import 'dart:typed_data';
import 'dart:ui';

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {

  @override
  void initState() {
  super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      showPerformanceOverlay: true,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),

    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key}) : super(key: key);
  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
  final screenshotKey = GlobalKey();

  Future<Uint8List> takeScreenshot({
    int width = 350,
    int height = 350
  }) async {
    // Wait a bit so the tree is mounted
    await Future.delayed(const Duration(milliseconds: 20), () {});
    final boundary = screenshotKey.currentContext?.findRenderObject() as RenderRepaintBoundary;
    var image = await boundary.toImage(pixelRatio: 3);
    print('DBUG: image.toByteData fails on iOS');
    var byteData = await image.toByteData(format: ImageByteFormat.png);
    print('DBUG: This log is never printed on iOS');
    Uint8List pngBytes = byteData!.buffer.asUint8List();
    return pngBytes;
  }

  @override
  Widget build(BuildContext context) {
    takeScreenshot();
    return MaterialApp(
      title: 'Impeller Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Impeller Demo'),
        ),
        body: Center(
            child: RepaintBoundary(
              key: screenshotKey,
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Expanded(
                      child: Container(
                          color: Colors.black45
                    )
                 ),
              ],
            ),
          ),
        )
      ),
    );
  }
}