Introduced MiniplayerWillPopScope as a drop-in replacement for WillPopScope to work with a nested architecture

lib/miniplayer.dart

@@ -3,8 +3,11 @@ library miniplayer;
 import 'dart:async';
 
 import 'package:flutter/material.dart';
+import 'package:miniplayer/src/miniplayer_will_pop_scope.dart';
 import 'package:miniplayer/src/utils.dart';
 
+export 'package:miniplayer/src/miniplayer_will_pop_scope.dart';
+
 ///Type definition for the builder function
 typedef Widget MiniplayerBuilder(double height, double percentage);
 
@@ -142,7 +145,7 @@ class _MiniplayerState extends State<Miniplayer> with TickerProviderStateMixin {
   Widget build(BuildContext context) {
     if (dismissed) return Container();
 
-    return WillPopScope(
+    return MiniplayerWillPopScope(
       onWillPop: () async {
         if (heightNotifier.value > widget.minHeight) {
           _snapToPosition(PanelState.MIN);

lib/src/miniplayer_will_pop_scope.dart

@@ -0,0 +1,67 @@
+import 'package:flutter/material.dart';
+
+class MiniplayerWillPopScope extends StatefulWidget {
+  const MiniplayerWillPopScope({
+    Key key,
+    @required this.child,
+    @required this.onWillPop,
+  })  : assert(child != null),
+        super(key: key);
+
+  final Widget child;
+  final WillPopCallback onWillPop;
+
+  @override
+  _MiniplayerWillPopScopeState createState() => _MiniplayerWillPopScopeState();
+
+  static _MiniplayerWillPopScopeState of(BuildContext context) {
+    return context.findAncestorStateOfType<_MiniplayerWillPopScopeState>();
+  }
+}
+
+class _MiniplayerWillPopScopeState extends State<MiniplayerWillPopScope> {
+  ModalRoute<dynamic> _route;
+
+  _MiniplayerWillPopScopeState _descendant;
+
+  set descendant(state) {
+    _descendant = state;
+    updateRouteCallback();
+  }
+
+  Future<bool> onWillPop() async {
+    bool willPop;
+    if (_descendant != null) {
+      willPop = await _descendant.onWillPop();
+    }
+    if (willPop == null || willPop) {
+      willPop = await widget.onWillPop();
+    }
+    return willPop;
+  }
+
+  void updateRouteCallback() {
+    _route?.removeScopedWillPopCallback(onWillPop);
+    _route = ModalRoute.of(context);
+    _route?.addScopedWillPopCallback(onWillPop);
+  }
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    var parentGuard = MiniplayerWillPopScope.of(context);
+    if (parentGuard != null) {
+      parentGuard.descendant = this;
+    }
+    updateRouteCallback();
+  }
+
+  @override
+  void dispose() {
+    _route?.removeScopedWillPopCallback(onWillPop);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => widget.child;
+}