Several kobopatch config questions

[Antioch]

Hello! I'm new to patching and would like to try. I've read the readme and the yaml config docs but I have several questions regarding some of the configurations. I would appreciate any replies I can get.

1. Do the "custom font sizes" and "unify font size" patches work together or are they mutually exclusive?
2. What is the difference between the "custom sleep/power-off timeouts" and "larger sleep/power-off timeouts" patches? I've checked the "larger" config generator webpage but am not satisfied with the time options it provides (I don't mind that they're not even numbers, but do the limitation in range). The "custom" one looks to provide much more straightforward time options but I'm unsure if I can directly edit the values in the yaml. Specifically, I'd like to set sleep to 10m and power off to 48h or 72h. (Am not using a sleep cover)
3. Where can I find "KePub stylesheet additions - optimizeLegibility"? Notes say this was released in v74, but I don't see it in the yamls that comes with kobopatch_4.30.18838 (which is the patch version I'm working against).

Additionally, I'm experiencing an odd issue where the right margin is visually smaller than the left margin. After increasing/decreasing the margins on-device, it looks like the right and left sides scale at a slightly different rate?

I've enabled "Custom kepub default margins" and have the following in my kobo_extra.css (which I set KoboTouchExtended to use when generating kepubs):

@page {margin: 8pt 0 0 0}
div, p {widows:1; orphans:1;}

My margins are usually set to the 1st or 2nd smallest settings, but I notice that the amount of visible margin on the device is not the same on each side when reading and it bothers me. Does anyone have any idea what's going on?

(Maybe my screen is not evenly set in the device? )

Thank you!

[Sirtel]

1. They're not mutually exclusive. I use both of them.

Sorry, I don't use the rest in your list, so can't answer those.

[jackie_w]

Originally Posted by Antioch

[*]Where can I find "KePub stylesheet additions - optimizeLegibility"? Notes say this was released in v74, but I don't see it in the yamls that comes with kobopatch_4.30.18838 (which is the patch version I'm working against).

This patch (or rather, its predecessor) stopped working in fw 4.28.xxxxx. I only added it back to the standard kobopatch pack in the fw 4.31.19086 release. It only existed as a beta patch on the GitHub site for fw 4.28.xxxxx, 4.29.xxxxx and 4.30.xxxxx.

However, the version for 4.31.19086 works quite happily as-is in 4.30.xxxxx because nothing relevant changed between 4.30 and 4.31 for this particular patch.

You can copy the patch KePub stylesheet additions - optimizeLegibility from here (it's the last patch on that page). Paste it into your existing copy of libnickel.so.1.0.0.yaml before enabling it.

[jackie_w]

Originally Posted by Antioch

Additionally, I'm experiencing an odd issue where the right margin is visually smaller than the left margin. After increasing/decreasing the margins on-device, it looks like the right and left sides scale at a slightly different rate?

I can't say I've ever experienced asymmetric left/right page margins.
Are you sure it's not related to a specific book which specifies unequal L/R margins in its body{...} CSS?

Originally Posted by Antioch

I've enabled "Custom kepub default margins" and have the following in my kobo_extra.css (which I set KoboTouchExtended to use when generating kepubs):

@page {margin: 8pt 0 0 0}
div, p {widows:1; orphans:1;}

If you're using KoboTouchExtended to send your epubs to the Kobo as kepubs then you need to be aware that kepubs ignore all @page, widows, orphans CSS. You'll only see the effect of your kobo_extra.css (as posted above) for epubs which you used calibre to transfer as standard epubs, i.e. books sent using KoboTouchExtended with the box Enable Extended Kobo Features un-checked.

[Antioch]

Originally Posted by Sirtel

1. They're not mutually exclusive. I use both of them. ...

Originally Posted by jackie_w

... However, the version for 4.31.19086 works quite happily as-is in 4.30.xxxxx because nothing relevant changed between 4.30 and 4.31 for this particular patch. ...

Thank you both very much for that information.

@Jackie_w, is it possible to only enable kerning and not ligatures?

Originally Posted by jackie_w

I can't say I've ever experienced asymmetric left/right page margins.
Are you sure it's not related to a specific book which specifies unequal L/R margins in its body{...} CSS?

I don't think it's a problem with the CSS. Granted, I'm not very well versed with CSS, but from what I can see it looks like the left and right margins are always set to the same value in every tag I could find. Moreover, the l/r margins appear to be symmetric in the Calibre reader.

