Bug 172855 - REGRESSION(Safari 10): rendering issues with U+20D7 when separated from preceding character by span
Summary: REGRESSION(Safari 10): rendering issues with U+20D7 when separated from prece...
Alias: None
Product: WebKit
Classification: Unclassified
Component: Text (show other bugs)
Version: Safari 10
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
Keywords: InRadar
Depends on:
Reported: 2017-06-02 06:54 PDT by Peter Krautzberger
Modified: 2017-08-21 11:52 PDT (History)
3 users (show)

See Also:

Reproduction (747 bytes, text/html)
2017-08-21 11:46 PDT, Myles C. Maxfield
no flags Details

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Description Peter Krautzberger 2017-06-02 06:54:02 PDT
When U+20D7 (and possibly other combining characters) is separated from the preceding character by a span element, the combination renders badly in Safari 10.

In particular, Safari 10 renders this differently from other browsers (see [2]). 

Safari 10 also renders more test cases badly than Safari 9 did. On the other hand, WebKitGTK+ 2.16.3 has no issues.

* minimal example [1]
* screenshots (archive) [2]
* original context [3]

[1] https://codepen.io/pkra/pen/yXBRxW
[2] https://github.com/mathjax/MathJax/files/1047779/cbt_2358181_2472234.zip
[3] https://github.com/mathjax/MathJax/issues/1709#issuecomment-305648698

Thanks in advance.
Comment 1 Myles C. Maxfield 2017-06-02 11:39:01 PDT
This is a duplicate of https://bugs.webkit.org/show_bug.cgi?id=6148.

*** This bug has been marked as a duplicate of bug 6148 ***
Comment 2 Peter Krautzberger 2017-06-02 12:47:19 PDT
Thanks, Myles.

I can see the connection but it seems this issue might be different enough since

a) there's a regression in Safari 10 compared to 9

b) WebKitGTK+ 2.16.3 does not have a problem

while #6148 is much older and marked as applying to WebKit in general.

Thanks again,
Comment 3 Myles C. Maxfield 2017-06-02 12:57:28 PDT
Reopening due to regression
Comment 4 Radar WebKit Bug Importer 2017-06-02 21:00:10 PDT
Comment 5 David Kilzer (:ddkilzer) 2017-08-09 19:19:00 PDT
See also:  <https://github.com/mathjax/MathJax/issues/1709#issuecomment-305795001>
Comment 6 Myles C. Maxfield 2017-08-21 11:46:17 PDT
Created attachment 318653 [details]
Comment 7 Myles C. Maxfield 2017-08-21 11:52:25 PDT
Until we can do cross-element shaping, if you start an element with a combining mark, you're gonna have a bad time. https://bugs.webkit.org/show_bug.cgi?id=6148 will fix this.

Between Safari 9 and Safari 10, I fixed some bugs about how we account for the initial advance. These fixes are progressions, and should not be reverted. The best bet for us to fix this problem is just to fix the root issue, and not try to figure out which progression caused this bug to occur.