Bug 235937 - [LFC][IFC] Using Fontcascade::spaceWidth to subtract the trailing space width may result in incorrect layout
Summary: [LFC][IFC] Using Fontcascade::spaceWidth to subtract the trailing space width...
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: WebKit Nightly Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: zalan
URL:
Keywords: InRadar
Depends on: 235998
Blocks:
  Show dependency tree / graph
 
Reported: 2022-01-31 20:23 PST by zalan
Modified: 2022-02-02 06:37 PST (History)
8 users (show)

See Also:

Attachments
Patch (5.14 KB, patch)
2022-01-31 20:28 PST, zalan 		no flags Details | Formatted Diff | Diff
Patch (5.32 KB, patch)
2022-02-01 08:16 PST, zalan 		no flags Details | Formatted Diff | Diff
Patch (5.16 KB, patch)
2022-02-01 09:06 PST, zalan 		no flags Details | Formatted Diff | Diff
Patch (52.97 KB, patch)
2022-02-01 13:04 PST, zalan 		no flags Details | Formatted Diff | Diff
Patch (52.58 KB, patch)
2022-02-01 20:18 PST, zalan 		ews-feeder: commit-queue-
Details | Formatted Diff | Diff
Show Obsolete (4) View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description zalan 2022-01-31 20:23:58 PST 
when the primary font does not have space glyph.
Comment 1 zalan 2022-01-31 20:24:16 PST 
<rdar://88059633>
Comment 2 zalan 2022-01-31 20:28:09 PST 
Created attachment 450492 [details]
Patch
Comment 3 zalan 2022-02-01 08:16:43 PST 
Created attachment 450529 [details]
Patch
Comment 4 zalan 2022-02-01 09:06:55 PST 
Created attachment 450538 [details]
Patch
Comment 5 Maciej Stachowiak 2022-02-01 12:10:21 PST 
<rdar://88059633>
Comment 6 zalan 2022-02-01 13:04:45 PST 
Created attachment 450559 [details]
Patch
Comment 7 EWS 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].
Comment 8 WebKit Commit Bot 2022-02-01 20:02:17 PST 
Re-opened since this is blocked by bug 235998
Comment 9 zalan 2022-02-01 20:18:05 PST 
Created attachment 450605 [details]
Patch
Comment 10 zalan 2022-02-01 20:22:50 PST 
null terminator? where we're going we don't need null terminator.
Comment 11 EWS 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].
Comment 12 Myles C. Maxfield 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?
Comment 13 zalan 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.