1254275 - Scroll snapping on OS X touchpads doesn't snap if the fingers are lifted without any momentum.

Status: VERIFIED FIXED

(Core :: Panning and Zooming, defect)

Description

[Markus Stange [:mstange]]

STR:
 1. Be on OS X with a touchpad or a magic mouse.
 2. Load http://jsbin.com/pikusa/edit?html,css,output
 3. Over the cat picture, scroll to the right until you're halfway between two cats, pause, and lift your fingers.

Now the scroll box stays in the in-between state and doesn't snap.

Snapping with momentum works fine.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

I can repro on aurora as well.

Comment 2

[Markus Stange [:mstange]]

Attachment: MozReview Request: Bug 1254275 - Inspect the event queue to find out whether momentum events are following. r?kats

Review commit: https://reviewboard.mozilla.org/r/41621/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/41621/

Comment 3

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8733175 [details]
MozReview Request: Bug 1254275 - Inspect the event queue to find out whether momentum events are following. r?kats

https://reviewboard.mozilla.org/r/41621/#review38153

::: gfx/layers/apz/src/AsyncPanZoomController.cpp:2000
(Diff revision 1)
>  
>    SetState(NOTHING);
>    RequestContentRepaint();
>  
> +  if (!aEvent.mFollowedByMomentum) {
> +    RequestSnapToDestination();

It's probably better to call RequestSnap() here, rather than RequestSnapToDestination(), since we aren't going to be doing an animation, and there's no need to compute the predicted destination.

Comment 4

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/dc4afd0b7626

Comment 5

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/dc4afd0b7626

Comment 6

[Kartikaya Gupta (email:[e-mail])]

Uplift to 47?

Comment 7

[Markus Stange [:mstange]]

Comment on attachment 8733175 [details]
MozReview Request: Bug 1254275 - Inspect the event queue to find out whether momentum events are following. r?kats

Approval Request Comment
[Feature/regressing bug #]: APZ and possibly bug 1235994
[User impact if declined]: Unreliable scroll snapping with Mac touchpads
[Describe test coverage new/current, TreeHerder]: no coverage for snapping in response to touchpad events
[Risks and why]: low
[String/UUID change made/needed]: none

Comment 8

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Comment on attachment 8733175 [details]
MozReview Request: Bug 1254275 - Inspect the event queue to find out whether momentum events are following. r?kats

APZ related, Aurora47+

Comment 9

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/releases/mozilla-aurora/rev/4265845fa347

Comment 10

[Petruta Horea [:phorea], PTO until 8/22/25]

Verified as fixed un\sing Firefox 47 beta 6 and latest Aurora 48.0a2 under Mac OS X 10.9.5 retina with touchpad.