List view with Parent child relationship and checkboxes selection upto three or N level in Flutter

Akash
June 24, 2023
234 views
0 votes
2 Answers

I want to achieve tree hierarchy list view

i have tried few reference as i got dev.pub bellow are,

https://pub.dev/packages/parent_child_checkbox

i have seen but i cannot see as per i need 3 level of sub tree with check box image state and selection according see below image i want to achieve,
Any one idea how to achieve or guild please share…
Thank you….

Tags: flutter flutter-dependencies

Answers

Maybe you can create your own renderObject, I try my best for make the indent widget look like your image provided. Keep in mind this is not Sliver widget therefore this can cost some perform an issue.

also I suggest you take a look this video if youe interest about renderObject in flutter.
https://www.youtube.com/watch?v=HqXNGawzSbY&t=7458s

main.dart

import 'package:flutter/material.dart';
import 'indent_widget.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  Widget _buildColumn() {
    return Row(
      children: [
        Checkbox(value: false, onChanged: (value) {}),
        const Expanded(child: Text('text'))
      ],
    );
  }

  @override
  Widget build(BuildContext context) {
    double tabSpace = 30;
    return Scaffold(
      body: SafeArea(
        child: SingleChildScrollView(
          child: IndentWidget(children: [
            _buildColumn(),
            IndentTab(
                tabSpace: tabSpace,
                child: IndentWidget(
                  children: [
                    IndentTab(
                        tabSpace: tabSpace,
                        child: IndentWidget(
                          children: [
                            _buildColumn(),
                            _buildColumn(),
                            IndentTab(
                                tabSpace: tabSpace,
                                child: IndentWidget(
                                  children: [
                                    _buildColumn(),
                                    _buildColumn(),
                                    IndentTab(
                                        tabSpace: tabSpace,
                                        child: IndentWidget(
                                          children: [
                                            _buildColumn(),
                                            _buildColumn(),
                                            _buildColumn(),
                                          ],
                                        )),
                                    _buildColumn(),
                                    IndentTab(
                                        tabSpace: tabSpace,
                                        child: IndentWidget(
                                          children: [
                                            _buildColumn(),
                                            _buildColumn(),
                                            _buildColumn(),
                                          ],
                                        )),
                                  ],
                                )),
                            _buildColumn(),
                          ],
                        )),
                    _buildColumn(),
                    _buildColumn(),
                    _buildColumn(),
                  ],
                )),
            _buildColumn(),
          ]),
        ),
      ),
    );
  }
}

indent_widget.dart

import 'dart:math';

import 'package:flutter/cupertino.dart';
import 'package:flutter/rendering.dart';

class IndentWidget extends MultiChildRenderObjectWidget {
  IndentWidget({super.key, super.children});

  @override
  RenderObject createRenderObject(BuildContext context) {
    /// 1. entry point.
    return RenderIndent();
  }
}

/// provide information to RenderIndent;
class RenderIndentParentData extends ContainerBoxParentData<RenderBox> {
  double? tabSpace;
}

class IndentTab extends ParentDataWidget<RenderIndentParentData> {
  final double tabSpace;

  const IndentTab({super.key, required this.tabSpace, required super.child});

  @override
  void applyParentData(RenderObject renderObject) {
    final RenderIndentParentData parentData =
        renderObject.parentData! as RenderIndentParentData;

    if (parentData.tabSpace != tabSpace) {
      parentData.tabSpace = tabSpace;
      final targetObject = renderObject.parent;
      if (targetObject is RenderObject) {
        targetObject.markNeedsLayout();
      }
    }
  }

  @override
  Type get debugTypicalAncestorWidgetClass => RenderIndentParentData;
}

class RenderIndent extends RenderBox
    with
        ContainerRenderObjectMixin<RenderBox, RenderIndentParentData>,
        RenderBoxContainerDefaultsMixin<RenderBox, RenderIndentParentData> {
  @override
  void setupParentData(RenderBox child) {
    if (child.parentData is! RenderIndentParentData) {
      child.parentData = RenderIndentParentData();
    }
  }

