[Webkit-unassigned] [Bug 182521] REGRESSION (iOS 11.3 beta): touchmove preventDefault() no longer respected

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=182521

--- Comment #9 from Rick Byers <rbyers at chromium.org> ---
Some data from Chrome to help with the compat decision making here:

touch-action is used on ~18% of all page views: https://www.chromestatus.com/metrics/css/timeline/popularity/421

Of course many of these are "touch-action: manipulation", which does work fine in WebKit.

Looking at some internal metrics (TouchAction.EffectiveTouchAction), I see that touch-actions not supported in WebKit are used as follows (as a fraction of all touch gestures):
  none: 1%
  pan-y: 2.4%
  pan-x pan-y: 0.5%

This means that there's an upper bound of about 4% of all touches which could be broken by ignoring preventDefault without honoring these touch-action values.  Of course not all of these will be for listeners on the document.  We have separate metrics (Event.Touch.TargetAndDispatchResult) which show that about 35% of touch event dispatches occur on "root scroller" handlers (i.e. those impacted by this intervention).  So a reasonable guess would be that roughly 1% of all touches would be broken by this.

But what worries me more is that we've just recently seen usage of passive:false jump from 2% of all page views to 4%:
https://www.chromestatus.com/metrics/feature/timeline/popularity/1418

If iOS 11.3 ships in this current state, I'm concerned we'll see this jump higher - reducing the utility of the passive touch listeners feature.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20180319/5c381b2f/attachment.html>