Maybe my eyes/brain are playing tricks on me! However, with 0 margin on the device it really does look like the rightmost 1 or 2 pixels are cut off. Perhaps the screen isn't centered. Is there a way to add 1 or 2 pixel margin-right to all kepubs?

Originally Posted by jackie_w

If you're using KoboTouchExtended to send your epubs to the Kobo as kepubs then you need to be aware that kepubs ignore all @page, widows, orphans CSS. You'll only see the effect of your kobo_extra.css (as posted above) for epubs which you used calibre to transfer as standard epubs, i.e. books sent using KoboTouchExtended with the box Enable Extended Kobo Features un-checked.

Also, thank you for the information regarding kobo_extra.css. I had been exclusively using epubs on my Aura H2O but with my new Libra 2 I'm trying to use kepubs and was unaware that the kepub reader didn't use those settings. However, the KTE driver seems to inject this CSS into the kepub it creates if the "modify css setting" is enabled - is this not true?

https://github.com/jgoguen/calibre-k...bitrary-styles

... If you have created the kobo_extra.css file on your Kobo device already and you want to make use of this feature, you must copy kobo_extra.css to the calibre plugin directory.

Is there some other way (patch or otherwise) to replicate my kobo_extra.css settings in the kepub reader?

@page {margin: 8pt 0 0 0}
div, p {widows:1; orphans:1;}

[Antioch]

I'm curious if anyone knows what is going on with the word spacing in these examples? Specifically looking at the first line of the second paragraph.

The screenshots are as follows:
1. KePub with patched firmware (excluding legibility patch)
2. ePub (same firmware as #1)
3. KePub with same firmware as #1 + legibility patch

(Note: KePub was converted with KoboTouchExtended driver)

Here are my firmware patch settings:

Spoiler:

Patching ./usr/local/Kobo/libnickel.so.1.0.0
  SKIP  `Allow USB storage even when device locked`
  SKIP  `Allow rotation on all devices`
  SKIP  `Allow showing info panel on random screensaver`
  APPLY `Always show confirmation dialog before upgrading`
  SKIP  `Block WiFi firmware upgrade`
  SKIP  `Both page turn buttons go next`
  SKIP  `Both page turn sides go next`
  SKIP  `Bulgarian Phonetic Keyboard (GloHD/ClaraHD/AuraOne/H2O2/Forma/Libra)`
  SKIP  `Change Browse Kobo home screen link target - Activity`
  SKIP  `Change Wikipedia search language`
  SKIP  `Custom Sleep/Power-off timeouts`
  APPLY `Custom font sizes`
  SKIP  `Custom header/footer page number text`
  APPLY `Custom kepub default margins`
  APPLY `Custom left & right margins`
  SKIP  `Custom navigation menu page number text`
  SKIP  `Customize ComfortLight settings`
  SKIP  `Cyrillic Keyboard (GloHD/ClaraHD/AuraOne/H2O2)`
  SKIP  `DeveloperSettings - AutoUsbGadget`
  SKIP  `Dictionary text font-family/font-size/line-height`
  SKIP  `Disable all tutorial dialogs`
  SKIP  `Don't grab exclusive access to event0`
  SKIP  `Don't uppercase header/footer text`
  SKIP  `Don't uppercase header/footer text and change page number text`
  APPLY `Enable advanced settings for all fonts`
  SKIP  `FeatureSettings - BookSpecificStats`
  SKIP  `FeatureSettings - ExportHighlights`
  SKIP  `FeatureSettings - FullScreenBrowser`
  SKIP  `FeatureSettings - MyWords`
  SKIP  `FeatureSettings - ShowFacebookShare`
  SKIP  `Force user font-family in ePubs (Part 1 of 2)`
  SKIP  `Force user line spacing in KePubs`
  SKIP  `Force user line spacing in ePubs (part 1 of 2)`
  SKIP  `Greek Keyboard (GloHD/ClaraHD/AuraOne/H2O2)`
  SKIP  `Hide browser from beta features`
  APPLY `Ignore .otf fonts`
  SKIP  `Increase page navigation history`
  SKIP  `KePub constant font sharpness`
  APPLY `KePub stylesheet additions - optimizeLegibility`
  SKIP  `KePub stylesheet additions - optimizeSpeed`
  SKIP  `KePub stylesheet additions - text justify`
  SKIP  `Larger Sleep/Power-off timeouts`
  SKIP  `My 10 line spacing values`
  SKIP  `My 24 line spacing values`
  SKIP  `Never show Kobo Plus, wishlist, and points SmartLinks`
  SKIP  `Only show Pocket SmartLink`
  APPLY `Only show stats SmartLink`
  SKIP  `PowerSettings - UnlockEnabled`
  SKIP  `Remove beta features not supported text`
  SKIP  `Remove line from bottom tab bar`
  SKIP  `Remove recommendations (row1col2) from home screen`
  SKIP  `Remove title from reading header/footer`
  SKIP  `Rename new home screen footer`
  SKIP  `Replace adobe page numbers toggle with invert screen`
  SKIP  `Set KePub hyphenation`
  SKIP  `Set visible SmartLink`
  SKIP  `Shorten dictionary entry not found message`
  SKIP  `Swap reading header/footer`
  APPLY `Un-Force user font-family in KePubs`
  APPLY `Un-Force user text-align in div,p tags in KePubs`
  SKIP  `Un-force font-family override p tags (std epubs)`
  SKIP  `Un-force link decoration in KePubs`
  APPLY `Unify font sizes`
  SKIP  `ePub constant font sharpness`
  SKIP  `ePub disable built-in body padding-bottom`
  SKIP  `ePub fixed top/bottom margins`

