Bug 139245

Summary: Programmatic scrolling and content changes are not always synchronized
Product: WebKit Reporter: Simon Fraser (smfr) <simon.fraser>
Component: Layout and RenderingAssignee: Simon Fraser (smfr) <simon.fraser>
Status: RESOLVED FIXED    
Severity: Normal CC: andersca, cmarcelo, commit-queue, jamesr, luiz, simon.fraser, thorton, tonikitoo, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Patch andersca: review+

Simon Fraser (smfr)
Reported 2014-12-03 17:20:56 PST
Content that changes the scroll offset, and changes the style of an element at the same time should be able to make that element appear in a fixed position. However, for some reason WebKit is unable to always synchronize the two, and the element flickers.
Attachments
Patch (9.18 KB, patch)
2014-12-05 17:04 PST, Simon Fraser (smfr) 		andersca: review+
DetailsFormatted DiffDiff
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Simon Fraser (smfr)
Comment 1 2014-12-03 17:21:14 PST
rdar://problem/18833612
Simon Fraser (smfr)
Comment 2 2014-12-05 16:05:44 PST
Even when programmatic scrolling, AsyncScrollingCoordinator::requestScrollPositionUpdate() sends the scroll off to the scrolling thread, which sometime later tells the UI thread that we scrolled in AsyncScrollingCoordinator::scheduleUpdateScrollPositionAfterAsyncScroll(), which (on a timer) hits AsyncScrollingCoordinator::updateScrollPositionAfterAsyncScroll().
Simon Fraser (smfr)
Comment 3 2014-12-05 17:04:50 PST
Created attachment 242685 [details] Patch
Simon Fraser (smfr)
Comment 4 2014-12-05 17:25:04 PST
https://trac.webkit.org/r176899
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