Re: [Chicken-users] Updated sdl.egg

[Alex Shinn]

At Sun, 24 Oct 2004 12:00:43 +0100, Tony Garnock-Jones wrote:
> 
> v0.1.1 alpha - new functions for SDL_image and SDL_rotozoom.

Hi!  Thanks a lot for the SDL bindings, I've been meaning to do this
myself but haven't had time.  I can help you test though ;)

A few comments:

For the naming convention you translate SDL_StudlyCaps into
sdl-studlycaps, but sdl-studly-caps is more Schemey, and is also the
naming style used in both guile-sdl and gauche-sdl.

It would be a nice shorthand to be able to say

  (make-sdl-color r g b)

instead of

  (fill-sdl-color! (make-sdl-color) r g b)

You have a comment on line 215 of sdl.scm:

;; %%% clip_rect?

Setting a clip rect means restricting all changes to a specific
rectangle within a surface.  It's very useful for animations and
sprite operations, and should definitely be included.  A quick
implementation would be something like:

(define sdl-set-clip-rect
  (foreign-lambda unsigned-short "SDL_SetClipRect" SDL_Surface SDL_Rect))

(define sdl-get-clip-rect
  (foreign-lambda* SDL_Rect ((SDL_Surface s))
     "SDL_Rect *r;"
     "r = (SDL_Rect *) malloc(sizeof(SDL_Rect));"
     "SDL_GetClipRect(s, r);"
     "return r;"))

but this fails to handle NULL rects (used for disabling the clip rect)
correctly.

A handy idiom with clip rects is the following utility:

(define (sdl-with-clip-rect r thunk)
  (let* ((s (sdl-getvideosurface))
         (orig-clip-rect (sdl-get-clip-rect s)))
    (dynamic-wind
        (lambda () (sdl-set-clip-rect s r))
        thunk
        (lambda () (sdl-set-clip-rect s orig-clip-rect)))))

which could optionally take 3 arguments with the 1st argument being
the surface.

Thanks again!

-- 
Alex