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Re: [css-snappoints][css-scroll-snap] Indirect scrolling

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 6 Apr 2016 16:15:20 -0700
Message-ID: <CAAWBYDBQ3jrXWM-4x7X1KmDMhdD3eUzqjqTcsoH+o+VzrMi6=Q@mail.gmail.com>
To: Florian Rivoal <florian@rivoal.net>
Cc: www-style list <www-style@w3.org>
On Wed, Apr 6, 2016 at 1:38 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
> On Sat, Jan 30, 2016 at 12:25 AM, Florian Rivoal <florian@rivoal.net> wrote:
>> The css-scroll-snap spec in section 7 talk esxplicitly about 3 kinds of scrolling, and implicitly about a fourth. The explicit 3 being:
>> - explicit scrolling (e.g. grab the scrollbar thumb)
>> - inertial scrolling
>> - semantic scrolling (down arrow, page down, etc)
>>
>> The other type it is talking about in section 7.3 without naming it is the kind of scrolling that happens when a page is navigated to a fragment that defines a target element.
>>
>> I think there are more instances of this kind of scrolling, which I'm going to call indirect scrolling, where the user is doing an action that isn't itself a scroll, but triggers one. Here are the ones I can think of:
>> - navigate to a fragment (as mentioned above)
>> - Focusing an element (using js, or by pressing tab, or by using spatial navigation)
>> - Moving the insertion caret in an editable element
>> - inserting/deleting/replacing content in an editable element
>>
>> In all cases, which scroll offset you're supposed to end up at is not explicitly requested by the user, but there is a clear demand scrolling to somewhere that makes the relevant thing visible.
>
> These "indirect" scrolling cases are all just "explicit" scrolls; the
> scrolling element suddenly finds itself with a scroll position that
> might not be a snap point, and no momentum/direction information.  So
> yeah, snapping will happen as normal.
>
> (This is why I need to rephrase the scroll categories to be about
> having a position, or a direction/momentum, or both.  Much much
> clearer that way.

And I've done that now.  The three categories are now explicitly
defined in terms of whether the scroll was done with an intended
direction, an intended end position, or both.  I also renamed
"semantic" scroll to "directional" scroll, as it seems clearer.  I
added a few more examples to the categories from this thread, too.

~TJ
Received on Wednesday, 6 April 2016 23:16:07 UTC

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