[mcclim-devel] Freetype and CFFI

[Brian Mastenbrook]

Robert Goldman wrote:
> OK.  I stand corrected.  Nevertheless, I argue that a freetype approach 
> based on CFFI, which is portable over non-CMU-derived lisps as well as 
> CMU-derived lisps is preferable, prima facie.
> Now, there may be some additional considerations that would make the 
> CMU-derived-specific approach better, but I don't know of any.  If you 
> do, please let me know.
> 
> Note I'm not trying to brag about my code and denigrate others.  All I 
> did was tweak the CMU-derived-specific approach to backend to CFFI 
> instead, a pretty minor change (and one that I did with virtually no 
> understanding of the code.

To add some historical perspective to the issue:

The mcclim-freetype code was created by Gilbert Baumann. I did the 
initial conversion to SBCL. This involved more than just changing 
package names; in order to make it usable, the code had to be changed 
such that SBCL no longer warned about runtime calls to %SAP-ALIEN. Not 
only did it worn at compile time about this; it actually generated 
warnings at runtime initially too. Along the way, I added a few caches 
to speed up glyph rendering, which finally resulted in something I could 
bear to use daily in climacs and the listener.

Making the compiler happy wrt %SAP-ALIEN was not trivial, and if there's 
anything I would be worried about in the CFFI version, it's that 
somewhere one of those optimizations is not implemented. If it's usably 
fast, I guess everything is OK. Not having used CFFI, I don't know if 
SBCL will still warn about these as profusely as it does when using good 
ol' SB-ALIEN.

-- 
Brian Mastenbrook
brian at mastenbrook.net
http://brian.mastenbrook.net/