import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      home: Scaffold(body: BugWidget()),
    ),
  );
}

class BugWidget extends StatefulWidget {
  @override
  _BugWidgetState createState() => _BugWidgetState();
}

class _BugWidgetState extends State<BugWidget> {
  final photoURL = "https://gravatar.com/avatar/11ef7c4b9749807b121e74cd353be3eb";
  var radius = 20.0;
  var toggleForegroundImage = false;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        CircleAvatar(
          radius: radius,
          foregroundImage:
              toggleForegroundImage ? NetworkImage(photoURL) : null,
        ),
        TextButton(
          onPressed: () {
            setState(() {
              radius = radius == 20 ? 40 : 20;
            });
          },
          child: Text('toggle Radius'),
        ),
        TextButton(
          onPressed: () {
            setState(() {
              toggleForegroundImage = !toggleForegroundImage;
            });
          },
          child: Text('toggle ForegroundImage'),
        ),
      ],
    );
  }
}