Patching ./usr/local/Kobo/nickel
  SKIP  `Change TOC level indentation`
  SKIP  `Custom collection/author header title font`
  SKIP  `Custom header/footer captions`
  SKIP  `Custom page navigation scrubber`
  SKIP  `Custom synopsis details line spacing`
  SKIP  `Custom synopsis font size`
  SKIP  `Customise Header back button`
  SKIP  `Dictionary pop-up - increase available text area`
  SKIP  `Increase Book Details synopsis area`
  SKIP  `Increase headlines font`
  SKIP  `Increase home screen cover size`
  SKIP  `Increase library cover size`
  SKIP  `Increase size of kepub chapter progress chart`
  SKIP  `New home screen subtitle custom font`
  SKIP  `Reduce new header/footer height`
  SKIP  `Reduce top/bottom page spacer`
  SKIP  `Remove footer (row3) and increase cover size on new home screen`
  SKIP  `Remove footer (row3) on new home screen`
  SKIP  `Remove forgot pin button from lock screen`
  SKIP  `Series list increase cover thumbnails`
  SKIP  `Show all games`

Patching ./usr/local/Kobo/libadobe.so
  SKIP  `Remove PDF map widget shown during panning`

Patching ./usr/local/Kobo/librmsdk.so.1.0.0
  SKIP  `Default ePub monospace font`
  SKIP  `Default ePub sans-serif font (Gill Sans)`
  SKIP  `Default ePub serif font (Amasis)`
  SKIP  `Default ePub symbol font (Symbol)`
  SKIP  `Disable orphans/widows avoidance`
  SKIP  `Force user font-family in ePubs (Part 2 of 2)`
  SKIP  `Force user line spacing in ePubs (Part 2 of 2)`
  SKIP  `Ignore ePub TOC navpoints`
  SKIP  `Ignore ePub book Adobe XPGT stylesheet (page-template.xpgt)`
  SKIP  `Ignore ePub book CSS and Adobe XPGT stylesheets`

And here are the reader configs from "Kobo eReader.conf" for reference:

Spoiler:

[Reading]
DarkMode=falsechapterProgressType=3
numPartialUpdatePageTurns=1
readingAdobeShowPageNumbers=false
readingAlignment=
readingFontFamily=Georgia
readingFontSize=36
readingLeftMargin=3
readingLineHeight=1
readingRightMargin=3
showProgressBar=false

What I see going on here:
A. Extra spacing between words in KePub causing words to be moved the next line compared to ePub. Perhaps due to a minor difference in margins impacting line width?
B. With kerning (legibility patch) enabled there is extra spacing between letters in KePub compared to without kerning enabled. I expected the opposite: a reduction in spacing.
C. Maybe line spacing is larger in KePub than ePub? Not sure, but not too concerned with this.

Help is much appreciated!

[JSWolf]

Originally Posted by Antioch

@Jackie_w, is it possible to only enable kerning and not ligatures?

