Bug 192320

Summary:

REGRESSION (r238090): position:fixed sidebar on https://www.w3.org/TR/SVG2/coords.html does not stay fixed

Product:

WebKit

Reporter:

Simon Fraser (smfr) <simon.fraser>

Component:

Layout and Rendering

Assignee:

Simon Fraser (smfr) <simon.fraser>

Status:

RESOLVED FIXED

Severity:

Normal

CC:

bfulgham, commit-queue, ryanhaddad, simon.fraser, webkit-bug-importer, zalan

Priority:

Keywords:

InRadar

Version:

WebKit Nightly Build

Hardware:

Unspecified

OS:

Unspecified

URL:

https://www.w3.org/TR/SVG2/coords.html

Bug Depends on:

192342

Bug Blocks:

Attachments:

Description	Flags
Patch	none
Patch	none

Simon Fraser (smfr)

Reported 2018-12-03 13:31:28 PST

The position:fixed sidebar on https://www.w3.org/TR/SVG2/coords.html doesn't stay fixed; it scrolls, then snaps when you hover.

Attachments
Patch (7.05 KB, patch) 2018-12-03 18:17 PST, Simon Fraser (smfr)	no flags	Details Formatted Diff Diff
Patch (7.05 KB, patch) 2018-12-03 19:18 PST, Simon Fraser (smfr)	no flags	Details Formatted Diff Diff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.

Radar WebKit Bug Importer

Comment 1 2018-12-03 13:33:34 PST

<rdar://problem/46429833>

Simon Fraser (smfr)

Comment 2 2018-12-03 15:03:50 PST

The page is using main thread scrolling (because of fixed backgrounds), and the compositing update pass is failing to update the positions of fixed elements.

Simon Fraser (smfr)

Comment 3 2018-12-03 18:17:21 PST

Created attachment 356443 [details] Patch

Simon Fraser (smfr)

Comment 4 2018-12-03 19:18:50 PST

Created attachment 356448 [details] Patch

zalan

Comment 5 2018-12-03 19:22:13 PST

Comment on attachment 356448 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=356448&action=review > Source/WebCore/rendering/RenderLayerCompositor.cpp:669 > + bool isPageScroll = !updateRoot || updateRoot == &rootRenderLayer(); auto

WebKit Commit Bot

Comment 6 2018-12-03 20:03:56 PST

Comment on attachment 356448 [details] Patch Clearing flags on attachment: 356448 Committed r238840: <https://trac.webkit.org/changeset/238840>

WebKit Commit Bot

Comment 7 2018-12-03 20:03:58 PST

All reviewed patches have been landed. Closing bug.

Ryan Haddad

Comment 8 2018-12-04 09:14:18 PST

The layout test added with this change is frequently failing, as EWS indicated here: https://webkit-queues.webkit.org/patch/356448/ios-sim-ews https://webkit-queues.webkit.org/patch/356448/mac-ews https://webkit-queues.webkit.org/patch/356448/mac-debug-ews Link to image diff showing the scrollbar appearing in an unexpected location: https://build.webkit.org/results/Apple%20Sierra%20Release%20WK1%20(Tests)/r238851%20(14458)/compositing/fixed-with-main-thread-scrolling-diffs.html

Ryan Haddad

Comment 9 2018-12-04 09:17:26 PST

Reverted r238840 for reason: The layout test added with this change is frequently failing. Committed r238855: <https://trac.webkit.org/changeset/238855>

Ryan Haddad

Comment 10 2018-12-04 17:14:30 PST

This was re-landed in https://trac.webkit.org/changeset/238876/webkit The test is still failing on the bots: https://build.webkit.org/results/Apple%20Sierra%20Release%20WK1%20(Tests)/r238877%20(14473)/results.html http://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=compositing%2Ffixed-with-main-thread-scrolling.html

Simon Fraser (smfr)

Comment 11 2018-12-04 18:19:17 PST

Relanded in https://trac.webkit.org/r238876 Attempted to de-flake the test in https://trac.webkit.org/r238883.

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