Progress support please

[ahmetveysels]

we have to see the progress at file upload time. can you support

[hellohejinyu]

int total = file.lengthSync();
Stream<List<int>> fs = file.openRead();
int byteLength = 0;
Stream<List<int>> stream = fs.transform(
  StreamTransformer.fromHandlers(
    handleData: (data, sink) {
      byteLength += data.length;
      print('uploading: ${byteLength / total * 100}%');
      sink.add(data);
    },
    handleError: (error, stackTrace, sink) {
      sink.close();
    },
    handleDone: (sink) {
      sink.close();
    },
  ),
);

You can handle the stream like this in the code above.

[jonasfj]

I think wrapping the stream is a good solution.

I don't think we need a solution for progress reporting in this package.

If someone wants to build a generic solution for making progress bars for streams that sounds like a good idea, but I don't think it belongs in this package. You can just have such a thing return a wrapped stream that you then pass to package:gcloud when uploading.