After reading this thread, and especially after reading this
message by Eli (if
the links don't work, I have attached them also at the end), I have again looked
into this. I would like to share my perspective on this, but before I do that,
let me first ask you if you have any idea about why pdf-tools is not part of
Emacs. It is a very high quality package, that already lazily loads the images,
and provides many sophisticated features.
You might already be familiar with my
2-buffer continuous scroll hack for it
(which can be easily ported to doc-view mode, but 'developing' a 'real'
continuous scroll mode solution makes much more sense, and, if possible, to me
it would make even more sense to try to get pdf-tools into Emacs).
Some related interesting announcements are that:
- I have written an alternative server for pdf-tools, which uses the
pymupdf library. You can read more about it in the
PR. A nice thing about its design
is that it uses the python interpreter/REPL directly as a server (it reads
messages and prints to standard output). It already extends/complements the
features of the original epdfinfo server by supporting line/arrow annotations
and supporting the EPUB format very nicely. Additionally, it enables other non
C programmers to extend its features (e.g. support for freetext annotations
should be only little work).
- I have created a, very rude but already nicely working, 'real' continuous
scroll proof of concept, for which, if you are interested, you can find the
code in this
commit. It currently uses a trick where it only uses two images
at the time, but as I will describe now, I think it will be better to create a
'bookroll' package for it.
The 'continuous' rendering is only part of implementing continuous scroll into
pdf-tools because it would also be nice if it could be made compatible with all
pdf-tools its features. After investigating how to achieve that, I have come to
the conclusion that we need a 'bookroll' alternative to 'image-mode', because
the main obstacle is that pdf-tools now uses image-mode functions, that are
written only for a single overlay per buffer.
I think the bookroll should not be so difficult to implement (I first started to
think about a general 'image-roll', but I think continuous scrolling is
generally not what you want for viewing/scrolling images, so it can be just a
dedicated bookroll). So my current idea for how to implement it, is by
immediately creating overlays for all pages in a single buffer and fill them
with 'empty' svg-images of the correct size (after testing this with a thousand
'placeholders', it seems that the 'empty' images use almost no memory). Then,
the scrolling can be implemented, by changing the display properties (from empty
svg to real image, and back) and jumping to the correct positions using
`set-window-vscroll`. I have started on writing bookroll.el, of course your
joined efforts or feedback would be very much appreciated. Otherwise, this short
message serves just to inform you about these activities.
Finally, it would be great if you could share your 'knowledge' about why
pdf-tools is not in Emacs. Its main developer has stepped down from the project,
and 'vedang' has taken the roll of new maintainer. Anyway, I guess we could best
ask the former and current maintainers as soon as possible about thier
'opinions' and for signing the necessary papers.