Plato: A document reader for PDF, ePUB, DjVu, etc.

[baskerville]

I'm releasing Plato 0.5.0 today.

Plato now has a built-in ePUB renderer, written from scratch, in addition to the renderer that mupdf provides. Although a few things are still missing (tables, lists, floats, borders, rtl, etc.), it seems to already have enough features to properly render most of the HTML and CSS encountered in ePUBs. The renderer uses absolute page numbers (one page for every 2048 bytes of markup). This allows me to only build the display list of the spine item that holds the current page number.

The algorithm used to break paragraphs into lines is the Knuth-Plass algorithm (1981). More precisely, there are at most three passes: first we try without hyphenation ; if it fails we hyphenate using the Knuth-Liang algorithm ; if it still fails, we try with a simpler algorithm, that has no limits on the stretching of glues. By introducing optional breaks within a word, we might break a ligature. And if we later unbreak this ligature, we might end up with a line length that doesn't match the length that was used by the algorithm. The way I deal with this problem is by redistributing the width difference into the line's glues. Knuth and Plass solved this problem by generalizing the penalty primitive into a {Pre,No,Post}Break tuple. This is described in Document Preparation Systems, 1982, pp. 221–242): I don't have access to this paper.

The CSS parser only supports simple selectors: name#id.class1.class2.⋯.classn and the following combinators: X > Y, X + Y. If you're interested in typography and high quality fonts, you'll be happy to know that font-feature-settings is supported. Finally, I thought it would be interesting to be able to achieve some of the constructions made possible by the box–glue–penalty primitives described in the original paper, and for this purpose, I've introduced the custom `-plato-insert-{before,after}` properties. The solution to the MR Problem, for example, can be transposed as:

.flush-right {
	-plato-insert-before: penalty 10000, glue 0 100em, penalty 50,
	                      glue 1em, box, penalty 10000, glue 0 100em;
	-plato-insert-after: penalty -10000;
}

Embedded fonts are ignored, A declaration of the form font-family: A, …, Z, K is parsed as font-family: K where K is one of the following keywords: serif, sans-serif, monospace, cursive, fantasy.

You can set the serif font family, font size, margin width, line height of a document. The default values are in the reader section of the settings. The font-path setting of the same section defines the location of the user fonts (the default is /mnt/onboard/fonts).

The built-in ePUB engine is the default engine, the related setting, in the reader section is epub-engine, the possible values are "built-in" and "mupdf".

Because the type of the refresh-every setting has changed, you'll need to remove it from your Settings.toml before you upgrade.

Other changes:

• The automatic importer now retrieves metadata from ePUBs.
• The shelf's second column now displays the progress status by default. The corresponding setting, in the home section, is second-column, the possible values are "progress" and "year".
• The Clara HD was added to the list of devices.

[pickyaxe]

Just wanted to say this is an impressive project and to thank you for all the work you continue to put into it!

[geek1011]

Originally Posted by baskerville

Plato now has a built-in ePUB renderer, written from scratch, in addition to the renderer that mupdf provides.

Your ePub renderer is really impressive. The code looks quite nice, and it actually works well for most of my books. I especially like the way you handled the layout. Keep up the great work!

[neoberg]

Hello,

I am not a big fan of KSM or other menus and I use my Kobo mainly for XCSoar. How can I run Plato directly from command line ?(So I can add a menu item for running Plato to my XCSoar build)

When I run it like './plato' its giving this error:

./plato: error while loading shared libraries: libdjvulibre.so.21: cannot open shared object file: No such file or directory

Quick edit: I was trying to solve this yesterday evening and now just after asking this, I had the idea of moving to contents of ./lib to the same folder with the executable It worked.

Another edit: If I don't stop nickel, nickel and plato are racing for touch events and screen updates. If I stop it, plato's ui renders very small and can't handle touch correctly any ideas?

[baskerville]

Originally Posted by neoberg

If I don't stop nickel, nickel and plato are racing for touch events and screen updates. If I stop it, plato's ui renders very small and can't handle touch correctly

There're currently two ways of launching Plato.

• The fmon launcher assumes that Nickel is running, kills it, and restarts it when Plato quits.
• The standalone launcher assumes that Plato is started at the very end of /etc/init.d/rcS (cf. firmware.patch), instead of Nickel.

The binary needs a few environment variables and all the resources included in plato-0.5.0.zip.

[neoberg]

Originally Posted by baskerville

There're currently two ways of launching Plato.

• The fmon launcher assumes that Nickel is running, kills it, and restarts it when Plato quits.
• The standalone launcher assumes that Plato is started at the very end of /etc/init.d/rcS (cf. firmware.patch), instead of Nickel.

The binary needs a few environment variables and all the resources included in plato-0.5.0.zip.

Thank you, I'll try running it at the and of the rcS. It works for me since XCSoar restarts the system to run Nickel, too.

[CH23]

Hi baskerville,

I wanted to congratulate you on making such a nice application, and add that it works well on the Clara HD.

If you need anything tested, I'm more than willing to help.

[jcn363]

Originally Posted by baskerville

There're currently two ways of launching Plato.

• The fmon launcher assumes that Nickel is running, kills it, and restarts it when Plato quits.
• The standalone launcher assumes that Plato is started at the very end of /etc/init.d/rcS (cf. firmware.patch), instead of Nickel.

The binary needs a few environment variables and all the resources included in plato-0.5.0.zip.

It works with kfmon too.
Good luck.

[baskerville]

Plato 0.5.1 was released.

• It is now possible to wake from suspend at any point in time.
• The go to page input field now handles relative page jumps. You can jump to the n-th page after (resp. before) the current page with +n (resp. -n).
• The information shown in the second column of the book's stripe can be changed through the Second Column submenu of the library menu.

I should have mentioned this earlier, although I don't think it will have a tremendous impact on the user experience, but the built-in ePUB renderer will not work with books with more than 2 million pages.

[danielr]

Is it possible to put the menus in Spanish?

[Dirk-71]

A step-by-step guide for novices would be beneficial. The guide on github is not for people who are no developers. plato.sh? plato.png? Where do I find it???? A bit confusing to me.

[jcn363]

KFMON
* Extract the full content of kfmon archive into the root directory of your device.
* Extract the content of the zip into the .adds/plato directory of your device.
* You need a /.adds/kfmon/config/plato.ini and an /icons/plato.png.
* Eject and unplug your device.

The guide for KSM and fmon.

Good luck.

[tlc630]

Hi,

First I would like to congratulate you on this project. It is a real pleasure to use with a very attractive appearance and 'feel'.

But, I just installed version 0.5.1 on my Glo and the the frontlight no longer works. Pressing the light icon does nothing. I reverted to v 0.5.0 and the light works. Any ideas on what I should try to isolate the problem?

My environment is:
Kobo Glo
Software v 4.8.11073 (b628114af7,5/8/18)
KFMon v 1.2.6-1-g9ab7d3a

Thanks!

[baskerville]

Originally Posted by tlc630

Pressing the light icon does nothing.

This can only happen if the frontlight is disabled.

Can you:

• Toggle the frontlight by holding the frontlight icon?
• Bring up the main menu by tapping the main menu icon?

[Dirk-71]

Originally Posted by jcn363

.....
The guide for KSM and fmon.
......
Good luck.

Thank you! I'll give it a try!