Question

我正在使用此包装。该软件包是提供给flutter滚动组件下拉刷新和拉升负载的小部件。支持android和ios 打包网址为https://pub.dartlang.org/packages/pull_to_refresh 但是这个软件包有一个错误！

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:pull_to_refresh/pull_to_refresh.dart';

class Example1 extends StatefulWidget {
  @override
  _Example1State createState() => new _Example1State();
}

class _Example1State extends State<Example1> {
//  RefreshMode  refreshing = RefreshMode.idle;
//  LoadMode loading = LoadMode.idle;
  RefreshController _refreshController;
  List<Widget> data = [];
  void _getDatas() {
    for (int i = 0; i < 14; i++) {
      data.add(new Card(
        margin:
            new EdgeInsets.only(left: 10.0, right: 10.0, top: 5.0, bottom: 5.0),
        child: new Center(
          child: new Text('Data $i'),
        ),
      ));
    }
  }

  void enterRefresh() {
    _refreshController.requestRefresh(true);
  }

  void _onOffsetCallback(bool isUp, double offset) {
    // if you want change some widgets state ,you should rewrite the callback
  }

  @override
  void initState() {
    // TODO: implement initState
    _getDatas();
    _refreshController = new RefreshController();
    super.initState();
  }

  Widget _headerCreate(BuildContext context, int mode) {
    return new ClassicIndicator(
      mode: mode,
      refreshingText: "",
      idleIcon: new Container(),
      idleText: "Load more...",
    );
  }

//  Widget _footerCreate(BuildContext context,int mode){
//    return new ClassicIndicator(mode: mode);
//  }

  @override
  Widget build(BuildContext context) {
    return new Container(
        child: new SmartRefresher(
            enablePullDown: true,
            enablePullUp: true,
            controller: _refreshController,
            onRefresh: (up) {
              if (up)
                new Future.delayed(const Duration(milliseconds: 2009))
                    .then((val) {
                  data.add(new Card(
                    margin: new EdgeInsets.only(
                        left: 10.0, right: 10.0, top: 5.0, bottom: 5.0),
                    child: new Center(
                      child: new Text('Data '),
                    ),
                  ));

                  _refreshController.scrollTo(_refreshController.scrollController.offset+100.0);
                  _refreshController.sendBack(true, RefreshStatus.idle);
                  setState(() {});
//                refresher.sendStatus(RefreshStatus.completed);
                });
              else {
                new Future.delayed(const Duration(milliseconds: 2009))
                    .then((val) {
                  data.add(new Card(
                    margin: new EdgeInsets.only(
                        left: 10.0, right: 10.0, top: 5.0, bottom: 5.0),
                    child: new Center(
                      child: new Text('Data '),
                    ),
                  ));
                  setState(() {});
                  _refreshController.sendBack(false, RefreshStatus.idle);
                });
              }
            },
            onOffsetChange: _onOffsetCallback,
            child: new ListView.builder(
              reverse: true,
              itemExtent: 100.0,
              itemCount: data.length,
              itemBuilder: (context, index) => new Item(),
            )));
  }
}

class Item extends StatefulWidget {
  @override
  _ItemState createState() => new _ItemState();
}

class _ItemState extends State<Item> {
  @override
  Widget build(BuildContext context) {
    return new Card(
      margin:
          new EdgeInsets.only(left: 10.0, right: 10.0, top: 5.0, bottom: 5.0),
      child: new Center(
        child: new Text('Data'),
      ),
    );
  }

  @override
  void dispose() {
    // TODO: implement dispose
    print("销毁");
    super.dispose();
  }
}

