precache_image_custom.dart

import 'dart:async';
import 'dart:ui';
import 'package:flutter/widgets.dart';

// Usage:
Future<void> main() async {
  await precacheImageCustom(SplashPage.image);
  await precacheImageCustom(LoginPage.backgroundImage);

  runApp(App());
}

Future<void> precacheImageCustom(
  ImageProvider provider, {
  Size size,
  ImageErrorListener onError,
}) {
  WidgetsFlutterBinding.ensureInitialized();

  final ImageConfiguration config = ImageConfiguration(
    devicePixelRatio: MediaQueryData.fromWindow(window).devicePixelRatio,
  );
  final Completer<void> completer = Completer<void>();
  final ImageStream stream = provider.resolve(config);
  void listener(ImageInfo image, bool sync) {
    completer.complete();
    stream.removeListener(listener);
  }

  void errorListener(dynamic exception, StackTrace stackTrace) {
    completer.complete();
    stream.removeListener(listener);
    if (onError != null) {
      onError(exception, stackTrace);
    } else {
      FlutterError.reportError(FlutterErrorDetails(
        context: 'image failed to precache',
        library: 'image resource service',
        exception: exception,
        stack: stackTrace,
        silent: true,
      ));
    }
  }

  stream.addListener(listener, onError: errorListener);
  return completer.future;
}