(use (prefix glfw3 glfw:)
     (prefix opengl-glew gl:)
     (prefix nuklear nk:))

(require-library nuklear-glfw-opengl2)
(import (prefix nuklear-glfw-opengl2 backend:))

(define width 250)
(define height 150)

(glfw:init)
(glfw:make-window width height "Hello World")
(glfw:make-context-current (glfw:window))
(set!-values (width height) (glfw:get-window-size (glfw:window)))

(define context (backend:init! (glfw:window) #t))
(backend:init-font!)

(define quit? #f)
(define show-greeting? #f)

(define layout (nk:make-panel))
(define popup-layout (nk:make-panel))
(define garbage #f)

(let loop ()
  (when (and (not (glfw:window-should-close (glfw:window))) (not quit?))
    (glfw:poll-events)
    (backend:new-frame)

    (when (nk:window-begin context layout "Hello World!"
                           (nk:make-rect 10 10 192 100)
                           '(border no-scrollbar movable))
      (when (= 0 (random 10)) (print* "GC") (gc #t)
            (when (= 0 (random 2)) (print* "2")
                  (set! garbage (make-blob (random 100000)))
                  (gc #t)))
      (nk:layout-row-dynamic context 30 2)
      (when (nk:button-label context "Click Me!")
        (printf "Yay\n")
        (set! show-greeting? #t))
      (when (nk:button-label context "Quit")
        (set! quit? #t))

      (when show-greeting?
        (if (nk:popup-begin context popup-layout #f "Greeting" '(dynamic)
                            (nk:make-rect 15 50 200 150))
            (begin
              (nk:layout-row-dynamic context 25 1)
              (nk:label context "Hello World!" 'centered)
              (nk:layout-row-dynamic context 25 1)
              (when (nk:button-label context "OK")
                (set! show-greeting? #f)
                (nk:popup-close context))
              (nk:popup-end context))
            (set! show-greeting? #f))))
    (nk:window-end context)

    (let-values (((width height) (glfw:get-window-size (glfw:window))))
      (gl:viewport 0 0 width height))
    (gl:clear gl:+color-buffer-bit+)
    (gl:clear-color (/ 28 255) (/ 48 255) (/ 62 255) 0)
    (backend:render!)
    (glfw:swap-buffers (glfw:window))
    (loop)))

(backend:shutdown!)
(glfw:terminate)

;; $ hg diff hello-world.scm 
;; diff -r 980803bb2342 4/nuklear/examples/hello-world/hello-world.scm
;; --- a/4/nuklear/examples/hello-world/hello-world.scm    Sun Jan 20 09:19:01 2019 +0200
;; +++ b/4/nuklear/examples/hello-world/hello-world.scm    Sat Feb 09 16:20:48 2019 +0200
;; @@ -21,6 +21,7 @@
;;  
;;  (define layout (nk:make-panel))
;;  (define popup-layout (nk:make-panel))
;; +(define garbage #f)
;;  
;;  (let loop ()
;;    (when (and (not (glfw:window-should-close (glfw:window))) (not quit?))
;; @@ -30,6 +31,10 @@
;;      (when (nk:window-begin context layout "Hello World!"
;;                             (nk:make-rect 10 10 192 100)
;;                             '(border no-scrollbar movable))
;; +      (when (= 0 (random 10)) (print* "GC") (gc #t)
;; +            (when (= 0 (random 2)) (print* "2")
;; +                  (set! garbage (make-blob (random 100000)))
;; +                  (gc #t)))
;;        (nk:layout-row-dynamic context 30 2)
;;        (when (nk:button-label context "Click Me!")
;;          (printf "Yay\n")