;; using nanovg_helper lib
(bind-func draw_a_line
(lambda ()
(nvgBeginFrame vg (convert width) (convert height) pixel_ratio)
(nvgBeginPath vg)
(xtm_draw_line vg 0 0 400 400 (xtm_rgba 255 0 0 255) 5)
;; (xtm_draw_line vg 2.5 2.5 402.5 402.5 (xtm_rgba 1. 0. 0. 1.) 5.5) ;; float type arguments are OK
(nvgEndFrame vg)))