;; using nanovg_helper lib
(bind-func draw_a_circle
(lambda ()
(nvgBeginFrame vg (convert width) (convert height) pixel_ratio)
(nvgBeginPath vg)
(xtm_draw_circle_stroke vg 400 400 100 xtm_green 20)
(xtm_fill vg xtm_blue)
(nvgEndFrame vg)))