onProgress property

void Function(int bytesWritten, int? totalBytes)? onProgress

Optional progress callback for streaming writes.

Called periodically with the bytes written so far and the total when known — totalBytes is null while the total is unknown (streaming input has no length until it ends).

Progress is reported in the CALLER's byte space: an encrypted write reports plaintext bytes consumed, not ciphertext bytes landed, so a progress bar over the source size stays accurate.

Only meaningful for StorageBackend.writeStream. Ignored for StorageBackend.write (single buffer, no progress).

Implementation

final void Function(int bytesWritten, int? totalBytes)? onProgress;