writeBytes method

@override Future writeBytes(List<int> data, { int chunkSize = defaultChunkSize, int chunkDelayMs = defaultChunkDelayMs, })

writeBytes writes raw data to the network socket in chunks.

Data is sent in chunkSize-byte pieces with a small delay and flush between each chunk. This prevents the printer's internal buffer from overflowing, which can cause:

• Incomplete prints / missing lines
• Printer treating data as multiple "pages" (A4-height output)
• Garbled output from buffer wrap-around

chunkSize — max bytes per write (default: 4096). chunkDelayMs — delay in ms between chunks (default: 5).

Implementation

@override
Future writeBytes(
  List<int> data, {
  int chunkSize = defaultChunkSize,
  int chunkDelayMs = defaultChunkDelayMs,
}) async {
  if (socket == null) {
    return Future.error(
        'Socket is not connected. Call connect() before writeBytes().');
  }

  try {
    final bytes = Uint8List.fromList(data);
    final totalLength = bytes.length;

    if (totalLength <= chunkSize) {
      // Small payload — send in one go.
      socket!.add(bytes);
      await socket!.flush();
    } else {
      // Large payload — send in chunks with flush + delay.
      int offset = 0;
      while (offset < totalLength) {
        final end =
            (offset + chunkSize > totalLength) ? totalLength : offset + chunkSize;
        socket!.add(bytes.sublist(offset, end));
        await socket!.flush();
        offset = end;

        // Small delay to let the printer process the chunk.
        if (offset < totalLength && chunkDelayMs > 0) {
          await Future.delayed(Duration(milliseconds: chunkDelayMs));
        }
      }
    }
  } catch (e) {
    return Future.error('Failed to write bytes: $e');
  }
}