Generate a color gradient grid in Flutter

color_gradient_grid.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(body: ColorGrid()),
    );
  }
}

class ColorGrid extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final colorA = Colors.green;
    final colorB = Colors.blueGrey;
    final colorC = Colors.lightGreenAccent;
    final colorD = Colors.greenAccent;

    final numRows = 10;
    final numCols = 10;

    final h = MediaQuery.of(context).size.height / numCols;
    final w = MediaQuery.of(context).size.width / numRows;

    int interpolate(int a, int b, int c, int d, double t, double s) {
      return (a * (1 - t) * (1 - s) +
              b * t * (1 - s) +
              c * (1 - t) * s +
              d * t * s)
          .floor();
    }

    Widget Function(int) generator2(double t) {
      return (int index) {
        final s = index / numCols;

        return Container(
          color: Color.fromRGBO(
            interpolate(colorA.red, colorB.red, colorC.red, colorD.red, t, s),
            interpolate(
                colorA.green, colorB.green, colorC.green, colorD.green, t, s),
            interpolate(
                colorA.blue, colorB.blue, colorC.blue, colorD.blue, t, s),
            1.0,
          ),
          height: h,
          width: w,
        );
      };
    }

    Widget generator(int index) {
      final t = index / numRows;
      return Row(
        children: List<Widget>.generate(numCols, generator2(t)),
      );
    }

    return Column(
      children: List<Widget>.generate(numRows, generator),
    );
  }
}