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我目前正在开发一个需要列表视图作为 ScrollView 子项的项目。我在列表视图中添加了一个滚动控制器,在滚动控制器中添加了一个滚动监听器。但是监听器方法永远不会被调用。如果我在父滚动视图中添加控制器,就会调用它。我需要listview的监听器,因为我必须在滚动时通过api调用分页数据。这是我的代码:

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter_calendar_carousel/classes/event.dart';
import 'package:flutter_calendar_carousel/flutter_calendar_carousel.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:http/http.dart' as http;
import 'package:hub_food_park/network/network_helper.dart';
import 'package:hub_food_park/pojos/event/event_item.dart';
import 'package:hub_food_park/pojos/event/event_result.dart';
import 'package:hub_food_park/utils/constants.dart';
import 'package:intl/intl.dart';

class FirstScreen extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _FirstScreeState();
  }
}

class _FirstScreeState extends State<FirstScreen> {
  DateTime _currentDate = DateTime.now();
  bool isEmpty = false;

  String _currentMonth = '';
  String monthHeader = '';
  NetworkHelper mHelper;

  int listSize = 0;

  List<Events> eventList = List<Events>();

  Future<List<Events>> future;

  CalendarCarousel _calendarCarousel;

  String selectedDate = '';

  String _currentYear = '';

  bool isMonthly = false;

  Color color;

  bool isLoading = false;

  int pageNo = 0;

  ScrollController _listScrollController;
  String message;

  List<String> monthNames = [
    'January',
    'February',
    'March',
    'April',
    'May',
    'June',
    'July',
    'August',
    'September',
    'October',
    'November',
    'December'
  ];

  final GlobalKey widgetKey = GlobalKey();

  void _changed(bool visibility) {
    setState(() {
      isEmpty = visibility;
    });
  }

  String _getFormattedDate(DateTime dateTime) {
    var formatter = new DateFormat('yyyy-MM-dd');
    String formattedDate = formatter.format(dateTime);
    return formattedDate;
  }

  @override
  void initState() {
    _listScrollController = ScrollController();
    _listScrollController.addListener(_scrollListener);
    super.initState();
    var d = DateTime.now();
    DateTime dateTime = DateTime(d.year, d.month, d.day);
    selectedDate = _getFormattedDate(dateTime);
    _currentMonth = selectedDate.substring(5, 7);
    _currentYear = selectedDate.substring(0, 4);
    print(_currentMonth + ' ' + _currentYear);
    mHelper = new NetworkHelper('events');
    //  getList(selectedDate, pageNo);
    future = _getTodaysEvent(selectedDate);
  }

  void getList(String selectedDate, int pageNo) {
    mHelper.setUrl('events');
    mHelper.getEventList(selectedDate, pageNo).then((v) {
      setState(() {
        if (v.events != null) {
          print(v.events.length);
          listSize = v.events.length;
          eventList.addAll(v.events);
          _changed(false);
        } else {
          print(v.message);
          if (pageNo == 0) {
            _changed(true);
          }
          pageNo = 0;
        }
      });
    });
  }

  void getMonthlyEventList(int month, int year, int pageNo) {
    mHelper.setUrl('monthly');
    mHelper.getMonthlyEventList(month, year, pageNo).then((v) {
      setState(() {
        if (v.events != null) {
          print(v.events.length);
          listSize = v.events.length;
          eventList.clear();
          eventList.addAll(v.events);
          _changed(false);
        } else {
          print(v.message);
          _changed(true);
        }
      });
    });
  }

  @override
  void dispose() {
    _listScrollController.dispose();
    super.dispose();
  }

  _scrollListener() {
    print("got here");
    if (_listScrollController.position.extentAfter <= 0 && isLoading == false) {
      _getTodaysEvent(selectedDate);
    }
  }

  @override
  Widget build(BuildContext context) {
    final listView = ListView.builder(
      controller: _listScrollController,
      physics: AlwaysScrollableScrollPhysics(),
      scrollDirection: Axis.vertical,
      shrinkWrap: true,
      itemBuilder: _buildItemsForListView,
      itemCount: eventList.length,
    );
    monthHeader = monthNames[DateTime.now().month - 1] +
        ' ' +
        DateTime.now().year.toString();

    _calendarCarousel = CalendarCarousel<Event>(
      todayBorderColor: kbottomContainerColor,

      onDayPressed: (DateTime date, List<Event> events) {
        this.setState(() => _currentDate = date);
        events.forEach((event) => print(event.title));
        selectedDate = _getFormattedDate(_currentDate);
        eventList.clear();
        pageNo = 0;
        _getTodaysEvent(selectedDate);
        isMonthly = false;
        print(_currentDate);
      },