当我点击状态栏时，无法滚动到顶部！我尝试调试此程序包，发现在smart_refresher.dart文件的第344行中，只需注释控制器属性并滚动回顶部，就像这样

但是下拉刷新操作会出现错误。

flutter: ══╡ EXCEPTION CAUGHT BY ANIMATION LIBRARY ╞═════════════════════════════════════════════════════════
flutter: The following assertion was thrown while notifying listeners for AnimationController:
flutter: ScrollController not attached to any scroll views.
flutter: 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 110 pos 12:
flutter: '_positions.isNotEmpty'
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter:   https://github.com/flutter/flutter/issues/new?template=BUG.md
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #2      ScrollController.position (package:flutter/src/widgets/scroll_controller.dart:110:12)
flutter: #3      ScrollController.offset (package:flutter/src/widgets/scroll_controller.dart:118:24)
flutter: #4      _SmartRefresherState._buildWrapperByConfig.<anonymous closure> (package:pull_to_refresh/src/smart_refresher.dart:291:42)
flutter: #5      RefreshWrapperState._handleOffsetCallBack (package:pull_to_refresh/src/internals/indicator_wrap.dart:163:14)
flutter: #6      _AnimationController&Animation&AnimationEagerListenerMixin&AnimationLocalListenersMixin.notifyListeners (package:flutter/src/animation/listener_helpers.dart:124:19)
flutter: #7      AnimationController.value= (package:flutter/src/animation/animation_controller.dart:351:5)
flutter: #8      RefreshWrapperState._handleModeChange (package:pull_to_refresh/src/internals/indicator_wrap.dart:171:25)
flutter: #9      ChangeNotifier.notifyListeners (package:flutter/src/foundation/change_notifier.dart:208:21)
flutter: #10     ValueNotifier.value= (package:flutter/src/foundation/change_notifier.dart:264:5)
flutter: #11     Wrapper.mode= (package:pull_to_refresh/src/internals/indicator_wrap.dart:31:43)
flutter: #12     RefreshWrapperState.onDragEnd (package:pull_to_refresh/src/internals/indicator_wrap.dart:157:14)
flutter: #13     _SmartRefresherState._handleScrollEnd (package:pull_to_refresh/src/smart_refresher.dart:120:40)
flutter: #14     _SmartRefresherState._dispatchScrollEvent (package:pull_to_refresh/src/smart_refresher.dart:133:16)
flutter: #15     NotificationListener._dispatch (package:flutter/src/widgets/notification_listener.dart:125:27)
flutter: #16     Notification.visitAncestor (package:flutter/src/widgets/notification_listener.dart:45:20)
flutter: #17     _ScrollNotification&LayoutChangedNotification&ViewportNotificationMixin.visitAncestor (package:flutter/src/widgets/scroll_notification.dart:31:18)
flutter: #18     Element.visitAncestorElements (package:flutter/src/widgets/framework.dart:3344:39)
flutter: #19     Notification.dispatch (package:flutter/src/widgets/notification_listener.dart:59:12)
flutter: #20     ScrollActivity.dispatchScrollUpdateNotification (package:flutter/src/widgets/scroll_activity.dart:96:92)
flutter: #21     ScrollPosition.didUpdateScrollPositionBy (package:flutter/src/widgets/scroll_position.dart:654:14)
flutter: #22     ScrollPosition.setPixels (package:flutter/src/widgets/scroll_position.dart:219:9)
flutter: #23     ScrollPositionWithSingleContext.setPixels (package:flutter/src/widgets/scroll_position_with_single_context.dart:84:18)
flutter: #24     BallisticScrollActivity.applyMoveTo (package:flutter/src/widgets/scroll_activity.dart:547:21)
flutter: #25     BallisticScrollActivity._tick (package:flutter/src/widgets/scroll_activity.dart:534:10)
flutter: #26     _AnimationController&Animation&AnimationEagerListenerMixin&AnimationLocalListenersMixin.notifyListeners (package:flutter/src/animation/listener_helpers.dart:124:19)
flutter: #27     AnimationController._tick (package:flutter/src/animation/animation_controller.dart:697:5)
flutter: #28     Ticker._tick (package:flutter/src/scheduler/ticker.dart:228:5)
flutter: #29     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
flutter: #30     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleBeginFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:906:11)
flutter: #31     __InternalLinkedHashMap&_HashVMBase&MapMixin&_LinkedHashMapMixin.forEach (dart:collection/runtime/libcompact_hash.dart:370:8)
flutter: #32     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleBeginFrame (package:flutter/src/scheduler/binding.dart:904:17)
flutter: #33     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleBeginFrame (package:flutter/src/scheduler/binding.dart:834:5)
flutter: #34     _invoke1 (dart:ui/hooks.dart:168:13)
flutter: #35     _beginFrame (dart:ui/hooks.dart:138:3)
flutter: (elided 2 frames from class _AssertionError)
flutter:
flutter: The AnimationController notifying listeners was:
flutter:   AnimationController#96484(⏭ 1.000; paused)
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
flutter: Another exception was thrown: ScrollController not attached to any scroll views.
[VERBOSE-2:shell.cc(184)] Dart Error: Unhandled exception:
'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 110 pos 12: '_positions.isNotEmpty': ScrollController not attached to any scroll views.
#0      _AssertionError._doThrowNew (dart:core/runtime/liberrors_patch.dart:40:39)
#1      _AssertionError._throwNew (dart:core/runtime/liberrors_patch.dart:36:5)
#2      ScrollController.position (package:flutter/src/widgets/scroll_controller.dart:110:12)
#3      ScrollController.offset (package:flutter/src/widgets/scroll_controller.dart:118:24)
#4      _Example1State.build.<anonymous closure>.<anonymous closure> (package:example/ui/Example1.dart:76:83)
#5      _RootZone.runUnary (dart:async/zone.dart:1379:54)
#6      _FutureListener.handleValue (dart:async/future_impl.dart:129:18)
#7      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:642:45)
#8      Future._propagateToListeners (dart:async/future_impl.dart:671:32)
#9      Future._complete (dart:as<…>

iOS状态栏点击失败滚动到顶部

0 个答案: