Flutter Avatar generator snippet

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(const MaterialApp(home: AvatarPreview()));
}

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

  Color $avatarColor(String $t, Brightness $b) {
    var $h = 0;

    for (final $u in $t.trim().toUpperCase().codeUnits) {
      $h = ($h ^ $u) + (($h << 5) | ($h >> 27));
    }

    $h &= 0xFFFFFFFF;

    final $hue = ($h & 0x1FF) % 360; // 9  → 0–511 → mod 360
    const $s = 0.65;
    final $l = $b == Brightness.dark ? 0.60 : 0.50;

    return HSLColor.fromAHSL(1, $hue.toDouble(), $s, $l).toColor();
  }

  Color $textColor(Color $bg) {
    final $c = $bg.value;

    final $r = ($c >> 16) & 0xFF;
    final $g = ($c >> 8) & 0xFF;
    final $b = $c & 0xFF;

    final $lum = (54 * $r + 183 * $g + 19 * $b) >> 8;

    return $lum > 128 ? Colors.black : Colors.white;
  }

  @override
  Widget build(BuildContext context) {
    final String name = "John Doe";
    final brightness = Theme.of(context).brightness;
    final Color bgColor = $avatarColor(name, brightness);
    final Color textColor = $textColor(bgColor);

    return Scaffold(
      body: Center(
        child: CircleAvatar(
          radius: 50,
          backgroundColor: bgColor,
          child: Text(
            name.$i(),
            style: TextStyle(
              color: textColor,
              fontSize: 40,
              fontWeight: FontWeight.bold,
            ),
          ),
        ),
      ),
    );
  }
}

extension StringInitials on String {
  String $i() => trim()
      .toUpperCase()
      .split(RegExp(r'\s+'))
      .where((e) => e.isNotEmpty)
      .take(2)
      .map((e) => e.characters.first)
      .join();
}