In order to enable kerning, you have to make sure the font being used supports legacy kerning. You can use Fontforge to save the font with legacy kerning. See this thread on how to do it.

https://www.mobileread.com/forums/sh...d.php?t=259102

[Antioch]

I did some I-have-no-idea-what-I'm-doing sleuthing and think I have figured out what is causing the word spacing discrepancies:

The fonts aren't set to exactly the same size in the kepub and epub renderers. That is, I don't think that the "unify font size" patch makes both sizes exactly the same?

I zoomed in to the two screenshots and noticed that there is a slight shadow around the kepub's text (most discernable around the upper edges of 'T') which suggests to me that the font is scaled ever so slightly larger than the epub's thus causing "afterglow" to not fit on the same line.

This might also have a very minute effect on C (line spacing), as well?

Of course, the programmers know exactly what is going on with that patch and can let me know that my guess is wrong.

(kepub on left, epub on right - zoomed 1000%)

[jackie_w]

Originally Posted by JSWolf

In order to enable kerning, you have to make sure the font being used supports legacy kerning. You can use Fontforge to save the font with legacy kerning. See this thread on how to do it.

https://www.mobileread.com/forums/sh...d.php?t=259102

No, you really don't have to do all that. If you have included

text-rendering: optimizeLegibility

in the kepub CSS (via kobopatch, kobo_extra.css or any other preferred method) then kerning and ligatures will be used. See my old 2016 post with pics.

[jackie_w]

Originally Posted by Antioch

The fonts aren't set to exactly the same size in the kepub and epub renderers. That is, I don't think that the "unify font size" patch makes both sizes exactly the same?

That may be true. @sherman had to completely rewrite that patch when it stopped working quite recently (4.28.xxxxx perhaps???) due to major Kobo changes. I believe it was a lot of work to get the epub/kepub font-sizes as close as they are without worrying whether they're pixel-perfect. Near enough is good enough

Given some of your kerning questions, I think it may be worth you reading the whole kepub vs. epub thread. It's only 3 pages of posts so shouldn't take too long. It's where the text-rendering: optimizeLegibility pros/cons were first discussed.

[JSWolf]

Originally Posted by jackie_w

No, you really don't have to do all that. If you have included

text-rendering: optimizeLegibility

in the kepub CSS (via kobopatch, kobo_extra.css or any other preferred method) then kerning and ligatures will be used. See my old 2016 post with pics.

Thank you for that. It will help for KePub.

I do appreciate all the help you and others give.

[NiLuJe]

Keep in mind that both engines use *completely* different font renderers, so I don't expect a 1:1 pixel-perfect match, even for something "slightly" (he said ;p) more trivial as baseline and glyph blackbox handling to actually be technically feasible .

As a not-really-applicable-here, but highly interesting, and tangentially related read, see https://gankra.github.io/blah/text-hates-you/ .

[Antioch]

Originally Posted by jackie_w

Given some of your kerning questions, I think it may be worth you reading the whole kepub vs. epub thread. It's only 3 pages of posts so shouldn't take too long. It's where the text-rendering: optimizeLegibility pros/cons were first discussed.

Thank you. I've read the thread and, yes, it seems like I also notice and am annoyed by the div induced spacing issue that is caused by justification + optimizeLegibility. That thread is several years old, however -- has a workaround been developed in recent years?

The only issue I really had with RMSDK was with page numbering. I strongly disliked that the displayed page numbers didn't match with page turns: I would often turn a page and the page number didn't increment. This made it impossible to estimate how much longer I had remaining in each chapter. Is it correct to assume that this isn't "fixable" by a patch?

[sherman]

Originally Posted by Antioch

The only issue I really had with RMSDK was with page numbering. I strongly disliked that the displayed page numbers didn't match with page turns: I would often turn a page and the page number didn't increment. This made it impossible to estimate how much longer I had remaining in each chapter. Is it correct to assume that this isn't "fixable" by a patch?

I'm afraid not. RMSDK page numbering is basically based on a word/character count, and there's no way to change it.

I'm one of the people who prefer that. It means I know exactly how long a book is, no matter the font size, margins, line spacing etc.

As for the unify font size patch, there's no way to get it pixel perfect. My goal was to get it as close as possible, but the multipliers/divisors I have to work with can only be set in 0.25 increments. Also, as NiLuJe said, kebup and epubs use completely different font renderers.

[sherman]

Just something I've remembered with regards to margins in epub files.

Until recently, it was quite common for commercial epubs to contain RMSDK specific .xpgt stylesheets, which usually contained margin settings. Most other software - including Calibre - does not read these stylesheets. But Kobo ereaders do.