how to change layout in Flutter

Question

I've been trying to design the layout of my ExpansionTile just like the design below but I couldn't figure out how to change the layout. any suggestion on how to change the border radius, change the background color and also make a gap between each other?.

I tried adding boxDecoration in each container but the style only apply to outside but not on each expansionTile.

import 'package:flutter/material.dart';

class MyReoderWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ReorderItems(topTen: ['j']);
  }
}
class DataHolder {
  List<String> parentKeys;

  Map<String, List<String>> childMap;

  DataHolder._privateConstructor();

  static final DataHolder _dataHolder = DataHolder._privateConstructor();

  static DataHolder get instance => _dataHolder;

  factory DataHolder.initialize({@required parentKeys}) {
    _dataHolder.parentKeys = parentKeys;
    _dataHolder.childMap = {};
    for (String key in parentKeys) {
      _dataHolder.childMap.putIfAbsent(

    }
    return _dataHolder;
  }
}

class ReorderItems extends StatefulWidget {
  final List<String> topTen;
  ReorderItems({this.topTen});
  @override
  _ReorderItemsState createState() => _ReorderItemsState();
}

class _ReorderItemsState extends State<ReorderItems> {
  @override
  void initState() {
    super.initState();
    // initialize the children for the Expansion tile
    // This initialization can be replaced with any logic like network fetch or something else.
    DataHolder.initialize(parentKeys: widget.topTen);
  }

  @override
  Widget build(BuildContext context) {
    return PrimaryScrollController(
      key: ValueKey(widget.topTen.toString()),
      controller: ScrollController(),
      child: Container(
        decoration: BoxDecoration(),
        child: ReorderableListView(
          onReorder: onReorder,
          children: getListItem(),
        ),
      ),
    );
  }

  List<ExpansionTile> getListItem() => DataHolder.instance.parentKeys
      .asMap()
      .map((index, item) => MapEntry(index, buildTenableListTile(item, index)))
      .values
      .toList();

  ExpansionTile buildTenableListTile(String mapKey, int index) => ExpansionTile(
        key: ValueKey(mapKey),
        title: Text(mapKey),
        leading: Icon(Icons.list),
        children: [
          Container(
            decoration: BoxDecoration(
              borderRadius: BorderRadius.all(Radius.circular(20))
            ),
            key: ValueKey('$mapKey$index'),
            height: 200,
            child: Container(
              padding: EdgeInsets.only(left: 30.0),
              child: ReorderList(
                parentMapKey: mapKey,
              ),
            ),
          ),
        ],
      );

  void onReorder(int oldIndex, int newIndex) {
    if (newIndex > oldIndex) {
      newIndex -= 1;
    }
    setState(() {
      String game = widget.topTen[oldIndex];
      DataHolder.instance.parentKeys.removeAt(oldIndex);
      DataHolder.instance.parentKeys.insert(newIndex, game);
    });
  }
}

class ReorderList extends StatefulWidget {
  final String parentMapKey;
  ReorderList({this.parentMapKey});
  @override
  _ReorderListState createState() => _ReorderListState();
}

class _ReorderListState extends State<ReorderList> {
  @override
  Widget build(BuildContext context) {
    return PrimaryScrollController(
      controller: ScrollController(),
      child: ReorderableListView(
        // scrollController: ScrollController(),
        onReorder: onReorder,
        children: DataHolder.instance.childMap[widget.parentMapKey]
            .map(
              (String child) => Container(
                child: ListTile(
                  key: ValueKey(child),
                  leading: Icon(Icons.list),
                  title: Text(child),
                ),
              ),
            )
            .toList(),
      ),
    );
  }

  void onReorder(int oldIndex, int newIndex) {
    if (newIndex > oldIndex) {
      newIndex -= 1;
    }
    List<String> children = DataHolder.instance.childMap[widget.parentMapKey];
    String game = children[oldIndex];
    children.removeAt(oldIndex);
    children.insert(newIndex, game);
    DataHolder.instance.childMap[widget.parentMapKey] = children;
    // Need to set state to rebuild the children.
    setState(() {});
  }
}

Answer 1

You can do it using custom expandable container.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Calendar',
      theme: ThemeData(
        primarySwatch: Colors.grey,
      ),
      debugShowCheckedModeBanner: false,
      home: Material(
        child: MyReoderWidget(),
      ),
    );
  }
}

class CustomModel {
  String title;
  bool isExpanded;
  List<String> subItems;

  CustomModel({this.title, this.subItems, this.isExpanded = false});
}

class MyReoderWidget extends StatefulWidget {
  @override
  _MyReoderWidgetState createState() => _MyReoderWidgetState();
}

class _MyReoderWidgetState extends State<MyReoderWidget> {
  List<CustomModel> listItems;

  @override
  void initState() {
    super.initState();
    listItems = List<CustomModel>();
    listItems.add(CustomModel(
        title: "App Name 1", subItems: ["Card Name 1", "Card Name 2"]));
    listItems.add(CustomModel(
        title: "App Name 2", subItems: ["Card Name 3", "Card Name 4"]));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      body: ListView(
          children: listItems
              .map((model) => new Padding(
                    padding: EdgeInsets.only(
                      bottom: 10,
                    ),
                    child: ExpandableCardContainer(
                      isExpanded: model.isExpanded,
                      collapsedChild: createHeaderCard(model),
                      expandedChild: Column(
                        children: <Widget>[
                          Padding(
                            padding: EdgeInsets.only(
                              bottom: 10,
                            ),
                            child: createHeaderCard(model),
                          )
                        ]..addAll(model.subItems
                            .map((e) => createChildCard(e))
                            .toList()),
                      ),
                    ),
                  ))
              .toList()),
    );
  }

  Widget createHeaderCard(CustomModel model) {
    return Container(
      child: Row(
        children: <Widget>[
          Icon(
            Icons.more_vert,
            color: Colors.white,
          ),
          Expanded(
            child: Text(
              model.title,
              style: TextStyle(color: Colors.white),
            ),
          ),
          GestureDetector(
            onTap: () {
              setState(() {
                model.isExpanded = !model.isExpanded;
              });
            },
            child: Icon(
              model.isExpanded
                  ? Icons.keyboard_arrow_up
                  : Icons.keyboard_arrow_down,
              color: Colors.white,
            ),
          )
        ],
      ),
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(10),
        color: Color(0xFF132435),
      ),
      height: 50,
    );
  }

  Widget createChildCard(String subItems) {
    return Container(
      margin: EdgeInsets.only(left: 30, bottom: 10),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          Icon(
            Icons.more_vert,
            color: Colors.white,
          ),
          Expanded(
            child: Text(
              subItems,
              style: TextStyle(color: Colors.white),
            ),
          ),
        ],
      ),
      decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(10),
        color: Color(0xFF132435),
      ),
      height: 50,
    );
  }
}

class ExpandableCardContainer extends StatefulWidget {
  final bool isExpanded;
  final Widget collapsedChild;
  final Widget expandedChild;

  const ExpandableCardContainer(
      {Key key, this.isExpanded, this.collapsedChild, this.expandedChild})
      : super(key: key);

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

class _ExpandableCardContainerState extends State<ExpandableCardContainer> {
  @override
  Widget build(BuildContext context) {
    return new AnimatedContainer(
      duration: new Duration(milliseconds: 200),
      curve: Curves.easeInOut,
      child: widget.isExpanded ? widget.expandedChild : widget.collapsedChild,
    );
  }
}