# hw-app-btc: onDeviceStreaming Introduce a new callback to be notified on progress events of APDUs streaming, typically for each input of a transaction. onDeviceStreaming, if provided, will be called with an object `{ index, total, progress }`. Progress will varies from 0.0 to 1.0 (included). index will vary from 0 to total (included). onDeviceStreaming is not called at all if there is not more than X inputs. (today X = 3). In other words, it's only called when there is a significant waiting time to expect. A typically integration you can do is: - initially display a spinner/loading state to the user - hook to onDeviceStreaming to display user some progress `(e.progress*100).toFixed(0)+"%"` - hook to onDeviceSignatureRequested to know when you need to ask user to confirm on device - hook to onDeviceSignatureGranted to know when user have confirmed on the device (and resume to a spinner)