[csswg-drafts] [css-scroll-snap-1] Clarify passing by requirement of scroll-snap-stop for different category of scrolling

majido has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-scroll-snap-1] Clarify passing by requirement of scroll-snap-stop for different category of scrolling ==
Definition of `scroll-snap-stop` refers to the concept of **passing by a snap position during the execution of a scrolling operation** however the specification does not define what exactly considered *passing by* for different scrolling categories. I suspect, for best UX we may want to have a different definition of passing by for different scroll categories.

For examples for scrolling operations with only intended end position what is considered passed by?
 1. Any element in the "corridor" that the snapport defines as it moves through the scrollable overflow region is considered passed by.
 2. Only elements in the snapport after scroll position is at the natural end-point. 

Definition 1 seems like a reasonable definition but I think we actually want definition 2 for scrolls with only intended end. Not only it matches the definition used for visibility requirement for such scrolls but also it provides a better UX IMHO. For examples consider a page that has a mandatory snap stop in the middle and the user pans all the way to the bottom of the page and releases their finger (or tabs to get to the only focused element at page bottom). First definition forces them to go back to the middle of the page as we cannot pass that snap point which I don't think is the intended/expected behavior.  

For scrolls with only intended direction. I think the correct definition is actually the definition 1.

Also according to earlier IRC discussion[1], for scrolls with intended direction and end position we want definition 2. Because an inertial scroll is expected to be able to pass a mandatory stop.

[1] 
> 11:47 AM \<fantasai\> majidvp: mandatory vs proximity isn't about stopping, it's about whether the scroll position must be at a snap position or not
11:47 AM majidvp: You can scroll past a mandatory stop on inertia. You just can't stop on a position that isn't snapped
11:48 AM majidvp: It's a different concept, whether you pass through the stop on inertia or not vs whether when you "land" you are pushed to the nearest snap position or not

 

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/1552 using your GitHub account

Received on Thursday, 22 June 2017 17:14:48 UTC