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Re: Some options for vertically-scrollable manga (was re: Dropbox has epub viewer)

From: Hadrien Gardeur <hadrien.gardeur@feedbooks.com>
Date: Wed, 20 Jun 2018 11:17:56 +0200
Message-ID: <CA+KS-13k3Gt9MFG9y_izk9L4xH+C1YuudpD5ApLueYBvSHFXSg@mail.gmail.com>
To: Florian Rivoal <florian@rivoal.net>
Cc: MURATA Makoto <eb2m-mrt@asahi-net.or.jp>, Joshua Pyle <jpyle@atypon.com>, ryladog@gmail.com, W3C Publishing Working Group <public-publ-wg@w3.org>
Hello Florian,

The right approach also depends what target you're considering.

It's a very different choice if we're talking EPUB 3.2 or Web Publication.

In practice, this is indeed true. At the same time, I don't think UAs are
> strictly required to hold all images in memory all the time. They typically
> do, but a UA optimized for low footprint could flush them to disk when out
> of the viewport, and load them on demand when needed.

This is something very hard to do for most EPUB reading systems out there.
In practice, most apps are stuck with the default behaviour and APIs
available for a webview.

To optimize for low footprint, you'd probably have to do some JS trickery
that would block images from loading while off-screen, but I can imagine
quite a few side effects (including the fact that JS is not well supported
in such readers, especially on reflowable resources).

The fact that the viewport is unpredictable is a feature, not a bug: it is
> the natural consequence of allowing people to read on any device they want.
> The question is what can an author do in response to viewport size changes,
> and CSS gives quite a lot of flexibility. It is possible to use:
> * the width, height, max-width, max-height, min-width, min-height either
> on the image container, or on the images individually, to control their size
> * the px, %, vh (viewport height) or vw (viewport width) units when doing
> so
> * the object-fit property to decide what to do if the image's size or
> aspect ratio does not match the size or aspect ratio imposed by the
> width/heigh/etc properties https://developer.mozilla.org/
> en-US/docs/Web/CSS/object-fit
> * media queries to switch layout at different sizes
> * CSS Grid to provide different non-linear, possibly overlapping,
> arrangement as desired, for example at large screen sizes.
> * css scroll snap to force the UA to scroll step-by-step / image-by-image
> if desired.

This is all true for WP, but keep in mind that for EPUB right now, most of
the properties that you're listing would be:

   - unsupported or unavailable
   - overwritten by the RS that injects its own CSS instead

Could you clarify what's the target for this vertically-scrollable manga

Received on Wednesday, 20 June 2018 09:18:48 UTC

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