[Qt-interest] Text Handling speed on Mac (ATSUI, Core Text, Harfbuzz?)

[James Larcombe]

Joshua Grauman wrote: 

> 1) Can someone confirm that Qt is still using ATSUI for Mac?
> 
> 2) Is there any plans to move to Core Text or even Harfbuzz on Mac?

Qt will use Core Text when built against Cocoa. This is the default for
64-bit builds, but I believe 32-bit builds will still use Carbon/ATSUI
etc by default. We're using the Cocoa build on both 32 and 64-bit and
it's working well.

> 3) Is there any reason I couldn't make a couple minor changes to the
Qt 
> code and use Harfbuzz on Mac (I don't need any system fonts, I supply
all 
> my own which are all TrueType/OpenType).

I've not investigated this, though the idea is interesting. In my
experience so far, the Core Text engine is rather more capable than the
Harfbuzz implementation on Windows. For example the latter doesn't
correctly kern OpenType fonts using the GPOS table (see QTBUG-11389).

James