color_background.dart

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

class ColorBackGroundView extends GetView<ColorBackgroundController> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Center(
        child: Column(
          children: [
            Obx(
              () => Container(
                width: 100,
                height: 100,
                color: controller.color.value,
              ),
            ),
            RaisedButton(
              onPressed: () {
                controller.color.value = Color(0xFFFF9000);
              },
              child: Text('change to orange'),
            ),
            RaisedButton(
              onPressed: () {
                controller.color.value = Color(0xFF459000);
              },
              child: Text('change to green'),
            ),
            RaisedButton(
              onPressed: () {
                controller.color.value = Color(0xFFFF1000);
              },
              child: Text('change to red'),
            ),
          ],
        ),
      ),
    );
  }
}

class ColorBackgroundController extends GetxController {
  Rx<Color> color = Color(0xFF42A5F5).obs;
}