ensure new value applied.

lib/ring_indicator.dart

@@ -106,11 +106,17 @@ class _RingIndicatorState extends State<RingIndicator> {
     ticker = Ticker((_) {
       var diff = DateTime.now().difference(startTime).inMilliseconds;
       if (diff > 300) {
+        _applyChangeToSelfAndParent(newValue);
         return ticker?.stop();
       }
-      if (mounted) {
+      _applyChangeToSelfAndParent(oldValue + (newValue - oldValue) * (diff / 300));
+    })
+      ..start();
+  }
+
+  _applyChangeToSelfAndParent(double value) {
     setState(() {
-          _value = oldValue + (newValue - oldValue) * (diff / 300);
+      _value = value;
       values[0] = LevelValue(_value);
     });
     if (parent != null) {
@@ -119,9 +125,6 @@ class _RingIndicatorState extends State<RingIndicator> {
       }
     }
   }
-    })
-      ..start();
-  }
 
   @override
   void initState() {