Darkening and subsetting fonts

[roger64]

Hi

Here are the results of some trials.

To begin, you'll find four (there are more of them) otf fonts of the Linux Libertine O family. Please note that these fonts are published under the GPL license, and that the further modified and renamed fonts below share of course the same license. They are in the folder: "A original fonts".

These fonts have been darkened using the nice script of Sherman Perry, ReadifyFont.

The "latest" version can be found here: https://github.com/shermp/ReadifyFon...ceImprovements

I selected two different darkening levels from a range from 0 to 50 and modified accordingly their side-bearings: 30 is nearly a semi-bold value, while 20 is only neatly darker. I produced four ttf fonts, renamed LibertineO-G30 or LibertineO-G20. The Bold and BoldItalic fonts have not been darkened. These fonts can of course be installed permanently on your system or side-loaded in any decent ebook-reader (like Koreader). They are in the folder: "B darkened."

These darkened fonts have been subsetted with pyftsubset (a part of the fonttools project) against the list of characters named characters330 which contains the 110 unicode characters of the joint EPUB (the list is produced by the reports tool of the Calibre Editor). The subsets are in the folder: "C subsets."

I also joined the test EPUB with its subsetted -and darkened- fonts. It passes the epubcheck validation test.

About size

This way one can embed subsets of any font, including a customized one. Here the regular subset size used for the EPUB is about 44k, and the italic one, 37k (from a common 110 characters list).

As we make it work currently with a single list of characters, pyftsubset can provide a clear size saving advantage if the book use only both regular and italic fonts. This advantage could be greatly reduced, even nullified, if we had to include bold and bolditalics fonts.

[roger64]

This is how I did it even if there can be other ways. I used these scripts with Archlinux, but they can work on many other operating systems as long as you have a recent version of Fontforge and Python (and python-pip for Arch).

About pyftsubset

I failed to see who are its five authors and its maintainer. Anyway many thanks to them.

Here is some more information about its use. If I understand correctly, by default, it says that it preserves ligatures. As you can read in the attachment, it's quite an advanced tool.

First, if you do not have it yet,

sudo pip install fonttools

Then, prepare a work folder. We'll put here
- the ttf font (exported from the EPUB or downloaded from elsewhere), for example STSong.ttf
- a UTF-8 txt file named for example china.txt containing the characters (here Chinese) you wish to include in the subset. These characters can easily be copied for example from the last line of the Characters tab of the Calibre Editor reports tool.

To create the subset, just use this command

pyftsubset STSong.ttf --text-file=china.txt

It will create a subsetted font "STSong.subset.ttf" (12.9 k) with which you can replace the original one.

This way of creating a subset seems quite useful, for example if you have a book containing some words or expressions in some exotic language.

About ReadifyFont

Many thanks to Sherman Perry. Note that the GUI has been made clearer. You will find it here:
I used the GUI provided with the script. I could darken and generate ttf for a family of four fonts. The GUI was started with this command.

fontforge -script ReadifyFontGUI.py

note that to add multiple font files, you have to add them at the same time (the file chooser dialog allows multiple selection). The current system is designed that if you click the load button again, it assumes you want to load a a new font family.

[sherman]

I must admit that I haven't exactly kept my little GUI up to date
The "latest" version can be found here: https://github.com/shermp/ReadifyFon...ceImprovements

Goodness knows how well it works. The FontForge folks seem to change/add to the python api as it suits them, and don't exactly keep the documentation up to date (at least it seems that way). They also can't seem to decide whether they want to use Python 2 or 3, which is even more annoying.

Fonttools would be great to use, but as roger64 noted, it is a very advanced tool, however documentation on how to use the thing is.... sparse.

Note with my tool, that it seems to have real trouble with the internal font naming for a lot of fonts, and I don't know why.

[roger64]

@sherman

Thanks for the link to the new revamped interface.

Using Arch I still face the following glitch: even if the four squares (for normal, italic, etc.) are displayed, I can load only one font on the top line. If I try to load a second one, it only erases the first one and takes its place.

If I judge from other calibre-debug comments, these troubles may be related to some missing gtk library (?).

