_TabBarViewState should dispose created instances of PageController. (#134091)

Author: polina-c

packages/flutter/lib/src/material/tabs.dart

@@ -1783,7 +1783,7 @@ class TabBarView extends StatefulWidget {
 
 class _TabBarViewState extends State<TabBarView> {
   TabController? _controller;
-  late PageController _pageController;
+  PageController? _pageController;
   late List<Widget> _childrenWithKey;
   int? _currentIndex;
   int _warpUnderwayCount = 0;
@@ -1825,7 +1825,7 @@ class _TabBarViewState extends State<TabBarView> {
 
   void _jumpToPage(int page) {
     _warpUnderwayCount += 1;
-    _pageController.jumpToPage(page);
+    _pageController!.jumpToPage(page);
     _warpUnderwayCount -= 1;
   }
 
@@ -1835,7 +1835,7 @@ class _TabBarViewState extends State<TabBarView> {
     required Curve curve,
   }) async {
     _warpUnderwayCount += 1;
-    await _pageController.animateToPage(page, duration: duration, curve: curve);
+    await _pageController!.animateToPage(page, duration: duration, curve: curve);
     _warpUnderwayCount -= 1;
   }
 
@@ -1850,6 +1850,8 @@ class _TabBarViewState extends State<TabBarView> {
     super.didChangeDependencies();
     _updateTabController();
     _currentIndex = _controller!.index;
+    // TODO(chunhtai): https://github.com/flutter/flutter/issues/134253
+    _pageController?.dispose();
     _pageController = PageController(
       initialPage: _currentIndex!,
       viewportFraction: widget.viewportFraction,
@@ -1877,6 +1879,7 @@ class _TabBarViewState extends State<TabBarView> {
       _controller!.animation!.removeListener(_handleTabControllerAnimationTick);
     }
     _controller = null;
+    _pageController?.dispose();
     // We don't own the _controller Animation, so it's not disposed here.
     super.dispose();
   }
@@ -1897,7 +1900,7 @@ class _TabBarViewState extends State<TabBarView> {
   }
 
   void _warpToCurrentIndex() {
-    if (!mounted || _pageController.page == _currentIndex!.toDouble()) {
+    if (!mounted || _pageController!.page == _currentIndex!.toDouble()) {
       return;
     }
 
@@ -1957,7 +1960,7 @@ class _TabBarViewState extends State<TabBarView> {
   }
 
   void _syncControllerOffset() {
-    _controller!.offset = clampDouble(_pageController.page! - _controller!.index, -1.0, 1.0);
+    _controller!.offset = clampDouble(_pageController!.page! - _controller!.index, -1.0, 1.0);
   }
 
   // Called when the PageView scrolls
@@ -1975,15 +1978,16 @@ class _TabBarViewState extends State<TabBarView> {
     }
 
     _scrollUnderwayCount += 1;
+    final double page = _pageController!.page!;
     if (notification is ScrollUpdateNotification && !_controller!.indexIsChanging) {
-      final bool pageChanged = (_pageController.page! - _controller!.index).abs() > 1.0;
+      final bool pageChanged = (page - _controller!.index).abs() > 1.0;
       if (pageChanged) {
-        _controller!.index = _pageController.page!.round();
+        _controller!.index = page.round();
         _currentIndex =_controller!.index;
       }
       _syncControllerOffset();
     } else if (notification is ScrollEndNotification) {
-      _controller!.index = _pageController.page!.round();
+      _controller!.index = page.round();
       _currentIndex = _controller!.index;
       if (!_controller!.indexIsChanging) {
         _syncControllerOffset();

packages/flutter/test/material/page_selector_test.dart

@@ -84,14 +84,7 @@ void main() {
     await tester.pump();
     expect(tabController.index, 2);
     expect(indicatorColors(tester), const <Color>[kUnselectedColor, kUnselectedColor, kSelectedColor]);
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 1,
-    },
-  ));
+  });
 
   testWidgetsWithLeakTracking('PageSelector responds correctly to TabController.animateTo()', (WidgetTester tester) async {
     final TabController tabController = TabController(
@@ -134,14 +127,7 @@ void main() {
     await tester.pumpAndSettle();
     expect(tabController.index, 2);
     expect(indicatorColors(tester), const <Color>[kUnselectedColor, kUnselectedColor, kSelectedColor]);
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 1,
-    },
-  ));
+  });
 
   testWidgetsWithLeakTracking('PageSelector responds correctly to TabBarView drags', (WidgetTester tester) async {
     final TabController tabController = TabController(
@@ -199,14 +185,7 @@ void main() {
     await tester.fling(find.byType(TabBarView), const Offset(100.0, 0.0), 1000.0);
     await tester.pumpAndSettle();
     expect(indicatorColors(tester), const <Color>[kUnselectedColor, kSelectedColor, kUnselectedColor]);
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 1,
-    },
-  ));
+  });
 
   testWidgetsWithLeakTracking('PageSelector indicatorColors', (WidgetTester tester) async {
     const Color kRed = Color(0xFFFF0000);
@@ -225,14 +204,7 @@ void main() {
     tabController.index = 0;
     await tester.pumpAndSettle();
     expect(indicatorColors(tester), const <Color>[kBlue, kRed, kRed]);
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 1,
-    },
-  ));
+  });
 
   testWidgets('PageSelector indicatorSize', (WidgetTester tester) async {
     final TabController tabController = TabController(
@@ -299,12 +271,5 @@ void main() {
     for (final TabPageSelectorIndicator indicator in indicators) {
       expect(indicator.borderStyle, BorderStyle.solid);
     }
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 1,
-    },
-  ));
+  });
 }

packages/flutter/test/material/scrollbar_test.dart

@@ -1834,14 +1834,7 @@ void main() {
     );
 
     scrollController.dispose();
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 2,
-    },
-  ));
+  });
 
   testWidgetsWithLeakTracking('Scrollbar scrollOrientation works correctly', (WidgetTester tester) async {
     final ScrollController scrollController = ScrollController();

packages/flutter/test/material/tabbed_scrollview_warp_test.dart

@@ -81,12 +81,5 @@ void main() {
     // should not crash.
     await tester.tap(find.text('Tab 2'));
     await tester.pumpAndSettle();
-  },
-  // TODO(someone): remove after fixing
-  // https://github.com/flutter/flutter/issues/133755
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?>{
-      'PageController': 1,
-    },
-  ));
+  });
 }