davidhellsing · February 20, 2019 13:38 · Feb 20, 2019 · Feb 20, 2019
diff --git a/gistfile1.txt → gistfile1.ts b/gistfile1.txt → gistfile1.ts
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,48 @@
+import { Easing } from 'react-native'
+
+/*
+ * Function that animates a value from 0 - 1
+ * Uses React Native’s Easing functions
+ * Returns an object that has a stop() function
+ */
+
+interface Args {
+  duration: number,
+  easing?: (value: number) => number,
+  onFrame?: (value: number) => void,
+  onComplete?: () => void,
+}
+
+export type AnimationReturnType = {
+  stop: () => void,
+}
+
+export default ({ 
+  duration = 800, 
+  easing = Easing.inOut(Easing.quad), 
+  onFrame, 
+  onComplete
+}: Args) => {
+  let stopped = false
+  const returnObject: AnimationReturnType = {
+    stop: () => {
+      stopped = true
+    },
+  }
+  const then = Date.now()
+  function loop() {
+    if (!stopped) {
+      const time = Date.now() - then
+      if (time > duration) {
+        if (onComplete) {
+          onComplete()
+        }
+      } else if (onFrame) {
+        onFrame(easing(time / duration))
+        requestAnimationFrame(loop)
+      }
+    }
+  }
+  loop()
+  return returnObject
+}