Good looking version of image preview

Author: kmagiera

Example/Reanimated/AnimatedImplementation.js

@@ -26,6 +26,10 @@ const add = function(a, b) {
   return new AnimatedOp([adapt(a), adapt(b)], ([a, b]) => a + b);
 };
 
+const sub = function(a, b) {
+  return new AnimatedOp([adapt(a), adapt(b)], ([a, b]) => a - b);
+};
+
 const pow = function(a, b) {
   return new AnimatedOp([adapt(a), adapt(b)], ([a, b]) => Math.pow(a, b));
 };
@@ -573,7 +577,7 @@ module.exports = {
    * See http://facebook.github.io/react-native/docs/animated.html#add
    */
   add,
-
+  sub,
   cond,
   block,
   set,

Example/Reanimated/utils.js

@@ -6,7 +6,7 @@ export function adapt(v) {
 }
 
 export function val(v) {
-  return v.__getValue ? v.__getValue() : v;
+  return v && v.__getValue ? v.__getValue() : v || 0;
 }
 
 export function proxyAnimatedObject(target) {