722274 - with-first-letter-1a.html and with-first-letter-1b.html broken on Mac OS X 10.7

Status: NEW

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

Description

[Jonathan Watt [:jwatt]]

Attachment: reftest log of original breakage

Tiny subpixel differences are causing with-first-letter-1a.html and with-first-letter-1b.html to fail for me when run locally on Mac OS X 10.7 (FF built using Xcode 4.2).

I tried adding letter-spacing as suggested in bug 722206 comment 1, but the text layout then breaks because in the tests the letter spacing is applied between the "D" and the Hebrew letter beside it, whereas it's not in the reference. Being unfamiliar with bidi I'm wondering how the markup should be changed to fix that.

Comment 1

[Jonathan Watt [:jwatt]]

I also note that jfkthame changed the letters in these tests to try and work around a similar issue for Windows 7 when running the tests without hardware acceleration.

https://hg.mozilla.org/mozilla-central/rev/557412abf1e8

Comment 2

[Jonathan Kew [:jfkthame]]

(In reply to Jonathan Watt [:jwatt] from comment #0)
> I tried adding letter-spacing as suggested in bug 722206 comment 1, but the
> text layout then breaks because in the tests the letter spacing is applied
> between the "D" and the Hebrew letter beside it, whereas it's not in the
> reference.

Actually, it _is_ applied there in the reference, but it's applied _doubly_ in the tests. (You can tell this more easily if you add a really big letter-spacing value.) I'm inclined to think that is a bug in how letter-spacing is implemented, though I haven't checked whether the spec attempts to define exactly what should happen at directional boundaries.

(In reply to Jonathan Watt [:jwatt] from comment #1)
> I also note that jfkthame changed the letters in these tests to try and work
> around a similar issue for Windows 7 when running the tests without hardware
> acceleration.

Yeah.... total hack, sorry!

Comment 3

[Jonathan Kew [:jfkthame]]

Filed bug 722284 on the brokenness of letter-spacing at bidi boundaries.

As for working around the issue here, you might find that enlarging the text size (e.g. to 40px or so) would avoid the issue; maybe worth pushing something like that to tryserver to see if it's happy?

Comment 4

[Jonathan Watt [:jwatt]]

(In reply to Jonathan Kew (:jfkthame) from comment #2)
> Yeah.... total hack, sorry!

No, no, I was just wondering if either of you might like to change the text back if letter-spacing was working. :)

(In reply to Jonathan Kew (:jfkthame) from comment #3)
> As for working around the issue here, you might find that enlarging the text
> size 

I'm personally happy to wait for a fix for bug 722284, and then try letter-spacing again.