Flutter: How can I make a Random color generator Background

Question

Generate random colors

return new RaisedButton(


    padding:  EdgeInsets.symmetric(vertical: 30.0),
    color: Colors.primaries random  List <blue,green>,

You could use: https://pub.dartlang.org/packages/random_color — knezzz, Mar 29 '19 at 12:58

score 197 · Answer 1 · edited Dec 11 '21 at 14:03

197

This is my way to get a random color:

Color((math.Random().nextDouble() * 0xFFFFFF).toInt()).withOpacity(1.0)

Note:
This import is required.

import 'dart:math' as math;

edited Dec 11 '21 at 14:03

Abhimanyu

11,351
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answered Oct 04 '18 at 03:28

Ascension

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29

for beginners: use this import statement `import 'dart:math' as math;` – Michael Hathi Jan 22 '19 at 15:04
@Ascension @Michael Hathi, what is this `import 'dart:math' as math;` doing? I see it is working without adding `math.` before `Random()` – Siddharth Mehra Apr 01 '22 at 12:45

Akbarsha · Answer 2 · 2022-11-29T11:30:59.643

94

There is an in-built list of material colors in the Colors class. You can use it like below

var generatedColor = Random().nextInt(Colors.primaries.length)
Colors.primaries[generatedColor]

example

import 'dart:math';

Icon(
    Icons.account_circle,
    size: 40,
    color: Colors.primaries[Random().nextInt(Colors.primaries.length)],
)

Above is the simplest and fastest way to colorize your list with random colors. You don't need to maintain a list of colors.

edited Nov 29 '22 at 11:30

answered Jul 15 '19 at 07:12

Akbarsha

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3

Can we get which color has been generated using this method? – Jalakam Kiran Jul 29 '20 at 19:20
2

Yes, you can. The generated random `int` decides which colour is being selected. You can use that random `int` in `local variable` and use that again to know what colour you had generated. – Akbarsha Sep 16 '20 at 06:01
can we skip the repeated color – Abdul Qadir Jul 27 '23 at 05:27

Blasanka · Accepted Answer · 2018-07-14T16:41:21.380

You can use Random class to do that:

But if you want to change the color when button is pressed, you have to use a StatefulWidget. A simple example is like below:

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

void main() {
  runApp(
    MaterialApp(
      home: MyApp(),
    ),
  );
}

class MyApp extends StatefulWidget {
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  List colors = [Colors.red, Colors.green, Colors.yellow];
  Random random = new Random();

  int index = 0;

  void changeIndex() {
    setState(() => index = random.nextInt(3));
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: RaisedButton(
        onPressed: () => changeIndex(),
        child: Text('Click'),
        color: colors[index],
      ),
    );
  }
}

Also, there is a package called random_pk by pawankumar, that will give us random color each and every time your app's build method get called.

user3044484 · Answer 4 · 2020-08-18T10:59:53.583

22

import 'dart:math';
import 'dart:ui';

class Util {
  static Color randomColor() {
    return Color(Random().nextInt(0xffffffff));
  }
}

for opaque color:

static Color randomOpaqueColor() {
  return Color(Random().nextInt(0xffffffff)).withAlpha(0xff);
}

edited Aug 18 '20 at 10:59

answered Jul 21 '19 at 14:20

user3044484

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score 7 · Answer 5 · answered Jan 12 '19 at 13:11

Another way to get tons of colors is using Random class with Color.fromARGB or Color.fromRGBO:

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

void main() {
  runApp(MaterialApp(home: MyPage()));
}

class MyPage extends StatefulWidget {
  @override
  _MyPageState createState() => new _MyPageState();
}

class _MyPageState extends State<MyPage> {
  final Random _random = Random();

  Color _color = Color(0xFFFFFFFF);

  void changeColor() {
    setState(() {
      _color = Color.fromARGB(
        //or with fromRGBO with fourth arg as _random.nextDouble(),
        _random.nextInt(256),
        _random.nextInt(256),
        _random.nextInt(256),
        _random.nextInt(256),
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: InkWell(
        onTap: changeColor,
        child: Container(
          color: _color,
        ),
      ),
    );
  }
}

If you use Color.fromRGBO:

Fourth argument should be within 0.0 to 1.0 and fortunately we have _random.nextDouble() that gives a value between 0.0 to 1.0 randomly.

