623495 - Turn on harfbuzz shaper by default for Hebrew on OS X

Status: RESOLVED FIXED

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

Description

[Simon Montagu :smontagu]

Rendering of Hebrew with harbuzz turned on (gfx.font_rendering.harfbuzz.level set to 3) gives much better results for placement of diacritics and cantillation marks in fonts with good open type tables, and is no worse than CoreText in other fonts.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: patch, revise prefs for dispatching scripts to shaping backends

To handle this, it seems like a good time to revise how script-to-shaper dispatching is handled. Instead of a simple "hierarchy" of script complexity, let's use a collection of bit flags that allow the various kinds of shaper to be enabled or disabled independently. This makes it easy to split out Hebrew from the other scripts. We may also find, as harfbuzz shapers develop, that we want to switch on shaping for Hangul, Mongolian, and Indic at different times, and it's not clear which order these will happen, so the old "shaping level" model would potentially need to be repeatedly modified; bit flags give us more flexibility.

Comment 2

[Jonathan Kew [:jfkthame]]

Attachment: patch, revise prefs for dispatching scripts to shaping backends

(Sorry for the bugspam, forgot to do this earlier before posting the patch.)
Updated to consolidate the script-shaping test into gfxPlatform, rather than duplicating it in the gfxFont subclasses.

Comment 3

[Simon Montagu :smontagu]

After the fix for bug 635639 is checked in, can we extend this to all platforms, or are there other problems with older Hebrew fonts in harfbuzz?

Comment 4

[Jonathan Kew [:jfkthame]]

Pushed this to the cedar branch:
http://hg.mozilla.org/projects/cedar/rev/e1167451033f

Comment 5

[Jonathan Kew [:jfkthame]]

(In reply to comment #3)
> After the fix for bug 635639 is checked in, can we extend this to all
> platforms, or are there other problems with older Hebrew fonts in harfbuzz?

We can probably do this, but it'd be good to test a variety of Hebrew fonts on Windows and Linux before actually making the change. I'd suggest we track that in a separate bug.

Comment 6

[(no longer active)]

http://hg.mozilla.org/mozilla-central/rev/e1167451033f