Bug 169800

Summary:

After a programmatic scroll in a scroll snap container, the scroll offset jumps to the last reached snap offset

Product:

WebKit

Reporter:

Malte Ubl <malte>

Component:

CSS

Assignee:

Wenson Hsieh <wenson_hsieh>

Status:

RESOLVED WORKSFORME

Severity:

Blocker

CC:

jonlee, mrobinson, simon.fraser, sriramkrish85, webkit-bug-importer, wenson_hsieh

Priority:

Keywords:

InRadar

Version:

Safari Technology Preview

Hardware:

iPhone / iPad

OS:

Unspecified

Attachments:

Description	Flags
Reduced test case adapted from <http://output.jsbin.com/fiwiqo>	none

Malte Ubl

Reported 2017-03-16 17:55:18 PDT

I'm sorry that we do not currently have a reduced repro case, but we thought you might want to know that CSS snap points are broken in Safari in current iOS 10.3 beta 2. More details here https://github.com/ampproject/amphtml/issues/7670 The bug has a few repro URLs. This affects a large subset of AMP pages (likely a few 100 million). We will revert to non-snap points behavior, but this will represent a signficiant regression in UX.

Attachments
Reduced test case adapted from <http://output.jsbin.com/fiwiqo> (2.66 KB, text/html) 2017-04-05 14:57 PDT, Wenson Hsieh	no flags	Details
View All Add attachment proposed patch, testcase, etc.

Malte Ubl

Comment 1 2017-03-16 18:18:58 PDT

Updated to reflect that this is still broken in beta 6.

Sriram Krishnan

Comment 2 2017-03-16 18:47:24 PDT

Here is the URL to reproduce what Malte described below http://amphtml-nightly.herokuapp.com/test/manual/amp-slidescroll.amp.html Videos: Working slides on IOS 10.2- https://www.youtube.com/watch?v=DkI5U9Sqlm4 Broken slides on IOS 10.3 beta (test on beta 7) - https://www.youtube.com/watch?v=r6jZILTvt5E

Simon Fraser (smfr)

Comment 3 2017-03-16 21:41:08 PDT

The syntax changed to match the latest spec: https://drafts.csswg.org/css-scroll-snap-1/

Sriram Krishnan

Comment 4 2017-03-16 23:36:39 PDT

@smfr - is there a date when this would come out of beta?

Sriram Krishnan

Comment 5 2017-03-21 18:20:14 PDT

Ok - Now i got clarity into what the real issue is. This is because of snap points This is not because of the syntax change , the old syntax still works fine on the beta. The only issue is when we set scrollLeft on the container via JS, the browser resets it back to the last known snap position set via css snapping. the right behavior would be to snap to the closest snap point. Here is my JS BIN http://jsbin.com/fiwiqo/61/edit?html,css,js,output And the video demonstrating what is wrong. https://youtu.be/r5P8d-k1Q1Y

Sriram Krishnan

Comment 6 2017-03-24 22:14:23 PDT

@Wenson Hsieh, any updates on this? will this be fixed before the beta launches?

Wenson Hsieh

Comment 7 2017-03-25 01:49:58 PDT

(In reply to Sriram Krishnan from comment #6) > @Wenson Hsieh, any updates on this? will this be fixed before the beta > launches? Unfortunately, I cannot comment on what changes will make it into future releases. However, I will make it a priority to investigate and fix this problem on ToT.

Wenson Hsieh

Comment 8 2017-03-25 02:08:22 PDT

<rdar://problem/31257989>

Sriram Krishnan

Comment 9 2017-04-04 13:17:01 PDT

Any update on when this would be fixed. As Malte mentioned it affects a few 100 million (AMP) pages, it would be great to get this fixed at the earliest possible!

Jon Lee

Comment 10 2017-04-04 13:56:19 PDT

Thanks. Unfortunately, we cannot discuss release dates, but understand that this is a very important bug for AMP.

Wenson Hsieh

Comment 11 2017-04-05 14:57:23 PDT

Created attachment 306322 [details] Reduced test case adapted from <http://output.jsbin.com/fiwiqo>

Sriram Krishnan

Comment 12 2017-05-31 15:44:57 PDT

I believe this was solved in https://bugs.webkit.org/show_bug.cgi?id=170560 - can some one correct me if i am wrong? @Wenson Hsieh

Martin Robinson

Comment 13 2021-06-03 03:22:57 PDT

I can no longer reproduce this. I think it's fixed.

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