Hello okular (and kde) devs,

In the last some years I have noticed the .epub format increasing. I understand
the reasons why .epub is used more, but I am having some problems with this
format; in particular it takes quite some time for it to open in okular here,
much more so than typical .pdf files with the same amount of pages.

This is my primary use case for this request, actually - I would prefer .pdf
files in this case. (Or do the conversion into .pdf, while keeping the .epub
file as well)

So, I am just opening a few .epub files right now in okular and I notice the
"Save as" option - but we can only save as .epub or okular document format,
unfortunately.

I would like to ask whether it would be possible to add a "to pdf" save as operation
here, for okular.

I am totally fine if not everything can be saved when an .epub is converted into a .pdf
file, I really just need plain oldschool .pdf files. A warning/notification could be issued
to the user if this is the case, so that the user may know that not everything can be 
converted; that way other users would know that this is a lossy exchange, but it would 
still be a new possibility for okular.

Perhaps even a commandline-only way for this operation, then I could use e. g. ruby to
call system() and batch-convert the .epub files through okular. (Evince does not even
have support for .epub files, which I find strange; yes, .epub is not like .pdf, but
people use it in a VERY similar way if you ask me. On the GNOME bugtracker some of
the devs pointed out to use something else, such as calibre. I think the approach
taken by okular is better and I actually think that evince will eventually get
.epub support, despite what these individual devs stated otherwise.)

Anyway, not sure whether this is wanted or would be too much work for okular, but I
guess since the KDE stack + okular already handles .pdf and .epub, perhaps a "save
as .pdf format" option may be something to consider for the future.

Thanks for reading! Please disregard if it is unwanted functionality or may
be too difficult to add; I understand time constraints. It just seems like
a good time right now considering that okular has been quite active in 
seeing changes (the recent annotation changes for example).