flutter-sport/lib/widgets/city_picker.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:sport/widgets/city_picker_data.dart';


Future<CityResult> showCityPicker(
    BuildContext context, {
      CityResult initCity,
    }) async {
  Completer<CityResult> completer = Completer();
  var cityData = await loadCityData();

  var result = showDialog(
    context: context,
    builder: (c) => CityPicker(
      params: cityData,
      initResult: initCity,
    ),
  );

  result.then((v) {
    completer.complete(v);
  });

  return completer.future;
}

class CityPicker extends StatefulWidget {
  final Map<String, dynamic> params;
  final CityResult initResult;
  const CityPicker({
    Key key,
    this.params,
    this.initResult,
  }) : super(key: key);

  @override
  _CityPickerState createState() => _CityPickerState();
}

class _CityPickerState extends State<CityPicker> {
  int provinceIndex = 0;
  int cityIndex = 0;
  int countyIndex = 0;

  var cityResult = CityResult();

  Map<String, dynamic> get datas => widget.params;

  List<dynamic> get provinceList => datas["provinceList"];
  String proviceNameByIndex(int index) => provinceList[index]["name"];

  List<dynamic> get cityList => provinceList[provinceIndex]["cityList"];

  List<dynamic> get countyList => cityList[cityIndex]["countyList"];

  FixedExtentScrollController provinceScrollController;
  FixedExtentScrollController cityScrollController;
  FixedExtentScrollController countyScrollController;

  @override
  void initState() {
    super.initState();

    var initResult = widget.initResult;
    List<int> initItems =
    findIndexs(initResult?.province, initResult?.city, initResult?.county);

    _log(initItems);

    provinceScrollController =
        FixedExtentScrollController(initialItem: initItems[0]);
    cityScrollController =
        FixedExtentScrollController(initialItem: initItems[1]);
    countyScrollController =
        FixedExtentScrollController(initialItem: initItems[2]);

    cityResult.province = proviceNameByIndex(0);
    cityResult.city = cityList[0]["name"];
    cityResult.county = countyList[0]["name"];

    provinceIndex = initItems[0];
    cityIndex = initItems[1];
    countyIndex = initItems[2];
  }

  @override
  void dispose() {
    provinceScrollController?.dispose();
    cityScrollController?.dispose();
    countyScrollController?.dispose();
    super.dispose();
  }

  String provinceByIndex(int index) {
    return provinceList[index]["name"];
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
              contentPadding: EdgeInsets.all(6.0),
              shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
              content: Container(
                width: 300,
                height: 200,
                child: Column(
                  children: <Widget>[
                    Row(
                      children: <Widget>[
                        IconButton(onPressed: () {
                          Navigator.of(context).pop();
                        }, icon: Text("取消")),
                        Expanded(
                            child: Center(
                                child: Text(
                                  "选择地区",
                                  style: Theme.of(context).textTheme.headline3,
                                ))),
                        IconButton(
                            onPressed: () {
                              cityResult.province = proviceNameByIndex(provinceIndex);
                              cityResult.provinceCode = provinceList[provinceIndex]["no"].padRight(6, '0');
                              cityResult.city = cityList[cityIndex]["name"];
                              cityResult.cityCode = cityList[cityIndex]["no"].padRight(6, '0');
                              cityResult.county = countyList[countyIndex]["name"];
                              cityResult.countyCode = countyList[countyIndex]["no"].padRight(6, '0');
                              Navigator.pop(context, cityResult);
                            },
                            icon: Text(
                              "确认",
                              style: Theme.of(context).textTheme.subtitle1.copyWith(color: Theme.of(context).accentColor),
                            )),
                      ],
                    ),
                    Divider(),
                    _buildPickers(),
                  ],
                ),
              ),
            );
  }

