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Re: Multi image PDF continuous mode
From: |
Juri Linkov |
Subject: |
Re: Multi image PDF continuous mode |
Date: |
Mon, 10 Jan 2022 10:13:10 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (x86_64-pc-linux-gnu) |
> Okay, so I have got a working Proof of Concept / core functionality.
> You can very easily test it by loading the bookroll.el file from here,
> then do `M-x br-test` and scroll using `j`/`k`. I will now focus on trying
> to implement
> it into pdf-tools, which is probably a little more work as its code is
> quite complex/opaque.
One problem is that the vertical scroll bar doesn't allow scrolling all images.
>> Maybe then after a real image
>> will be scrolled out of view, it could be replaced with a placeholder again
>> to free memory.
>
> Haha, that is exactly what I meant with exactly that (the following)
> sentence.
This is nice that you already took care about this case.
> > 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.
>
> It would be nice to include pdf-tools in Emacs, but I don't know
> if the new maintainer has an intention to submit it for inclusion.
>
> > 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
>
> I agree, a real continuous scroll mode would be more preferable.
>
> > - 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
>
> While two-images approach could provide better optimization for memory,
> it has severe limitations, e.g. the vertical scroll bar can't be used
> to scroll all images at once.
>
> > but as I will describe now, I think it will be better to create a
> > 'bookroll' package for it.
>
> This is a promising direction.
>
> > 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
>
> Why not? 'image-roll' could be useful for the image gallery packages
> like image-dired.el and thumbs.el.
>
> > 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).
>
> Good news, so loading a 1000-page document won't take much memory.
> Only scrolling will load real images. Maybe then after a real image
> will be scrolled out of view, it could be replaced with a placeholder
> again
> to free 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.
>
> Thanks, feel free to post updates about your progress
> or when stuck on some problems.