[cairo] weird mac bug in 1.3

Baz brian.ewins at gmail.com
Thu Feb 1 04:21:33 PST 2007

Theres some background here:

Text rendering seems to have regressed in 1.3 on intel mac, in a way
that mainly affects moz-svg for some reason. I have to question
whether what I'm seeing is real here though, because I only switched
to intel last week, and to begin with I had issues with PPC versions
of frameworks, darwinports (which I've blown away and refreshed since)

The bug shows up in the text-pattern test (the only test involving
scaled text). On macs this has been broken forever, waiting for this
to land:
Before the patch, the image surface shows 2 or 3 rows of pixels at the
bottom of the text in that test. After the patch, on PPC, the text is
ok; on Intel, you can see all the letters, but they are all positioned
on top of each other where the c of cairo should be. nquartz is
irrelevant here, since it falls back to the atsui surface code for
this test.

Digging in a little further, I found that the letters are getting very
small x coordinates - something like 3E-315 (the number varies, but is
usually this order of magnitude). However, the x coordinates set up in
the atsui text-to-glyph code are correct, and the glyphid of the
cairo_glyph_t is unaffected, so this looks to me to be an endianness
issue with doubles creeping in.

This look familiar to anyone?


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