Fix SliverReorderableList item dispose (#105097)

Author: TahaTesser

packages/flutter/lib/src/widgets/reorderable_list.dart

@@ -603,8 +603,7 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
 
   @override
   void dispose() {
-    _dragInfo?.dispose();
-    _autoScroller?.stopAutoScroll();
+    _dragReset();
     super.dispose();
   }
 
@@ -658,7 +657,9 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
   ///
   /// If no drag is active, this will do nothing.
   void cancelReorder() {
-    _dragReset();
+    setState(() {
+      _dragReset();
+    });
   }
 
   void _registerItem(_ReorderableItemState item) {
@@ -724,7 +725,9 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
   }
 
   void _dragCancel(_DragInfo item) {
-    _dragReset();
+    setState(() {
+      _dragReset();
+    });
   }
 
   void _dragEnd(_DragInfo item) {
@@ -753,29 +756,29 @@ class SliverReorderableListState extends State<SliverReorderableList> with Ticke
     if (fromIndex != toIndex) {
       widget.onReorder.call(fromIndex, toIndex);
     }
-    _dragReset();
+    setState(() {
+      _dragReset();
+    });
   }
 
   void _dragReset() {
-    setState(() {
-      if (_dragInfo != null) {
-        if (_dragIndex != null && _items.containsKey(_dragIndex)) {
-          final _ReorderableItemState dragItem = _items[_dragIndex!]!;
-          dragItem._dragging = false;
-          dragItem.rebuild();
-          _dragIndex = null;
-        }
-        _dragInfo?.dispose();
-        _dragInfo = null;
-        _autoScroller?.stopAutoScroll();
-        _resetItemGap();
-        _recognizer?.dispose();
-        _recognizer = null;
-        _overlayEntry?.remove();
-        _overlayEntry = null;
-        _finalDropPosition = null;
+    if (_dragInfo != null) {
+      if (_dragIndex != null && _items.containsKey(_dragIndex)) {
+        final _ReorderableItemState dragItem = _items[_dragIndex!]!;
+        dragItem._dragging = false;
+        dragItem.rebuild();
+        _dragIndex = null;
       }
-    });
+      _dragInfo?.dispose();
+      _dragInfo = null;
+      _autoScroller?.stopAutoScroll();
+      _resetItemGap();
+      _recognizer?.dispose();
+      _recognizer = null;
+      _overlayEntry?.remove();
+      _overlayEntry = null;
+      _finalDropPosition = null;
+    }
   }
 
   void _resetItemGap() {

packages/flutter/test/widgets/reorderable_list_test.dart

@@ -1005,6 +1005,73 @@ void main() {
       expect(items, orderedEquals(<int>[0, 1, 2, 3, 4]));
     });
   });
+
+  testWidgets('SliverReorderableList properly disposes items', (WidgetTester tester) async {
+    // Regression test for https://github.com/flutter/flutter/issues/105010
+    const int itemCount = 5;
+    final List<int> items = List<int>.generate(itemCount, (int index) => index);
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          appBar: AppBar(),
+          drawer: Drawer(
+            child: Builder(
+              builder: (BuildContext context) {
+                return Column(
+                  children: <Widget>[
+                    Expanded(
+                      child: CustomScrollView(
+                        slivers: <Widget>[
+                          SliverReorderableList(
+                            itemCount: itemCount,
+                            itemBuilder: (BuildContext context, int index) {
+                              return Material(
+                                key: ValueKey<String>('item-$index'),
+                                child: ReorderableDragStartListener(
+                                  index: index,
+                                  child: ListTile(
+                                    title: Text('item ${items[index]}'),
+                                  ),
+                                ),
+                              );
+                            },
+                            onReorder: (int oldIndex, int newIndex) {},
+                          ),
+                        ],
+                      ),
+                    ),
+                    TextButton(
+                      onPressed: () {
+                        Scaffold.of(context).closeDrawer();
+                      },
+                      child: const Text('Close drawer'),
+                    ),
+                  ],
+                );
+              }
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.tap(find.byIcon(Icons.menu));
+    await tester.pumpAndSettle();
+
+    final Finder item0 = find.text('item 0');
+    expect(item0, findsOneWidget);
+
+    // Start gesture on first item without drag up event.
+    final TestGesture drag = await tester.startGesture(tester.getCenter(item0));
+    await drag.moveBy(const Offset(0, 200));
+    await tester.pump();
+
+    await tester.tap(find.text('Close drawer'));
+    await tester.pumpAndSettle();
+
+    expect(item0, findsNothing);
+  });
 }
 
 class TestList extends StatefulWidget {