      /* rightButtonIcon: FlatButton.icon(
        onPressed: () {
          setState(() {
            _currentDate = _currentDate.add(Duration(days: 30));
            _currentMonth = DateFormat.yMMM().format(_currentDate);
            monthHeader = _currentMonth;
          });
        },
        icon: Icon(
        Icons.chevron_right,
        color: kbottomContainerColor,
      ),
        label: Text(""),
      ),
      leftButtonIcon: FlatButton.icon(
        onPressed: () {
          setState(() {
            _currentDate = _currentDate.subtract(Duration(days: 30));
            _currentMonth = DateFormat.yMMM().format(_currentDate);
            monthHeader = _currentMonth;
          });
        },
        icon: Icon(
          Icons.chevron_left,
          color: kbottomContainerColor,
        ),
        label: Text(""),
      ),*/

      daysHaveCircularBorder: null,

      showOnlyCurrentMonthDate: false,
      weekendTextStyle: TextStyle(
        color: Colors.white,
      ),
      thisMonthDayBorderColor: Colors.grey,
      weekFormat: false,
//      firstDayOfWeek: 4,
      height: 350.0,
      selectedDateTime: _currentDate,
      customGridViewPhysics: NeverScrollableScrollPhysics(),
      markedDateCustomShapeBorder:
          CircleBorder(side: BorderSide(color: Color(0xFFCA3F43))),
      markedDateCustomTextStyle: TextStyle(
        fontSize: 16.0,
        color: Color(0xFFCA3F43),
      ),
      showHeader: true,
      headerText: monthHeader,
      headerTextStyle: TextStyle(
          color: Colors.white, fontSize: 16.0, fontStyle: FontStyle.normal),
      isScrollable: false,
      todayTextStyle: TextStyle(
        color: Colors.white,
      ),
      todayButtonColor: Colors.pinkAccent,
      selectedDayTextStyle: TextStyle(
        color: Colors.white,
      ),
      weekdayTextStyle: TextStyle(color: Colors.white),
      selectedDayButtonColor: Color(0xFFCA3F43),
      selectedDayBorderColor: Colors.blue,
      daysTextStyle: TextStyle(
        color: Colors.white,
      ),
      minSelectedDate: _currentDate.subtract(Duration(days: 360)),
      maxSelectedDate: _currentDate.add(Duration(days: 360)),
      prevDaysTextStyle: TextStyle(
        fontSize: 16,
        color: Colors.white70,
      ),
      nextDaysTextStyle: TextStyle(
        fontSize: 16,
        color: Colors.white70,
      ),
      inactiveDaysTextStyle: TextStyle(
        color: Colors.tealAccent,
        fontSize: 16,
      ),
      onCalendarChanged: (DateTime date) {
        this.setState(() => _currentMonth = DateFormat.yMMM().format(date));
        monthHeader = _currentMonth;
      },
      onDayLongPressed: (DateTime date) {
        print('long pressed date $date');
      },
    );

