Bug 211374

Summary: REGRESSION(r260571): RequestedScrollPosition doesn't have its scroll change applied to layers anymore
Product: WebKit Reporter: Zan Dobersek <zan>
Component: ScrollingAssignee: Zan Dobersek <zan>
Status: RESOLVED FIXED    
Severity: Normal CC: cgarcia, cmarcelo, ews-watchlist, gyuyoung.kim, koivisto, luiz, noam, ryuan.choi, sergio, simon.fraser, webkit-bug-importer, zeno
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Patch none

Description Zan Dobersek 2020-05-04 03:42:27 PDT 
After r260571, in the Nicosia scrolling mechanisms, scrolling changes applied onto the main-frame scrolling nodes through the RequestedScrollPosition state property change don't have any effect anymore. I assume this problem isn't exhibited on Mac/iOS.
https://trac.webkit.org/changeset/260571/webkit

This leaves the RequestedScrollPosition state changes to have no effect on the positioning of the layers, ergo scrolling via scrollbars or keyboard does not behave correctly.

A call to applyLayerPositionsInternal() at the end of the ScrollingTree::commitTreeState() would for instance restore the correct behavior.
Comment 1 Simon Fraser (smfr) 2020-05-04 09:40:46 PDT 
This is because of me juggling which when layer positions are applied.

Layer positions should be getting applied at the end of the rendering updates; on macOS this happens in Page::finalizeRenderingUpdate().
Comment 2 Zan Dobersek 2020-05-13 05:52:18 PDT 
(In reply to Simon Fraser (smfr) from comment #1)
> This is because of me juggling which when layer positions are applied.
> 
> Layer positions should be getting applied at the end of the rendering
> updates; on macOS this happens in Page::finalizeRenderingUpdate().

That's what's needed, thanks for the tip.
Comment 3 Zan Dobersek 2020-05-13 05:57:58 PDT 
Created attachment 399254 [details]
Patch
Comment 4 Carlos Garcia Campos 2020-05-13 06:00:23 PDT 
Comment on attachment 399254 [details]
Patch

Thanks!
Comment 5 Zan Dobersek 2020-05-13 07:42:48 PDT 
Comment on attachment 399254 [details]
Patch

Clearing flags on attachment: 399254

Committed r261616: <https://trac.webkit.org/changeset/261616>
Comment 6 Zan Dobersek 2020-05-13 07:42:52 PDT 
All reviewed patches have been landed.  Closing bug.
Comment 7 Radar WebKit Bug Importer 2020-05-13 07:43:13 PDT 
<rdar://problem/63183761>