Bug 251753 - Disconnected Arabic glyphs for embolden webfont
Summary: Disconnected Arabic glyphs for embolden webfont
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Text (show other bugs)
Version: Safari Technology Preview
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: BrowserCompat, InRadar
Depends on:
Blocks:
 
Reported: 2023-02-05 00:17 PST by Ebrahim Byagowi
Modified: 2023-02-13 00:58 PST (History)
4 users (show)

See Also:

Attachments
Disconnected Arabic glyphs (399.58 KB, image/png)
2023-02-05 00:17 PST, Ebrahim Byagowi 		no flags Details
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Description Ebrahim Byagowi 2023-02-05 00:17:58 PST 
Created attachment 464847 [details]
Disconnected Arabic glyphs

Happens in both tip of tree WebKit (6c4c9810) and Safari 16.2

1. Open https://datehijri.com/ (or its archive here https://web.archive.org/web/20230121054820/https://datehijri.com/ )
2. Pinch to zoom on the green colored text below

Actual:
It has disconnected Arabic glyphs.

Expected:
Like Firefox and Chrome, not disconnected Arabic glyphs
Comment 1 Ebrahim Byagowi 2023-02-05 13:22:53 PST 
Guess this is rather a CoreText bug than WebKit
Comment 2 zalan 2023-02-05 15:51:05 PST 
I noticed that some of the text (e.g. لتاريخ الميلادي:) was split into multiple runs and we painted them individually. Sometimes (incorrect) mismatching rounding directions could manifest in such subpixel gaps. However, after force-merging them all (so that لتاريخ الميلادي comes out as one TextRun) I was still able to see those tiny gaps, so this very well be a CoreText bug as you said. Myles, what do you think?
Comment 3 Radar WebKit Bug Importer 2023-02-12 00:18:19 PST 
<rdar://problem/105352894>