;;; -*- lexical-binding: t -*-
;;
;; -----------------------------------------------------------------------------
;; this file:
;;   https://dataswamp.org/~incal/emacs-init/draw/draw.el
;; -----------------------------------------------------------------------------

(require 'cl-lib)
(cl-pushnew "."                          load-path :test #'string=)
(cl-pushnew (file-name-concat ".." "ll") load-path :test #'string=)
(require 'luki-lisp)

(let ((dm "draw.so"))
  (load dm nil t)
  (declare-function sdl2_init dm)
  (declare-function draw_init dm)
  (declare-function draw_quit dm)
  (declare-function draw_draw dm))

(defun buffer-substring-no-properties-in-window ()
  (when-let* ((beg (or (win-beg) (point-min)))
              (end (or (win-end) (point-max)))
              (str (buffer-substring-no-properties beg end))
              (fbk "No data")
              (fnl (or (& (su str) str) fbk)))
    (replace-regexp-in-string "\\(.+\\)$" "\\1\n" fnl)))

(defun sdl2-draw-init ()
  (draw_init))

;; (sdl2-draw-init)

(defun sdl2-draw-quit ()
  (draw_quit))

;; (sdl2-draw-quit)

(defun sdl2-draw-draw ()
  (draw_draw))

(defun sdl2-test-fps ()
  (setq current-time-list nil)
  (pop-buff (get-buffer-create "*fps-test*"))
  (sdl2-draw-init)
  (cl-loop
   with fps         = 60
   with (beg . hz)  = (time-convert nil nil)
   with frame-ticks = (/ hz fps)
   with frames      = (** 2 8)
   for f from 1 upto frames
   for next = (+ beg (* f frame-ticks)) do
     (erase-buffer)
     (@i (@f " \n  GNU Emacs %d.%d" emacs-major-version emacs-minor-version)
         (@f  "\n  with SDL2")
         (@f  "\n  frame %d of %d (%.1f%%)  \n" f frames (* 100 (// f frames)))
         (@f  "\n  %.2f fps\n " (// (* hz f) (- (1st (time-convert nil nil)) beg))))
     (sdl2-draw-draw)
     (sleep-for (// (- next (1st (time-convert nil nil))) hz))
   finally
     (let ((end (- (1st (time-convert nil nil)) beg)))
       (shell-command "scrot -o \"fps.png\"" t)
       (sleep-for 8)
       (sdl2-draw-quit)
       ($ "%.3f fps" (// (* hz frames) end)))))

(defun sdl2-init ()
  (sdl2_init "SDL2 & GNU Emacs"))

(<- 'draw)