Avoid serializing to 'typ1' on Mac.

CoreGraphics does not provide a means to get the original font data for a
CGFont, only the tables. As a result, Skia pieces the font data back
together when requested. The most awkward part of this is choosing the
first four bytes, and the CTFont suggestion seems to often be wrong.

This change doublechecks the selection of 'typ1', prefering to use 'OTTO'
if there are no 'TYP1' or 'CID ' tables. These sorts of fonts are
extremely old and unlikely to be in current use. It appears that CTFont
may report that it has this format if it is an 'OTTO' font with very few
glyphs. If Skia serializes such a font with 'typ1' as the first four
bytes, CoreGraphics will not create a CGFont from the resulting font data.

BUG=chromium:809763,skia:7630

Change-Id: I9979b9f0ebdd27c4ad0903e8ee6237241e755541
Reviewed-on: https://skia-review.googlesource.com/113306
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
1 file changed