[roger@anterg ReadifyFont-InterfaceImprovements]$ calibre-debug ReadifyFontGUI.py
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
QCommonStyle::drawComplexControl: Control 1 not handled
QCommonStyle::drawComplexControl: Control 1 not handled
QCommonStyle::drawComplexControl: Control 1 not handled
QCommonStyle::drawComplexControl: Control 1 not handled

[JSWolf]

Why are you subsetting in a rather difficult way? Calibre makes subsetting trivial. Also, Linux Libertine is not a nice font.

[doubleshuffle]

Originally Posted by JSWolf

Also, Linux Libertine is not a nice font.

That's a matter of taste, don't you think? I've been using Linux Libertine as my standard e-reading font for quite a while now and am still very happy with it.

[sherman]

Originally Posted by roger64

@sherman

Thanks for the link to the new revamped interface.

Using Arch I still face the following glitch: even if the four squares (for normal, italic, etc.) are displayed, I can load only one font on the top line. If I try to load a second one, it only erases the first one and takes its place.

If I judge from other calibre-debug comments, these troubles may be related to some missing gtk library (?).

[roger@anterg ReadifyFont-InterfaceImprovements]$ calibre-debug ReadifyFontGUI.py
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.
QCommonStyle::drawComplexControl: Control 1 not handled
QCommonStyle::drawComplexControl: Control 1 not handled
QCommonStyle::drawComplexControl: Control 1 not handled
QCommonStyle::drawComplexControl: Control 1 not handled

Note that the name of the branch is a bit deceptive, I had every intention of upgrading the interface, but nothing of note actually happened. That just happens to be the latest code base at the moment.

Also note that to add multiple font files, you have to add them at the same time (the file chooser dialog allows multiple selection). The current system is designed that if you click the load button again, it assumes you want to load a a new font family.

[JSWolf]

I would like to know why is anyone recommending using scripts and complicated ways to subset fonts when Calibre does it so easily?

[Turtle91]

Perhaps they don't wish to use Calibre and are developing their own method??? That is a common practice among software developers.

[JSWolf]

Originally Posted by Turtle91

Perhaps they don't wish to use Calibre and are developing their own method??? That is a common practice among software developers.

But is it common to invent a square wheel?

[jackie_w]

Originally Posted by JSWolf

But is it common to invent a square wheel?

It depends whether there is a Focus Group or other committee involved in the decision-making.

[Terisa de morgan]

Originally Posted by JSWolf

But is it common to invent a square wheel?

It's not a square wheel if the only method involves much more software than you are interested in (install calibre only for subsettings fonts is like using a sledgehammer to crack a nut).

Originally Posted by jackie_w

It depends whether there is a Focus Group or other committee involved in the decision-making.

[JSWolf]

Originally Posted by Terisa de morgan

It's not a square wheel if the only method involves much more software than you are interested in (install calibre only for subsettings fonts is like using a sledgehammer to crack a nut).

If you go back and reread the OP's message, you'll see Calibre is installed and is part of the process.

Originally Posted by roger64

These darkened fonts have been subsetted with pyftsubset (a part of the fonttools project) against the list of characters named characters330 which contains the 110 unicode characters of the joint EPUB (the list is produced by the reports tool of the Calibre Editor). The subsets are in the folder: "C subsets."

The problem here is that Calibre's editor doesn't differentiate between regular, bold, italic, & bolditalic. So you don't get proper subsetting. You get get such by using the Calibre to do the subsetting.

So yes, it does seem to be inventing a square wheel.

[roger64]

Originally Posted by sherman

Note that the name of the branch is a bit deceptive, I had every intention of upgrading the interface, but nothing of note actually happened. That just happens to be the latest code base at the moment.

Also note that to add multiple font files, you have to add them at the same time (the file chooser dialog allows multiple selection). The current system is designed that if you click the load button again, it assumes you want to load a a new font family.

Thank you for this answer. That was precisely my mistake. I can indeed select the whole family (four fonts together).

I edited the first two posts to include your comments about your new GUI and about selecting a family of four fonts.

[BetterRed]

Originally Posted by JSWolf

But is it common to invent a square wheel?

Sure it is - especially when you want a bumpy night ride

BR