has no kerning information included.

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