Flutter precacheImage example

main.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({
    super.key,
    required this.title,
  });
  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  late NetworkImage _networkImage;

  @override
  void initState() {
    super.initState();
    _networkImage = const NetworkImage(
      'https://images.unsplash.com/photo-1653184849936-f64ad1081f96',
    );
  }

  @override
  void didChangeDependencies() {
    precacheImage(_networkImage, context);
    super.didChangeDependencies();
  }

  void _showImageDialog() {
    showDialog<void>(
      context: context,
      builder: (context) {
        return SimpleDialog(
          children: [
            Image(image: _networkImage),
          ],
        );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(_networkImage.url),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _showImageDialog,
        child: const Icon(Icons.add),
      ),
    );
  }
}