flutter - 如何在 flutter 中创建交互式 flowchart

我想创建一个 flutter UI,其中有一些形状,如正方形、矩形、圆形、箭头。而且我必须能够将它们拖放到中心并在其中添加文本并将它们连接起来。我刚开始使用 flutter 所以我不知道该怎么做。谁能帮帮我吗?

回答1

使用 Draggable

例子:

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const MyStatefulWidget(),
      ),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int acceptedData = 0;

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: <Widget>[
        Draggable<int>(
          // Data is the value this Draggable stores.
          data: 10,
          feedback: Container(
            color: Colors.deepOrange,
            height: 100,
            width: 100,
            child: const Icon(Icons.directions_run),
          ),
          childWhenDragging: Container(
            height: 100.0,
            width: 100.0,
            color: Colors.pinkAccent,
            child: const Center(
              child: Text('Child When Dragging'),
            ),
          ),
          child: Container(
            height: 100.0,
            width: 100.0,
            color: Colors.lightGreenAccent,
            child: const Center(
              child: Text('Draggable'),
            ),
          ),
        ),
        DragTarget<int>(
          builder: (
            BuildContext context,
            List<dynamic> accepted,
            List<dynamic> rejected,
          ) {
            return Container(
              height: 100.0,
              width: 100.0,
              color: Colors.cyan,
              child: Center(
                child: Text('Value is updated to: $acceptedData'),
              ),
            );
          },
          onAccept: (int data) {
            setState(() {
              acceptedData += data;
            });
          },
        ),
      ],
    );
  }
}

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