selective_focus_starter.dart

import 'dart:async';
import 'dart:ui' as ui;
import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Selective Focus',
      theme: ThemeData.dark(
        useMaterial3: true,
      ),
      home: const SelectiveFocus(),
    );
  }
}


class SelectiveFocus extends StatefulWidget {
  const SelectiveFocus({super.key});

  @override
  State<SelectiveFocus> createState() => _SelectiveFocusState();
}

class _SelectiveFocusState extends State<SelectiveFocus> {
  @override
  Widget build(BuildContext context) {
    return  SelectiveFocusImage();
  }
}

class SelectiveFocusImage extends StatefulWidget {
  const SelectiveFocusImage({super.key});

  @override
  State<SelectiveFocusImage> createState() => _SelectiveFocusImageState();
}

class _SelectiveFocusImageState extends State<SelectiveFocusImage> {
  ui.Image? _image;
  static const imageUrl = 'https://i.imgur.com/PVxynOu.png';

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

  Future<void> _loadImage() async {
    try {
      final completer = Completer<ui.Image>();
      final imageStream =
          const NetworkImage(imageUrl).resolve(ImageConfiguration.empty);

      imageStream.addListener(ImageStreamListener(
        (info, _) => completer.complete(info.image),
        onError: (error, _) => completer.completeError(error),
      ));

      _image = await completer.future;
      setState(() {});
    } catch (e) {
      debugPrint('Error loading image: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Selective Focus Image')),
      body: Center(
        child: Container(
          child: _image == null
              ? const CircularProgressIndicator()
              : CustomPaint(
                  size: Size(
                    _image!.width.toDouble(),
                    _image!.height.toDouble(),
                  ),
                  painter: InteractiveImagePainter(
                    image: _image!,
                  ),
                ),
        ),
      ),
    );
  }
}

class InteractiveImagePainter extends CustomPainter {
  final ui.Image image;

  const InteractiveImagePainter({required this.image});

  @override
  void paint(Canvas canvas, Size size) {
    canvas.drawImage(image, Offset.zero, Paint());
  }

  @override
  bool shouldRepaint(InteractiveImagePainter oldDelegate) =>
      image != oldDelegate.image;
}