javafx semicircle using cljfx

core.clj

(ns semicircle.core
  (:require
    [cljfx.api :as fx]
  (:import
    [javafx.application Platform]
    [javafx.scene.paint Color]
    [javafx.scene.canvas Canvas])
  (:gen-class))
  
(def *state
  (atom {}))
  
;; https://stackoverflow.com/questions/11719005/draw-a-semi-ring-javafx  
(defn semicircle [centerx centery radius inner-radius bgcolor stroke-color]
  (let [move-to {:fx/type :move-to
                 :x (+ centerx inner-radius)
                 :y centery}
        inner-arc {:fx/type :arc-to
                   :x (- centerx inner-radius)
                   :y centery
                   :radius-x inner-radius
                   :radius-y inner-radius}
        move-to-2 {:fx/type :move-to
                   :x (- centerx inner-radius)
                   :y centery}
        hline-to-right-leg {:fx/type :h-line-to
                            :x (+ centerx radius)}
        outer-arc {:fx/type :arc-to
                   :x (- centerx radius)
                   :y centery
                   :radius-x radius
                   :radius-y radius}
        hline-to-left-leg {:fx/type :h-line-to
                           :x (- centerx inner-radius)}
        path {:fx/type   :path
              :fill      bgcolor
              :stroke    stroke-color
              :fill-rule :even-odd
              :elements [move-to inner-arc move-to-2 hline-to-right-leg outer-arc hline-to-right-leg]}]
    ; return it
    path))
  
(defn root-view
  "This defines the root view"
  []
  {:fx/type :stage
   :width 200
   :height 200
   :showing true
   :scene {:fx/type :scene
           :root {:fx/type :v-box
                  :children [(semicircle 120 120 100 50 :lightgreen :transparent)]}}})
(def renderer
  (fx/create-renderer
   :middleware (fx/wrap-map-desc (fn [state]
                                   {:fx/type root-view
                                    :state state}))))
(defn -main []
  (Platform/setImplicitExit(true))
  (fx/mount-renderer *state renderer)
  (println "Hello, World!"))