Bug 134283 – Implement CSS Scroll Snap Points Spec

• Component: WebCore Misc.
• Status: RESOLVED FIXED

[Wenson Hsieh]

Radar link: <rdar://problem/17283505>

Implement CSS snap points according to the (not yet final) W3C spec here: http://dev.w3.org/csswg/css-snappoints/
See bug-issues for more details.

[Wenson Hsieh]

<rdar://problem/17283505>

[Wenson Hsieh]

(In reply to comment #0)
> Radar link: <rdar://problem/17283505>
> 
> Implement CSS snap points according to the (not yet final) W3C spec here: http://dev.w3.org/csswg/css-snappoints/
> See bug-issues for more details.

^^^ that's *sub*-issues, not bug-issues

[Wenson Hsieh]

First sub-issue: https://bugs.webkit.org/show_bug.cgi?id=134301

[Wenson Hsieh]

Second subissue: exposing trackpad scrolling phases https://bugs.webkit.org/show_bug.cgi?id=134283

[Wenson Hsieh]

(In reply to comment #4)

[Correction] Second sub-issue is https://bugs.webkit.org/show_bug.cgi?id=135195, not this page.

[Wenson Hsieh]

Created attachment 236686 [details]
Basic scroll-snapping examples

Contains two web pages that demonstrate basic examples of snap scrolling. iphone.html shows a vertically scrolling overflow div that fills the entire window and has a snap point at the top of every image. itunes.html shows three divs: the first scrolls horizontally with images snapping to the left edge; the second also scrolls horizontally, but has images snapping to the center; the last example shows 2D scrolling, with snap points on both axes at every image.

[Wenson Hsieh]

List of known issues with CSS snap points implementation:

- Rename the CSS_SCROLL_SNAP feature flag to CSS_SNAP_POINTS.

- Make WKWebView set deceleration to fast when didCommitLayerTree is called, rather than when scrolling will begin dragging.

- Account for insets on the iOS mainframe.

- Improve Mac snapping animations (also, improve their performance)

- In the spec, the repeat value begins counting from the "last point." We need to clarify what this means -- currently, the implementation starts counting from the furthest point, which would not be correct if the list of snap points is not sorted and our interpretation of "last point" is the last point specified by the user.

- Clarify what the expected behavior is when a snap point moves, disappears, or is added to the snap scrolling container.

Also see:

https://bugs.webkit.org/show_bug.cgi?id=135964
https://bugs.webkit.org/show_bug.cgi?id=135994
https://bugs.webkit.org/show_bug.cgi?id=135997
https://bugs.webkit.org/show_bug.cgi?id=136005

[Simon Fraser (smfr)]

Can we close this now?

[Martin Robinson]

Removing dependency on 203684 as it is now part of the metabug at: issue 221461.

[Martin Robinson]

I think it makes sense to close this issue. We have the metabug at https://bugs.webkit.org/show_bug.cgi?id=218115 to track remaining implementation / compatability issues and then there are also quite a few remaining issues related to scroll snap behavior in Bugzilla in general.