lispbuilder-sdl-ttf-cffi::ttf-size-text doesn't have nice lisp wrapper #38

What steps will reproduce the problem?
1. Desire to figure out the extent of piece of text rendered with a font.
2. Search the docs religiously which don't mention it and then the code itself. 
3. Discover that CFFI implements a call to TTF_SizeText(), but noone uses it.

What is the expected output? What do you see instead?

I see no output, because the lowlevel CFFI wrapper isn't exported and doesn't 
have
a nice lisp wrapper.

What version of the product are you using? On what operating system?

I'm using lispbuilder-20120520-svn from quicklisp as of a little bit ago with
SBCL 1.0.57 on an Ubuntu 10.04 LTS x86 machine.

Please provide any additional information below.

Here is a starting point for a wrapper function:

(defun text-size (font str)
  (let ((fp-width (cffi:foreign-alloc :int))
        (fp-height (cffi:foreign-alloc :int)))

    (lispbuilder-sdl-ttf-cffi::ttf-size-text
     (sdl:fp font) str fp-width fp-height)

    (values (cffi:mem-ref fp-height :int) (cffi:mem-ref fp-width :int))))


Thank you and have a nice day!