[cairo] text measurement in perf?

[Baz]

Hi,
I'm hoping to tackle some of the issues firefox have with slow text
measurement on the mac[1] this weekend. I've got a fix in mind, but
perf-diff isn't going to notice it - the 'text' perf test renders
parts of the same string repeatedly and won't ask for a lot of glyph
measurements.

I think I want to add a perf test for glyph-extents (rather than
text-extents, since programs using the 'real' font api will do
text-to-glyphs for themselves). I was thinking of taking chunks of of,
eg, 100 glyphs at a time, filling the glyph array with sequential
glyph ids modulo some largish number - so I'm not always hitting the
cache - and not bothering to render the text at all.

Does this sound reasonable? Any better ideas before I head home and code this?

-Baz

[1] http://weblogs.mozillazine.org/roc/archives/2007/05/the_glyph_bound.html