  Widget _buildButtons() {
    Widget buildButton(String text, Function onTap) {
      return CupertinoButton(
        child: Text(text),
        onPressed: onTap,
      );
    }

    return Container(
      color: Colors.white,
      height: 40.0,
      child: Row(
        children: <Widget>[
          buildButton("取消", () {
            Navigator.pop(context);
          }),
          Expanded(
            child: Container(),
          ),
          buildButton("确定", () {
            cityResult.province = proviceNameByIndex(provinceIndex);
            cityResult.provinceCode = provinceList[provinceIndex]["no"].padRight(6, '0');
            cityResult.city = cityList[cityIndex]["name"];
            cityResult.cityCode = cityList[cityIndex]["no"].padRight(6, '0');
            cityResult.county = countyList[countyIndex]["name"];
            cityResult.countyCode = countyList[countyIndex]["no"].padRight(6, '0');
            Navigator.pop(context, cityResult);
          }),
        ],
      ),
    );
  }

  Widget _buildPickers() {
    return Expanded(
      child: Row(
        children: <Widget>[
          Expanded(child: buildProvincePicker()),
          Expanded(child: buildCityPicker()),
          // Expanded(child: buildCountyPicker()),
        ],
      ),
    );
  }

  Widget buildProvincePicker() {
    return CupertinoPicker.builder(
      itemExtent: 40,
      scrollController: provinceScrollController,
      backgroundColor: Colors.white,
      onSelectedItemChanged: onProvinceChanged,
      itemBuilder: _buildProvinceItem,
      childCount: provinceList.length,
    );
  }

  Widget _buildProvinceItem(BuildContext context, int index) {
    var name = provinceList[index]["name"];
    return _buildTextItem(name);
  }

  Widget buildCityPicker() {
    _log("_build city picker");
    return CupertinoPicker.builder(
      key: ValueKey(this.cityList),
      itemExtent: 40,
      scrollController: cityScrollController,
      backgroundColor: Colors.white,
      onSelectedItemChanged: onCityChanged,
      itemBuilder: _buildCityItem,
      childCount: cityList.length,
    );
  }

  Widget _buildCityItem(BuildContext context, int index) {
    var name = cityList[index]["name"];
    return _buildTextItem(name);
  }

  Widget buildCountyPicker() {
    _log("_build county picker");
    return CupertinoPicker.builder(
      key: ValueKey(this.countyList),
      itemExtent: 40,
      scrollController: countyScrollController,
      backgroundColor: Colors.white,
      onSelectedItemChanged: onCountyChanged,
      itemBuilder: _buildCountyItem,
      childCount: countyList.length,
    );
  }

  Widget _buildCountyItem(BuildContext context, int index) {
    var name = countyList[index]["name"];
    _log("county $index name = $name");
    return _buildTextItem(name);
  }

  Widget _buildTextItem(String text) {
    return Container(
      color: Colors.white,
      alignment: Alignment.center,
      padding: const EdgeInsets.symmetric(horizontal: 5.0),
      child: Text(
        text,
        textAlign: TextAlign.center,
        style: const TextStyle(fontSize: 14.0),
      ),
    );
  }

  void onProvinceChanged(int value) {
    _log("onProvinceChanged value = $value");
    provinceIndex = value;
    cityIndex = 0;
    countyIndex = 0;
    cityResult.province = proviceNameByIndex(value);
    cityResult.city = cityList[0]["name"];
    cityResult.county = countyList[0]["name"];
    cityScrollController.jumpTo(0);
    // countyScrollController.jumpTo(0);

    cityScrollController = FixedExtentScrollController(initialItem: 0);
    countyScrollController = FixedExtentScrollController(initialItem: 0);

    setState(() {});
  }

  void onCityChanged(int value) {
    _log("onCityChanged value = $value");
    cityIndex = value;
    countyIndex = 0;
    cityResult.city = cityList[value]["name"];
    cityResult.county = countyList[0]["name"];

    countyScrollController = FixedExtentScrollController(initialItem: 0);
    setState(() {});
  }

  void onCountyChanged(int value) {
    _log("onCountyChanged value = $value");
    countyIndex = value;
    cityResult.county = countyList[value]["name"];
    setState(() {});
  }
}

void _log(msg) {
  // print(msg);
}