Tony Kemp <[EMAIL PROTECTED]> writes:

> 
> Hi,
> 
> I've written a simple macro that places a vecto image at the centre of 
> the SDL *default-display*, calculating the co-ordinates based upon the 
> size of the *default-display* and the size of the vecto image. I am 
> trying to get the size of the *default-display* using sdl-base:surf-w 
> and sdl:base:surf-h rather than hard-coding the values, but when I do 
> so, I get the following error:

Hi Tony,

*default-display*, *default-surface* etc. are CLOS objects. The functions in 
SDL-BASE expect foreign pointers. If you want to use sdl-base::surf-w and sdl-
base:surf-h then you must pass the functions in SDL-BASE the pointer to the SDL 
surface stored in *default-display* using SDL:FP. For example:

  (sdl-base::surf-w (sdl:fp *default-display*))
  (sdl-base::surf-h (sdl:fp *default-display*))

However I would suggest using the accessors in the SDL package to do the same 
thing. For example:

  (sdl:width *default-display*)
  (sdl:height *default-display*)

- Luke


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