593564 - Word spacing didn't increase for synthetic bolding on Apple LiGothic since Fx 4.0b

Status: RESOLVED FIXED

(Core :: Layout: Text and Fonts, defect)

Description

[Irvin (MozTW)]

User-Agent:       Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b4) Gecko/20100818 Firefox/4.0b4
Build Identifier: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b4) Gecko/20100818 Firefox/4.0b4

word spacing didn't increase for chinese character with bold weight.
broke since Firefox 4.0beta.

Seen Compare.png to see the different, the longer grey one is from Fx 3.6.8, the black one is from Fx 4.0b4.

The problem appear since first beta, and because it was especially distinct in gmail (the un-read mail title), thus become a significant problem.

Reproducible: Always

Steps to Reproduce:
1. Open test page
2. The letter spacing between chinese characters doesn't get wider when in bold weight. In the mean time, english characters got wider spacing in the bold one.
Actual Results:  
Seen as Fx4.png

Expected Results:  
Seen as Fx3.png

Comment 1

[Irvin (MozTW)]

Attachment: The test page

Comment 2

[Irvin (MozTW)]

Attachment: Fx 3.6.8 screenshot - correctly rendering

Comment 3

[Irvin (MozTW)]

Attachment: Fx 4.0b4 screenshot - rendering wrong

Comment 4

[Irvin (MozTW)]

Attachment: Overlay two screenshots to show the different

Comment 5

[Irvin (MozTW)]

Please pay attention to the wront result screenshot,
the bold chinese character is bolder, but the font-spacing is as same as the normal weight line,
cause the words harder to read.

Comment 6

[Hsiao-Ting Yu (Littlebtc)]

In my opinion, this should be a word spacing problem for all synthetic bolding fonts. The spacing was changed since 1.9.3a1.

Is this possible to be a regression from Core Text Implementation? (Bug 389074)

Comment 7

[Hsiao-Ting Yu (Littlebtc)]

Attachment: Bug 464642 testcase, revisited

Though the original problem from Bug 464642 seems to be accidentally fixed, note the word spacing is narrower in 2.0 than 1.9.2.

Comment 8

[philippe (part-time)]

Fwiw, I don't see any difference between Gecko 1.9.2 / Fx 3.6.8 and Gecko 2.0 / Fx 4.
This is on 10.6.

Safari 5 also shows the same spacing between the characters.

Comment 9

[Irvin (MozTW)]

(In reply to comment #8)
> Fwiw, I don't see any difference between Gecko 1.9.2 / Fx 3.6.8 and Gecko 2.0 /
> Fx 4.
> This is on 10.6.
> 
> Safari 5 also shows the same spacing between the characters.

It is related to the default font what our localization used.
In zh-tw locale version of Fx4, the default font is Apple LiGothic (been used since Fx3), it's synthetic bolding fonts, and had the problem.
If the default font is not Apple LiGothic, OS X 10.6 will use Heiti-TC (default trad. chinese font for 10.6), an multi-weight font to present Trad. Chinese character, thus prevent for the problem.

Comment 10

[philippe (part-time)]

Attachment: test case 2

Ah, now I see the issue. Your test case uses lang="en" on the root element. Hence the behaviour on my side.

In this testcase I added a lang="zh-tw" attibute to the UL. This is indeed different from Gecko 1.9.2.

Comment 11

[Jonathan Kew [:jfkthame]]

The issue can also be demonstrated with a simple testcase using a font such as Apple Casual, which only has a single face:

data:text/html,<p style="font-family:Casual">Hello world<br/><b>Hello world</b>

FF3.6 shows increased spacing for the bold text, while current trunk (4.0 beta) does not.

Comment 12

[Jonathan Kew [:jfkthame]]

Attachment: account for synthetic bold when constructing textrun

Comment 13

[Jonathan Kew [:jfkthame]]

Comment on attachment 472990 [details] [diff] [review]
account for synthetic bold when constructing textrun

Requesting approval to land on trunk for FF4.

This is a regression from FF3.6 and earlier, resulting from a detail that was missed during restructuring text & font code and adopting new shaping backends. The patch simply restores the missing fragment of code so as to give us the proper behavior again.

Comment 14

[Joe Drew (not getting mail)]

Comment on attachment 472990 [details] [diff] [review]
account for synthetic bold when constructing textrun

Would love a test for this.

Comment 15

[Jonathan Kew [:jfkthame]]

Pushed to mozilla-central:
http://hg.mozilla.org/mozilla-central/rev/86a5a8b77d10 (patch)
http://hg.mozilla.org/mozilla-central/rev/30e1991eb11d (reftest)