  Size _performLayout(BoxConstraints constraints, bool dry) {
    RenderBox? child = firstChild;
    double width = 0, height = 0;

    while (child != null) {
      final RenderIndentParentData childParentData =
          child.parentData as RenderIndentParentData;
      final double leftShift = childParentData.tabSpace ?? 0;

      if (!dry) {
        childParentData.offset = Offset(leftShift, height);
        child.layout(BoxConstraints(maxWidth: constraints.maxWidth),
            parentUsesSize: true);
      }
      height += child.size.height;
      width = max(width, leftShift + child.size.width);
      child = childParentData.nextSibling;
    }

    if (width > constraints.maxWidth) {
      width = constraints.maxWidth;
    }

    return Size(width, height);
  }

  @override
  void performLayout() {
    size = _performLayout(constraints, false);
  }

  @override
  Size computeDryLayout(BoxConstraints constraints) {
    return _performLayout(constraints, true);
  }

  @override
  void paint(PaintingContext context, Offset offset) {
    defaultPaint(context, offset);
  }

  @override
  bool hitTestChildren(BoxHitTestResult result, {required Offset position}) {
    return defaultHitTestChildren(result, position: position);
  }
}

You should have a recursive data like this:

final list = [
  {
    "title": "title1",
    "list": [
      {
        "title": "title11",
        "list": [
          {
            "title": "title111",
            "list": <Map<String, dynamic>>[],
          },
          {
            "title": "title112",
          },
        ],
      },
      {
        "title": "title12",
        "list": <Map<String, dynamic>>[],
      },
      {
        "title": "title13",
        "list": <Map<String, dynamic>>[],
      },
      {
        "title": "title14",
        "list": <Map<String, dynamic>>[],
      },
    ],
  },
  {
    "title": "title2",
    "list": [
      {
        "title": "title21",
        "list": <Map<String, dynamic>>[],
      },
      {
        "title": "title22",
        "list": <Map<String, dynamic>>[
          {
            "title": "title221",
            "list": [
              {
                "title": "title2211",
                "list": <Map<String, dynamic>>[],
              },
              {
                "title": "title2212",
                "list": <Map<String, dynamic>>[],
              },
            ],
          },
          {
            "title": "title222",
            "list": [
              {
                "title": "title2221",
                "list": <Map<String, dynamic>>[],
              },
              {
                "title": "title2222",
                "list": <Map<String, dynamic>>[],
              },
            ],
          },
        ],
      },
      {
        "title": "title23",
        "list": <Map<String, dynamic>>[],
      },
    ],
  },
];

To Show this data as a recursive list in UI, you should build a Recursive Widget, firstly we build a CheckBoxTitle widget that its checkBox can be selected like this:

class CheckBoxTitle extends StatefulWidget {
  const CheckBoxTitle({
    Key? key,
    required this.title,
    required this.level,
  }) : super(key: key);

  final String title;
  final int level;

  @override
  State<CheckBoxTitle> createState() => _CheckBoxTitleState();
}

class _CheckBoxTitleState extends State<CheckBoxTitle> {
  bool _checkBoxValue = false;

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        SizedBox(
          width: widget.level * 16,
        ),
        Checkbox(
          value: _checkBoxValue,
          onChanged: (value) {
            setState(() {
              _checkBoxValue = value!;
            });
          },
        ),
        Expanded(
          child: FittedBox(
            fit: BoxFit.scaleDown,
            alignment: AlignmentDirectional.centerStart,
            child: Text(
              widget.title,
            ),
          ),
        ),
      ],
    );
  }
}

then we build our recursive Widget:


class RecursiveListView extends StatelessWidget {
  const RecursiveListView({
    Key? key,
    required this.listOfMap,
    this.level = 0,
  }) : super(key: key);

  final List<Map<String, dynamic>> listOfMap;
  final int level;

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: listOfMap.length,
      itemBuilder: (context, index) {
        final map = listOfMap[index];

        List<Map<String, dynamic>>? innerList =
            map["list"] as List<Map<String, dynamic>>?;

        return ExpansionTile(
          trailing:
              (innerList?.isEmpty ?? true) ? const SizedBox.shrink() : null,
          title: ListTile(
            title: CheckBoxTitle(
              title: map["title"] as String,
              level: level,
            ),
          ),
          children: [
            if (innerList?.isNotEmpty ?? false)
              RecursiveListView(
                listOfMap: innerList!,
                level: level + 1,
              ),
          ],
        );
      },
      physics: level == 0 ? null : const NeverScrollableScrollPhysics(),
      shrinkWrap:
          level != 0, // to make the list fill the entire screen at level 0
    );
  }
}

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