Bug 235937

Summary: [LFC][IFC] Using Fontcascade::spaceWidth to subtract the trailing space width may result in incorrect layout
Product: WebKit Reporter: alan <zalan>
Component: Layout and RenderingAssignee: alan <zalan>
Status: RESOLVED FIXED    
Severity: Normal CC: bfulgham, commit-queue, koivisto, mjs, mmaxfield, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=235995
Bug Depends on: 235998    
Bug Blocks:    
Attachments:
Description Flags
Patch
none
Patch
none
Patch
none
Patch
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Patch ews-feeder: commit-queue-

alan
Reported 2022-01-31 20:23:58 PST
when the primary font does not have space glyph.
Attachments
Patch (5.14 KB, patch)
2022-01-31 20:28 PST, alan 		no flags
DetailsFormatted DiffDiff
Patch (5.32 KB, patch)
2022-02-01 08:16 PST, alan 		no flags
DetailsFormatted DiffDiff
Patch (5.16 KB, patch)
2022-02-01 09:06 PST, alan 		no flags
DetailsFormatted DiffDiff
Patch (52.97 KB, patch)
2022-02-01 13:04 PST, alan 		no flags
DetailsFormatted DiffDiff
Patch (52.58 KB, patch)
2022-02-01 20:18 PST, alan 		ews-feeder: commit-queue-
DetailsFormatted DiffDiff
Show Obsolete (4) View All Add attachment proposed patch, testcase, etc.
alan
Comment 1 2022-01-31 20:24:16 PST
<rdar://88059633>
alan
Comment 2 2022-01-31 20:28:09 PST
Created attachment 450492 [details] Patch
alan
Comment 3 2022-02-01 08:16:43 PST
Created attachment 450529 [details] Patch
alan
Comment 4 2022-02-01 09:06:55 PST
Created attachment 450538 [details] Patch
Maciej Stachowiak
Comment 5 2022-02-01 12:10:21 PST
<rdar://88059633>
alan
Comment 6 2022-02-01 13:04:45 PST
Created attachment 450559 [details] Patch
EWS
Comment 7 2022-02-01 14:53:21 PST
Committed r288914 (246654@main): <https://commits.webkit.org/246654@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 450559 [details].
WebKit Commit Bot
Comment 8 2022-02-01 20:02:17 PST
Re-opened since this is blocked by bug 235998
alan
Comment 9 2022-02-01 20:18:05 PST
Created attachment 450605 [details] Patch
alan
Comment 10 2022-02-01 20:22:50 PST
null terminator? where we're going we don't need null terminator.
EWS
Comment 11 2022-02-01 21:52:10 PST
Committed r288944 (246674@main): <https://commits.webkit.org/246674@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 450605 [details].
Myles C. Maxfield
Comment 12 2022-02-01 22:20:40 PST
Comment on attachment 450605 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=450605&action=review > Source/WebCore/layout/formattingContexts/inline/text/TextUtil.cpp:94 > + return fontCascade.width(TextRun { String { &space, 1 } }); There are no performance problems with this?
alan
Comment 13 2022-02-02 06:37:55 PST
(In reply to Myles C. Maxfield from comment #12) > Comment on attachment 450605 [details] > Patch > > View in context: > https://bugs.webkit.org/attachment.cgi?id=450605&action=review > > > Source/WebCore/layout/formattingContexts/inline/text/TextUtil.cpp:94 > > + return fontCascade.width(TextRun { String { &space, 1 } }); > > There are no performance problems with this? I had run our classic PerformanceTests/Layout/line-layout-simple.html microbenchmark locally before landing this and it showed about 0.5% regression. I also tested it with a slightly different version of the patch: const auto& spaceGlyphData = fontCascade.glyphDataForCharacter(space, false); return (!spaceGlyphData.font ? fontCascade.spaceWidth() : spaceGlyphData.font>widthForGlyph(spaceGlyphData.glyph)) + fontCascade.letterSpacing(); and it came back with the same numbers.
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