load method
Converts a key into an PictureStreamCompleter, and begins fetching the picture.
Implementation
@override
PictureStreamCompleter load(PictureKey<String> key,
{PictureErrorListener? onError}) {
return OneFramePictureStreamCompleter(
_loadAsync(key, onError: onError),
informationCollector: () => <DiagnosticsNode>[
DiagnosticsProperty<String>('Path', file.path),
],
);
}