Combining character doesn't work right in "Segoe UI" font




Layout: Text
6 years ago
6 years ago


(Reporter: Brett Zamir, Assigned: jfkthame)


Firefox Tracking Flags

(Not tracked)



(2 attachments)



6 years ago
User-Agent:       Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Build Identifier: 

I'm not sure whether this is some other issue, but when I try to do an alert using a combining diacritical mark, it looks off, but when added into the page, it looks fine.

Reproducible: Always

Steps to Reproduce:
1. Add a character with a combining mark into an HTML page: À
2. Add a script into the same page to alert the same character:
<script type="text/javascript">
alert('A\u0300'); // The diacritic appears to the top left of the character instead of the top

Actual Results:  
The characters appear differently, with the alerted character having the diacritic askew.

Expected Results:  
See the combining character seamlessly integrated into the base character.


6 years ago
Component: General → Layout
QA Contact: general → layout
This worksforme (on Mac).

Are you sure this isn't just an issue of the web page and the alert using different fonts and the font for the latter (or our handling of it) being broken in your case?

Comment 2

6 years ago
Yes, that may well be. I'm sorry I don't know how to confirm, just know that the default alert font isn't working--not sure that's something u can do anything about or not.
Hm.  What hapens if you style your HTML with "font-family: sans-serif"?

Comment 4

6 years ago
HTML is still ok (and alert still not good). I forgot though that I was testing with a XUL-based HTML editor, and oddly, it is only in that environment that it appears incorrectly---in regular HTML loaded inside a regular browser tab, it shows correctly.
Does the alert you get in the editor look the same as the regular HTML one?  Or is it a separate dialog instead of a tab-modal box?
What happens in HTML styled with "font: menu"?

Comment 7

6 years ago
The alert in the editor says "[JavaScript application]" in the titlebar and its text is conveniently copy-pasteable as in Firefox 3.6 (unlike Firefox 4 now).

 * {font:menu} indeed makes the HTML messed up like the alert (whether applied in a tab or the editor).
OK, yeah.  In the editor you're getting a modal dialog alert, not a tab-modal alert.  And they use different font styles.

Sounds like something is up with our interaction with your "menu" font.  Any idea what font that is?  ;)
Component: Layout → Layout: Text
QA Contact: layout → layout.fonts-and-text

Comment 9

6 years ago
Ok, the "winner" is: "Segoe UI" (Windows 7)
Summary: Combining character in alerts → Combining character doesn't work right in "Segoe UI" font

Comment 10

6 years ago
Ugh... I suspect this is a regression from bug 635639. We may have to try and make the patch there more selective in its effects.
Blocks: 635639
Ever confirmed: true

Comment 11

6 years ago
Created attachment 530252 [details] [diff] [review]
patch, fix handling of non-spacing marks in Segoe UI

The problem here is that the patch for bug 635639 was not quite right (although simply reverting it wouldn't fix things, as that leaves a gap where the diacritic occurs due to its non-zero advance).

In hb_ot_layout_position_finish(), it was incorrect to touch the diacritic's x_offset value, because at this stage GPOS::position_finish() has not yet been called. So all we need to do here is zero the advance width, and then let position_finish() do the proper attachment.
Assignee: nobody → jfkthame
Attachment #530252 - Flags: review?(jdaggett)

Comment 12

6 years ago
Created attachment 530268 [details] [diff] [review]
reftest for diacritic in Segoe UI
Attachment #530268 - Flags: review?(jdaggett)


6 years ago
Attachment #530252 - Flags: review?(jdaggett) → review+

Comment 13

6 years ago
Comment on attachment 530268 [details] [diff] [review]
reftest for diacritic in Segoe UI

Might be nice to have a font that simply replicates the problem found in Segoe UI so that we would catch this on all platforms.  But I'll let you judge whether that's worth the effort or not.
Attachment #530268 - Flags: review?(jdaggett) → review+

Comment 14

6 years ago (patch) (testcase)

We could create a custom font that replicates the problem, but I don't see it as a high priority right now; as long as we're running tests on Win7, at least, we'll know if we regress this (e.g. when taking a harfbuzz update). If we happen to run across a free font that exhibits the same issue, we could add that to the testcase.
Last Resolved: 6 years ago
Resolution: --- → FIXED
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