loadPreview method
Implementation
Future<void> loadPreview({VoidCallback? onChanged}) async {
if (thumbnail != null) {
return;
}
if (_previewTask != null) {
return _previewTask!;
}
_previewTask = _loadThumbnail().whenComplete(() {
onChanged?.call();
_previewTask = null;
});
return _previewTask!;
}