[tor-qa] Font debugging page (TBB 5.0a4)

[David Fifield]

On Thu, Aug 06, 2015 at 01:36:57PM +0200, Moritz Bartl wrote:
> On 08/06/2015 11:43 AM, David Fifield wrote:
> > Oh, very interesting. It seems the difference is only in one code point,
> > in the "cursive" and "fantasy" styles (last two columns): [...]
> > Could you make screenshots of the two renderings? 
> 
> Attached. I don't see any difference between default and cursive.

That's very interesting. In just that one code point, your computer
chooses a sans-serif font for the "fantasy" and "cursive" styles, while
mine chooses a serif font. Probably we would find more examples if we
tested more of Unicode.

I would not have expected a difference like this. It does not come down
to small rendering differences; the browser is simply choosing a
different font. Perhaps there is something non-deterministic about how
Firefox (or Fontconfig) loads its font files. Like, maybe it iterates a
directory in inode order and takes the first match when there is a tie.

Interestingly, even our two "default" screenshots are not
pixel-identical. It looks like it comes down to different hinting
settings. It is especially apparent in the small text at the top. I
attach an animation comparing the two renderings. This is the realm of
#16739.
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