Add timer

src/play_clj/core_utils.clj

@@ -0,0 +1,65 @@
+(in-ns 'play-clj.core)
+
+(defmacro scaling
+  "Returns a static field from [Scaling](http://libgdx.badlogicgames.com/nightlies/docs/api/com/badlogic/gdx/utils/Scaling.html)
+
+    (scaling :fill)
+    (scaling :fill-x)
+    (scaling :fill-y)
+    (scaling :fit)
+    (scaling :none)
+    (scaling :stretch)
+    (scaling :stretch-x)
+    (scaling :stretch-y)"
+  [k]
+  `~(u/gdx-field :utils :Scaling k))
+
+(defn ^:private task*
+  "Internal use only."
+  [{:keys [execute-fn! on-timer]} id]
+  (proxy [Timer$Task] []
+    (run []
+      (execute-fn! on-timer :id id))))
+
+(defn ^:private timer*
+  "Internal use only."
+  []
+  (some-> (Class/forName "com.badlogic.gdx.utils.Timer")
+          (try (catch Exception _))
+          .newInstance))
+
+(defn ^:private create-and-add-timer!
+  "Internal use only."
+  [{:keys [update-fn!] :as screen} id]
+  (when-let [timer (timer*)]
+    (update-fn! assoc-in [[:timers id] timer])
+    timer))
+
+(defn add-timer!
+  "Returns a [Timer](http://libgdx.badlogicgames.com/nightlies/docs/api/com/badlogic/gdx/utils/Timer.html)
+that runs the :on-timer function according to the given arguments
+
+    ; wait 2 seconds and run once
+    (add-timer! screen :spawn-enemy 2)
+    ; wait 2 seconds and run forever at 10 second intervals
+    (add-timer! screen :spawn-enemy 2 10)
+    ; wait 2 seconds, run once, and then run 3 more times at 10 second intervals
+    (add-timer! screen :spawn-enemy 2 10 3)"
+  ([screen id delay]
+    (doto (create-and-add-timer! screen id)
+      (.scheduleTask (task* screen id) delay)))
+  ([screen id delay interval]
+    (doto (create-and-add-timer! screen id)
+      (.scheduleTask (task* screen id) delay interval)))
+  ([screen id delay interval repeat]
+    (doto (create-and-add-timer! screen id)
+      (.scheduleTask (task* screen id) delay interval repeat))))
+
+(defn remove-timer!
+  "Stops and removes the timer associated with `id`, returning it or nil if not
+found"
+  [{:keys [update-fn!] :as screen} id]
+  (when-let [timer (get-in screen [:timers id])]
+    (.stop timer)
+    (update-fn! update-in [[:timers] dissoc id])
+    timer))