Dynamic Text Color Based on Background Brightness in Flutter

Output Screenshot

SOLUTION
1. The computeLuminance() method from the Color class.

Text(
                'Hello',
                style: TextStyle(
                    fontSize: 80,
                    color: _backgroundColor.computeLuminance() > 0.5
                        ? Colors.black
                        : Colors.white),
              ),

2. The estimateBrightnessForColor() method from the ThemeData class.


Text(
                'Hello',
                style: TextStyle(
                    fontSize: 80,
                    color: ThemeData.estimateBrightnessForColor(_bgColor) ==
                            Brightness.light
                        ? Colors.black
                        : Colors.white),
              ),

The Complete Code
// main.dart

import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      // Remove the debug banner
      debugShowCheckedModeBanner: false,
      title: 'Kindacode.com',
      home: HomePage(),
    );
  }
}

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

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

class _HomePageState extends State<HomePage> {
  // Background color of the box
  // In the beginning, it is blue
  Color _bgColor = Colors.blue;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Kindacode.com'),
      ),
      body: Column(
        children: [
          const SizedBox(
            height: 50,
          ),
          Container(
            width: 300,
            height: 300,
            color: _bgColor,
            child: Center(
              child: Text(
                'Hello',
                style: TextStyle(
                    fontSize: 80,
                    color: _bgColor.computeLuminance() > 0.5
                        ? Colors.black
                        : Colors.white),
              ),
            ),
          ),
          const SizedBox(
            height: 50,
          ),

          // The buttons below used to change the box color
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceAround,
            children: [
              // Green Acent
              MaterialButton(
                onPressed: () {
                  setState(() {
                    _bgColor = Colors.greenAccent;
                  });
                },
                color: Colors.greenAccent,
              ),

              // Orange
              MaterialButton(
                onPressed: () {
                  setState(() {
                    _bgColor = Colors.orange;
                  });
                },
                color: Colors.orange,
              ),

              // Yellow
              MaterialButton(
                onPressed: () {
                  setState(() {
                    _bgColor = Colors.yellow;
                  });
                },
                color: Colors.yellow,
              ),

              // Black
              MaterialButton(
                onPressed: () {
                  setState(() {
                    _bgColor = Colors.black;
                  });
                },
                color: Colors.black,
              )
            ],
          )
        ],
      ),
    );
  }
}

Full Summary:
Step1: assign variable

` Color _bgColor = Colors.blue;

@override
Widget build(BuildContext context) `

Step2:For upper image
body: Column----Container---child: Center-----child: Text

Step3:For below image
row(MainAxisAlignment.spaceAround)---children---four materialButton--- step 4:inside materialButton---set _bgColor = Colors.yellow
Refrence
Click here

Debug School

Dynamic Text Color Based on Background Brightness in Flutter

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