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RE: [css-snappoints] [css-scroll-snap] Summary of latest updates 1/13

From: Matt Rakow <marakow@microsoft.com>
Date: Wed, 20 Jan 2016 14:55:44 +0000
To: fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <BY2PR03MB3611C391F140BA158707E0BADC20@BY2PR03MB361.namprd03.prod.outlook.com>
> As far as 'scroll-snap-align' goes, I think in most cases the important consideration is the logical direction, not the physical one. Consider bidi cases: if you're snapping a side edge, it's almost always going to be the start edge you care about, not the left/right edge specifically, because that's what matches up to the direction of scrolling. Similarly for vertical text: if you're snapping to the top edge in horizontal text, you definitely want to be snapping to the block-start edge in vertical writing modes, not to the block-end edge in any case!

This assumes the content you are snapping is primarily text.  On the contrary, the most common scenarios are not text -- hero flippers (e.g. MSN.com), product catalogs (e.g. Amazon.com), filmstrips (e.g. Flickr.com), etc. are more prevalent by far.  Even many scenarios which seem to be primarily text (e.g. address book on a phone) typically don't change orientation on writing mode, preferring to maintain the ergonomics of a particular scrolling direction.

To clarify, the scenario I am concerned about is something like this:

.horizontalFlipperWidget {
    overflow-x: scroll;
    scroll-snap-align: center none;
    scroll-snap-type: mandatory;
}

This is the number one scenario for snap points, I'd like it to not break by default in vertical writing mode.

> Well, we do want to make sure that the 'scroll-snap-padding' and 'scroll-snap-margin' are consistent with regular 'padding' and 'margin'.
> So those will have to stay physical by default. But we're also planning to add logical syntax options for the 'margin' and 'padding' shorthands in the logical properties module, in which case 'scroll-snap-margin/padding'
> should also accept such syntax. So ultimately, both coordinate systems will be expressible in these properties.
>    https://drafts.csswg.org/css-logical-props/#logical-shorthand-keyword

Cool, that helps.  Definitely agree it will be good to ensure both coordinate systems are expressible.  Could this keyword also be used for scroll-snap-align as a way to enable both?

Thanks,
-Matt
Received on Wednesday, 20 January 2016 14:56:15 UTC

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