Re: Allocation/gc for pixmaps

It is a known issue, at least in Mac OS. My naive "solution" would be the following. It seems to work in my case when LW is in foreground.

(defun allocation-test ()
  (let ((pane (capi:contain (make-instance 'capi:output-pane))))
    (loop for n from 1 to 1000 do
            (capi:apply-in-pane-process pane (lambda ()
                                               (gp:with-pixmap-graphics-port (image-port pane 854 480 :background :white :clear t)

                                                 ;; Clear the pixmap and draw something
                                                 (gp:draw-rectangle image-port 0 0 854 480 :foreground :white :filled t)
                                                 (gp:draw-string image-port (format nil "Frame ~a" n) 50 50)

                                                 (let ((image (gp:make-image-from-port image-port)))

                                                   ;; ... export the image using e.g. gp:externalize-and-write-image ...

                                                   (gp:free-image image-port image)))))
          when t ;; or some time has passed
            (sleep 0.5 ;; or some other interval
                   ))))

Michal

> 12. 9. 2025 v 17:29, Erik Ronström (as erik dot ronstrom at doremir dot com) <[email protected]>:
> 
> Hi,
> 
> I’m trying to generate a large number of images which are going to be used to create a video. My problem is that the memory footprint of the lisp image grows for each iteration, despite gp:free-image being called.
> 
> I tried to throw in a GC call in the loop, but it seems to have no effect.
> 
> Also, placing gp:with-pixmap-graphics-port inside the loop does not help.
> 
> What am I missing?
> 
> Erik
> 
> 
> (defun allocation-test ()
>  (let ((pane (capi:contain (make-instance 'capi:output-pane))))
>    (capi:apply-in-pane-process pane (lambda ()
>                                       (gp:with-pixmap-graphics-port (image-port pane 854 480 :background :white :clear t)
>                                         (loop for n from 1 to 1000 do
> 
>                                                 ;; Clear the pixmap and draw something
>                                                 (gp:draw-rectangle image-port 0 0 854 480 :foreground :white :filled t)
>                                                 (gp:draw-string image-port (format nil "Frame ~a" n) 50 50)
> 
>                                                 ;; Running GC here has no effect
>                                                 (when (zerop (mod n 20))
>                                                   (gc-generation t))
> 
>                                                 (let ((image (gp:make-image-from-port image-port)))
> 
>                                                   ;; ... export the image using e.g. gp:externalize-and-write-image ...
> 
>                                                   (gp:free-image image-port image))))))))
> 
> 
> 
> 
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