export fixed layout and prospectively enhance Vivliostyle pagination algorithm

[thomas-topway-it]

Is your feature request related to a problem? Please describe.

Shouldn't an epub viewer able to paginate an epub with reflowable layout considered a publishing and design software primarily aimed to publishers ? (or advanced readers who want a digital edition tailor made on their device)

In this view most of the epub readers on the market do not appropriately distinguish between readers and publishers, and overload their apps or viewers with features aimed to publishers or advanced readers (i.e. readers that actually play the role of publishers) that aren't suitable for a protected and friction-less reading experience.

Describe the solution you'd like Vivliostyle Viewer already includes a right sidebar where the user (mainly a publisher) can set-up their editions, based on page size, margins, widows/orphans control, additional css and so on. Vivliosyle core could therefore just feature an export api completed with an export button in the reader, so that the edition can be exported with a fixed layout corresponding to the current settings.

This also enhances the user/reading experience, since once that an user/reader (i.e. not a publisher) has chosen or also created their own edition, he/she does not play with the interface anymore (except that for reading actions, like scrolling, to highlight text, etc.) and can focus on reading.

Describe alternatives you've considered Fixed-layout EPUBs is a new Epub3 specification and has a great potential yet to be adopted and implemented https://idpf.org/epub/fxl/epub-fxl-20120313.html https://www.w3.org/TR/dpub-aria-1.0/#doc-pagebreak

Additional context Pagination is a difficult task! If performed appropriately (see reference below) it takes a non-negligible time and there is no reason to not save a pagination result ! Also, to save a pagination result is the only way to perform pagination reasonably well with an appreciable user experience

https://www.latex-project.org/publications/2019-FMi-coin12165-final.pdf http://www.eprg.org/G53DOC/pdfs/knuth-plass-breaking.pdf http://www.infogridpacific.com/blog/igp-blog-20130922-epub3-accessibility-and-pagebreaks.html