content: import 'package:flutter/material.dart';
  
  void main() {
    runApp(MaterialApp(
      title: 'Checkbox Widget Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(title: Text('Checkbox Widget Example'),),
        body: MyApp(),
      )
    ));
  }
  
  class MyApp extends StatefulWidget {
    @override
    _MyAppState createState() => _MyAppState();
  }
  
  class _MyAppState extends State<MyApp> {
  
    bool _cValue = false;
  
    @override
    Widget build(BuildContext context) {
      return Padding(
        padding: const EdgeInsets.all(16.0),
        child: Container(
          decoration: BoxDecoration(
            border: Border.all(color: Colors.purple)
          ),
          child: Transform.scale(
            scale: 2.0,
            child: Checkbox(
              value: _cValue,
              onChanged: (staus){
                print(staus);
                setState(() {
                  _cValue = staus;
                });
              },
              activeColor: Colors.purple,
              checkColor: Colors.red,
              tristate: true,
            ),
          ),
        ),
      );
    }
  }
  
  