Re: [ft-devel] ttfautohint - render issue with composites on OSX CHrome

From:

신정식, 申政湜

Subject:

Date:

Wed, 27 Mar 2013 11:00:24 -0700

Hi Vernon,

Thank you for the report.

Chrome on Mac OS X does not use FreeType, but as you said, it's possible that the way composite glyphs are handled by ttautohint can get in the way of rendering those glyphs by Chrome on Mac OS X for some reason. One possibility is that Skia (2D graphics library used across platforms by Chrome) chokes on some of those glyphs. In the past, we've observed something similar to what you observed (part wiped out, missing stems, etc) for some fonts on Mac, Windows and Linux and all of them were attributed to Skia.

Having said that, I've tried your web page with Chrome 26.0.1410.5 dev channel and I don't see any problem ('i', 'ff' and 'f'). I may have missed what you see and I'm attaching a screenshot for you to take a look at. I also tried Chrome canary (nightly build) 27.0.1454.0 and didn't see any problem, either.

It's possible that Skia had a problem with fonts auto-hinted by ttautohint, but the issue has been fixed since. What version of Chrome do you have?

Jungshik

2013/3/26 Vernon Adams <address@hidden>

There appears to be a OSX Chrome render issue with specific glyphs auto instructed with ttfautohint.

Please see http://www.georgduffner.at/ebgaramond/
On OSX Chrome all characters that are composite substitute glyphs are being rendered badly (part wiped out, missing stems etc)
The site linked to above is using different gsub tables for substituting the 'f' with a 'longs' , 'i' with 'dotless i' + 'dot accent', 'f', 'f' pairs with 'ff' ligature etc.

The fonts are autohinted with the 'hint composites' option selected, and the effected glyphs contain the ttfautohint dummy glyph used when autohinting composites.

Please note it is only Chrome on OSX that shows this messed up rendering, other browsers on OSX render the glyphs fine.

-v
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