By the way:

R - Red
B - Blue
G - Green
O - Opacity
A - Alpha

Andrew · Answer 6 · 2019-09-07T10:43:42.723

7

To get random color I do the next:

import 'dart:math' as math;

final rnd = math.Random();

Color getRandomColor() => Color(rnd.nextInt(0xffffffff));

edited Sep 07 '19 at 10:43

answered Sep 07 '19 at 10:29

Andrew

36,676
11
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score 5 · Answer 7 · answered Jul 20 '18 at 14:06

This will generate a different color for the button everytime the build method for the app is called

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

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

    class MyApp extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
      // TODO: implement build
        return new MaterialApp(
            title: "Raised Button",
            theme: new ThemeData(
               primarySwatch: Colors.teal,
            ),
            home: new HomePage());
      }
    }

    class HomePage extends StatefulWidget {
      @override
      HomePageState createState() => new HomePageState();
    }

    class HomePageState extends State<HomePage> {
      //contains the colours for the circle Avatars
      final List<Color> circleColors = [Colors.red, Colors.blue, Colors.green];

      Color randomGenerator() {
        return circleColors[new Random().nextInt(2)];
      }

      @override
      Widget build(BuildContext context) {
        return Center(
          child: RaisedButton(
            onPressed: () => {},
            child: Text('Click'),
            color: randomGenerator(),
          ),
        );
      }
  }

Jeison · Answer 8 · 2021-03-05T20:35:49.630

5

In this way below you can obtain a random color with a one line command without needing any import:

 ([...Colors.primaries]..shuffle()).first

This is also a great example of cascade notation and spread operators in dart. Here you can find more information about it.

edited Mar 05 '21 at 20:35

answered Mar 05 '21 at 19:56

Jeison

71
1
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score 3 · Answer 9 · answered Apr 13 '20 at 10:18

We can use random class for that But there is a random_color plugin in the flutter that can help us for generating random color and also we can select high saturation colors with this code:

import 'package:random_color/random_color.dart';

RandomColor _randomColor = RandomColor();

Color _color = _randomColor.randomColor(
  colorSaturation: ColorSaturation.highSaturation
);

And light colors with this code:

import 'package:random_color/random_color.dart';

RandomColor _randomColor = RandomColor();

Color _color = _randomColor.randomColor(
  colorBrightness: ColorBrightness.light
);

For more options read this https://pub.dev/packages/random_color#-readme-tab-

score 2 · Answer 10 · answered Dec 15 '20 at 19:41

I think we need a separate class for that (you can use static or top-level functions).

Just don't forget that nextInt: "Generates a non-negative random integer uniformly distributed in the range from 0, inclusive, to max, exclusive.". So set "max" to 0x100000000 (0xFFFFFFFF + 1)!

import 'dart:math';

import 'package:flutter/cupertino.dart';

class RandomColor {
  static const _MAX_VALUE = 0x100000000;
  final _random = Random();

  Color nextColor() => Color(_random.nextInt(_MAX_VALUE));
}

score 1 · Answer 11 · answered Jun 21 '21 at 20:18

Well if you want distinguishable colors , this method gives 4096 different color with at least 16 level difference :

var rnd = Random();
var r = rnd.nextInt(16) * 16;
var g = rnd.nextInt(16) * 16;
var b = rnd.nextInt(16) * 16;
Color color = Color.fromARGB(255, r, g, b);

score 1 · Answer 12 · answered Sep 26 '22 at 08:07

If we want to pick random colors from the Colors.primary class:

1- import:

import 'dart:math' as math show Random;

2- Set value:

final color = Colors.primaries[math.Random().nextInt(Colors.primaries.length)];

3- Use value:

backgroundColor: color,

score 0 · Answer 13 · answered May 28 '19 at 16:34

Simplest and best suggested way to do this is:

Step 1: Add dependency in pubspec.yaml random_color: ^1.0.3

Step 2: Add import import 'package:random_color/random_color.dart';

Step 3: In "color" attribute write color: RandomColor().randomColor();

score 0 · Answer 14 · answered Mar 09 '23 at 18:16

I do the easiest way,

import 'dart:math';

and then I use container as avatar

             Container(
                height: 100,
                width: 100,
                decoration: BoxDecoration(
                  borderRadius: BorderRadius.circular(100),
                  color: Color.fromRGBO(
                    random.nextInt(255),
                    random.nextInt(255),
                    random.nextInt(255),
                    1,
                  ),
                ),
                child: const Icon(Icons.person, size: 60),
              )

Juned Raza · Answer 15 · 2022-04-28T07:49:45.763

-1

Try Using Package for Gmail Like effect. It will generate random color background. Also support selection widget

RoundedImageWithTextAndBG(
    radius: 20,
    isSelected: isSelected,
    uniqueId: textModel[widget.index]['uniqueId'],
    image: (widget.index % 3 == 0)
        ? 'https://picsum.photos/id/${widget.index}/800/800'
        : '',
    text: textModel[widget.index]['name'],
  ),

edited Apr 28 '22 at 07:49

answered Apr 28 '22 at 06:37

Juned Raza

228
3
6

Flutter: How can I make a Random color generator Background

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