flutter 下拉菜單封裝

直接上代碼，簡單的下拉菜單封裝

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_app/utils/CXColors.dart';

class DropDownSelect extends StatelessWidget {
  final String label;
  String value;
  final List<DropdownMenuItem> items;
  final ValueChanged onChanged;
  bool isText;

  DropDownSelect({Key key, this.label, this.value, this.items, this.onChanged, this.isText = false});

  @override
  Widget build(BuildContext context) {
    return new Container(
      height: 50.0,
      padding: EdgeInsets.fromLTRB(20.0, 0, 20.0, 0),
      decoration: new BoxDecoration(
        border: Border(
          bottom: BorderSide(color: CXColors.titleColor_cc, width: 0.5),
        ),
      ),
      child: Row(
        children: <Widget>[
          new Expanded(
            flex: 3,
            child: new Container(
              child: new Text(
                this.label,
                style: TextStyle(fontSize: 16.0, color: Colors.black87),
              ),
            ),
          ),
          new Expanded(
            flex: 8,
            child: Container(
              padding: EdgeInsets.only(top: 4.0),
              child: this.isText ? Text(this.value) : DropdownButton(
                icon: Icon(
                  Icons.arrow_downward,
                  color: Colors.black26,
                ),
                style: TextStyle(fontSize: 15.0, color: Colors.black54),
                iconSize: 22.0,
                isExpanded: true,
                underline: new Container(),
                hint: Text('請選擇',
                  style: TextStyle(
                      color: Colors.black26
                  ),
                ),
                items: this.items,
                onChanged: onChanged,
                value: this.value,
              ),
            ),
          ),
        ],
      ),
    );
  }
}

使用方式：

// 聲明items
List<DropdownMenuItem> _items = [
    new DropdownMenuItem(child: Text('是'), value: '是'),
    new DropdownMenuItem(child: Text('否'), value: '否'),
];
// 聲明value，默認值是否
String _value = '否';
// 使用Widget
DropDownSelect(
  label: '下拉菜單',
  items: _items,
  value: _value,
  isText: false,　　// 為true時顯示不可編輯文本，為false時顯示下拉菜單，主要用於展示和編輯
  onChanged: (T) {
    setState(() {
      _value = T;
    });
  },
),