[Okular-devel] Improving the book reading experience with KDE tech

[Inge Wallin]

On Sunday, December 23, 2012 03:09:28 Albert Astals Cid wrote:
> El Diumenge, 23 de desembre de 2012, a les 01:18:23, Inge Wallin va 
escriure:
> > In just a few weeks Calligra 2.6 will be released, and with that the
> > first version of Calligra Author. The first version of Author will be
> > very like Words but it has a focus on the needs of a book writer rather
> > than, say, a report writer or a memo writer. Therefore we expect Words
> > and Author to start to diverge in the feature set soon.
> > 
> > Version 2.6 of Calligra Author has support for creating ebooks in EPUB2
> > and MOBI formats. Both of these formats are rather simple and support
> > text with various formatting and pictures. Okular has a generator for
> > EPUB which makes it a decent basic ebook reader.
> > 
> > However, Calligra Author 2.7 will start producing EPUB3 files which are
> > much more complex.
> 
> How different EPUB3 vs EPUB2 are in file-format?

The file structure is exactly the same: a zip store that contains html files 
(the chapters), an xml-based table of contents, a manifest and other resources 
like pictures, etc. The difference is in what is allowed. EPUB3 adds:
 - Multimedia contents
 - MathML
 - Other extended web standards such as x3dom, etc
 - accessibility
 - more advanced css styling, including some that is specially created for 
online magazines
 - ...more that I don't remember from the top of my head.

> > I want Author to become *the* way to create teaching
> > materials with dynamic contents (animations, multimedia, etc) but most of
> > that will be meaningless if there is no way to read the generated files.
> > EPUB3 is huge so Author 2.7 will start out by supporting embedded videos
> > and embedded math formulas using MathML.
> > 
> > And this is where Okular falls short. The current generator does not
> > support more than very basic formatting and math formulas is not part of
> > that. And the whole API of Okular does not support anything but static
> > content.
> 
> We have support for videos (not sure if the Active frontend supports those)

I'm very happy to hear this.

> > In
> > the long run, this lack will diminish the value of Plasma Active and
> > therefore I have also added the Active ML as a recipient.
> > 
> > Call to action
> > -------------------
> > 
> > I would like to put together a small task force to enhance Okular with a
> > better generator for EPUB as well as enhance the general engine to also
> > allow dynamic contents. The first version should support video but in the
> > future i can easily imagine other things like embedded scripted
> > animations or 3D objects in X3Dom and so on.
> 
> As said we already support videos (not in epub but in pdf) so the
> infrastructure is there, you "just" need to wire it. Pino also did a proof
> of concept PDF-3D support ages ago, so it's nothing impossible to do,
> "just" needs some time ;-)

Got it. What is PDF-3D?  Some extension for 3D objects in a PDF?  How about 
mathematics?

And btw, how about reflowable contents? I think we discussed this on IRC some 
time ago. I have rethought it and I don't think it is super important any more 
but still... EPUB is defined as reflowable so in the long run it should be 
supported by any good book reader.

> > I have looked at the code of Okular and it looks entirely doable. I could
> > probably manage myself but then there would be no other work on Calligra
> > Author for the 2.7 cycle and that would be bad.
> > 
> > I think this is an important task for PA4 and therefore Okular Active.
> > 
> > Any takers?
> 
> I guess the first step is making sure we are able to read EPUB3 at the same
> level of EPUB2 and then have a look at the extra features.

That we are already because EPUB3 is just EPUB2++. :)

> I can't commit to the development of that, since i'm faaaaaaaaar to
> stretched already in billions of stuff but if you need help wiring stuff
> up or navigating through the okular architecture I'm happy to help both
> here or in the #okular IRC channel.

Thanks a lot. That will help.  

I was thinking of experimenting with a qwebkit based generator instead of the 
current qtextdocument based one. Another alternative is to use the more 
advanced text layout of the calligra text engine which is also based on 
qtextdocument but extends it considerably.

	-Inge

> Cheers,
>   Albert
> 
> > 	-Inge
> > 
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