cache static method
Implementation
static Future<void> cache(String assetKey) async {
if (_cache.containsKey(assetKey) || _caching.contains(assetKey)) {
// This asset is already cached or is being cached.
return;
}
_caching.add(assetKey);
final program = await ui.FragmentProgram.fromAsset(assetKey);
_cache[assetKey] = program;
_caching.remove(assetKey);
}