    // TODO: implement build
    return SafeArea(
      child: Scaffold(
          body: SingleChildScrollView(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.stretch,
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                //custom icon
                Padding(
                  padding: const EdgeInsets.all(4.0),
                  child: Container(
                    width: double.infinity,
                    color: kbottomContainerColor,
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: _calendarCarousel,
                    ),
                  ),
                ),
                SizedBox(
                  height: 8.0,
                ),
                Row(mainAxisAlignment: MainAxisAlignment.spaceBetween, children: [
                  Expanded(
                    child: GestureDetector(
                      onTap: () {
                        setState(() {
                          isMonthly = false;
                          pageNo = 0;
                          eventList.clear();
                          // getList(selectedDate, pageNo);
                          _getTodaysEvent(selectedDate);
                        });
                      },
                      child: Container(
                        height: 30.0,
                        color: kbottomContainerColor,
                        child: Center(
                          child: Text(
                            "Todays",
                            textAlign: TextAlign.center,
                            style: TextStyle(
                              color: Colors.white,
                              fontSize: 16.0,
                            ),
                          ),
                        ),
                      ),
                    ),
                  ),
                  Expanded(
                    child: GestureDetector(
                      onTap: () {
                        setState(() {
                          isMonthly = true;
                          pageNo = 0;
                          getMonthlyEventList(int.parse(_currentMonth),
                              int.parse(_currentYear), pageNo);
                        });
                      },
                      child: Container(
                        height: 30.0,
                        color: Colors.white,
                        child: Center(
                          child: Text(
                            "Monthly",
                            textAlign: TextAlign.center,
                            style: TextStyle(
                              color: Colors.black,
                              fontSize: 16.0,
                            ),
                          ),
                        ),
                      ),
                    ),
                  ),
                ]),
                Container(
                  width: double.infinity,
                  child: Padding(
                    padding: const EdgeInsets.all(8.0),
                    child: isEmpty
                        ? Card(
                            color: Colors.white,
                            child: Column(
                              children: <Widget>[
                                Padding(
                                  padding:
                                      const EdgeInsets.fromLTRB(8.0, 8.0, 8.0, 0),
                                  child: Icon(
                                    FontAwesomeIcons.sadTear,
                                    color: kbottomContainerColor,
                                    size: 40.0,
                                  ),
                                ),
                                SizedBox(
                                  height: 16.0,
                                ),
                                Padding(
                                  padding: const EdgeInsets.all(8.0),
                                  child: Text(
                                    'Sorry we do not have any event on this date',
                                    style: TextStyle(
                                      color: Colors.grey.shade800,
                                      fontSize: 16.0,
                                    ),
                                  ),
                                ),
                              ],
                            ),
                          )
                        : FutureBuilder<List<Events>>(
                            builder:
                                (BuildContext context, AsyncSnapshot snapshot) {
                              switch (snapshot.connectionState) {
                                case ConnectionState.none:
                                case ConnectionState.active:
                                case ConnectionState.waiting:
                                  return CircularProgressIndicator();
                                case ConnectionState.done:
                                  if (snapshot.data != null) {
                                    isLoading = false;
                                    return listView;
                                  }
                                  break;
                              }
                            },
                            future: future,
                          ),
                  ),
                )
              ],
            ),
          )),
    );
  }

  Widget _buildItemsForListView(BuildContext context, int index) {
    if (isLoading) {
      return CircularProgressIndicator(
        backgroundColor: kbottomContainerColor,
      );
    } else {
      return Card(
        elevation: 4.0,
        color: Colors.white,
        margin: EdgeInsets.symmetric(
          vertical: 8.0,
          horizontal: 8.0,
        ),
        child: Container(
          child: ListTile(
            contentPadding:
                EdgeInsets.symmetric(horizontal: 16.0, vertical: 16.0),
            leading: Container(
              child: Text(
                '${index + 1}',
                style: TextStyle(
                  fontSize: 16.0,
                  color: Colors.grey.shade800,
                ),
              ),
            ),
            title: Text(
              eventList[index].title,
              style:
                  TextStyle(color: Colors.black, fontWeight: FontWeight.bold),
            ),
            // subtitle: Text("Intermediate", style: TextStyle(color: Colors.white)),

            subtitle: Row(
              children: <Widget>[
                Flexible(
                  child: RichText(
                    overflow: TextOverflow.ellipsis,
                    strutStyle: StrutStyle(fontSize: 12.0),
                    text: TextSpan(
                      style: TextStyle(color: Colors.grey.shade800),
                      text: eventList[index].details,
                    ),
                  ),
                ),
              ],
            ),
            trailing: Text(
              eventList[index].startTime,
              style: TextStyle(
                fontSize: 12.0,
                color: Colors.grey.shade800,
              ),
            ),
          ),
        ),
      );
    }
  }

  Widget _buildProgressIndicator() {
    return new Padding(
      padding: const EdgeInsets.all(8.0),
      child: new Center(
        child: new Opacity(
          opacity: isLoading ? 1.0 : 00,
          child: new CircularProgressIndicator(),
        ),
      ),
    );
  }

  Future<List<Events>> _getTodaysEvent(String date) async {
    isLoading = true;
    String mUrl = BASE_URL + 'events?date=$date&page=$pageNo';
    print(mUrl);
    try {
      http.Response response = await http.get(mUrl);
      print(response.statusCode);
      Map data = jsonDecode(response.body);
      if (data.containsKey('status')) {
        return null;
      } else {
        EventResult result = EventResult.fromJson(data);
        eventList.addAll(result.events);
        setState(() {
          pageNo++;
        });
        return eventList;
      }
    } catch (e) {
      print(e);
    }
    return null;
  }
}
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1 回答 1

0

使用CustomScrollView获得您想要的设计

于 2019-12-02T04:58:53.267 回答