[Interest] harfbuzz support?

[René J.V. Bertin]

Hi,

Qt can be built with or without support for text rendering using
harfbuzz. Qt4 and Qt5 seem to differ slightly in this aspect, but from
what I understand both can be made to use harfbuzz at runtime even
when not compiled to use it (by default).
I'd like to test this, as it would probably let text rendering benefit
from the Infinality patches I have applied to my FreeType library.

I checked my build of the Qt 4.8.7 snapshot released the other day:
it's been built without giving a harfbuzz option, which should be
equivalent to

 *  -no-harfbuzz ....... Disable HarfBuzz on Mac. It can still be
enabled by setting
                         QT_ENABLE_HARFBUZZ environment variable.

However, I don't see any difference when I set QT_ENABLE_HARFBUZZ=1 .
That doesn't seem too surprising given that none of the frameworks in
my build appear to link to harfbuzz, nor does the library seem to be
loaded dynamically.

Is it possible that that statement above is incorrect, and that one
can disable harfbuzz in order to use CoreText instead after building
with -harfbuzz?

The Qt5 build options are more complex, and refer to "old" behaviour
obtained with QT_HARFBUZZ=1; does that mean CoreText rendering on OS
X?

Thanks,
René