Flutter着色背景ExpansionPanelList

import 'package:flutter/material.dart';

class MyExpansionPanelList extends StatefulWidget {
  @override
  _MyExpansionPanelListState createState() => _MyExpansionPanelListState();
}

class _MyExpansionPanelListState extends State<MyExpansionPanelList> {
  List<Item> _items = generateItems(5);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Expansion Panel List'),
      ),
      body: SingleChildScrollView(
        child: Container(
          padding: EdgeInsets.all(16.0),
          child: ExpansionPanelList(
            elevation: 1,
            expandedHeaderPadding: EdgeInsets.all(0),
            expansionCallback: (int index, bool isExpanded) {
              setState(() {
                _items[index].isExpanded = !isExpanded;
              });
            },
            children: _items.map<ExpansionPanel>((Item item) {
              return ExpansionPanel(
                headerBuilder: (BuildContext context, bool isExpanded) {
                  return ListTile(
                    title: Text(item.headerValue),
                  );
                },
                body: ListTile(
                  title: Text(item.expandedValue),
                ),
                isExpanded: item.isExpanded,
              );
            }).toList(),
          ),
        ),
      ),
    );
  }
}

class Item {
  Item({
    required this.expandedValue,
    required this.headerValue,
    this.isExpanded = false,
  });

  String expandedValue;
  String headerValue;
  bool isExpanded;
}

List<Item> generateItems(int numberOfItems) {
  return List<Item>.generate(numberOfItems, (int index) {
    return Item(
      headerValue: 'Panel $index',
      expandedValue: 'This is item number $index',
    );
  });
}

void main() {
  runApp(MyExpansionPanelList());
}