Quick fix for #83 (#84)

* Quick fix for #83

Co-authored-by: Harsh Bhikadia <[email protected]>

Author: Felix Wortmann

CHANGELOG.md

@@ -1,3 +1,7 @@
+## [0.5.3] - Coming soon
+
+* Fix bug where `_animationController.dispose()` is not called correctly in `BackdropScaffold`[[#83](https://github.com/fluttercommunity/backdrop/pull/83)]
+
 ## [0.5.2] - 27 February 2021
 
 * `example`: referring "live demo" so that it shows up in pub.dev

lib/scaffold.dart

@@ -399,9 +399,10 @@ class BackdropScaffoldState extends State<BackdropScaffold>
           duration: Duration(milliseconds: 200),
           value: widget.revealBackLayerAtStart ? 0 : 1,
         );
-    if (widget.animationController == null && widget.controller == null) {
-      _shouldDisposeAnimationController = true;
-    }
+
+    // should only dispose of `_animationController`, if it was initialised inside this widget.
+    _shouldDisposeAnimationController =
+        (widget.animationController ?? widget.controller) == null;
 
     _backLayerScrimColorTween = _buildBackLayerScrimColorTween();
 
@@ -424,8 +425,8 @@ class BackdropScaffoldState extends State<BackdropScaffold>
 
   @override
   void dispose() {
-    super.dispose();
     if (_shouldDisposeAnimationController) _animationController.dispose();
+    super.dispose();
   }
 
   /// Deprecated. Use [isBackLayerConcealed] instead.