expo-asset/src/Asset.fx.ts

An Expo universal module to download assets and pass them into other APIs

import type { default as AssetSourceResolver } from 'react-native/Libraries/Image/AssetSourceResolver';

import { Asset, ANDROID_EMBEDDED_URL_BASE_RESOURCE } from './Asset';
import { IS_ENV_WITH_LOCAL_ASSETS } from './PlatformUtils';
import resolveAssetSource, { setCustomSourceTransformer } from './resolveAssetSource';

// Override React Native's asset resolution for `Image` components in contexts where it matters
if (IS_ENV_WITH_LOCAL_ASSETS) {
  const setTransformer =
    resolveAssetSource.setCustomSourceTransformer || setCustomSourceTransformer;
  setTransformer((resolver) => {
    try {
      // Bundler is using the hashAssetFiles plugin if and only if the fileHashes property exists
      if ('fileHashes' in resolver.asset && resolver.asset.fileHashes) {
        const asset = Asset.fromMetadata(resolver.asset);
        if (asset.uri.startsWith(ANDROID_EMBEDDED_URL_BASE_RESOURCE)) {
          // TODO(@kitten): See https://github.com/expo/expo/commit/ec940b57a87d99ab4f1d06d87126e662c3f04f04#r155340943
          // It's unclear whether this is sound since this may be our own AssetSourceResolver, which doesn't have this method
          // Please compare `AssetSourceResolver` type from `react-native/Libraries/Image/AssetSourceResolver` against `./AssetSourceResolver`
          return (
            resolver as unknown as AssetSourceResolver
          ).resourceIdentifierWithoutScale() as any;
        }
        return resolver.fromSource(asset.downloaded ? asset.localUri! : asset.uri);
      } else {
        return resolver.defaultAsset();
      }
    } catch {
      return resolver.defaultAsset();
    }
  });
}