jbaiter / hidapi-cffi Goto Github PK

send_feature_report and get_feature_report have report_id parameters whose type is documented to be int. send_feature_report defaults the parameter to 0x0, an int.

However, they both write the report ID to the first byte of a CFFI buffer, which fails on Python 3:

Suppose I have this code:

dev.send_feature_report(b"\x00", 0x20)

It fails:

Traceback (most recent call last):
  File "./test.py", line 23, in <module>
    dev.send_feature_report(b"\x00", 0x20)
  File "/home/rprichard/proj/logitech-g400-config/hidapi_cffi/hidapi.py", line 284, in send_feature_report
    buf[0] = report_id
TypeError: must assign a bytes of length 1, not int

To make it work, I must instead pass a 1-byte bytestring for the report ID:

dev.send_feature_report(b"\x00", b"\x20")

I'm using:

• the very latest hidapi-cffi code
• Xubuntu 16.04
• distribution-provided Python3 and python3-cffi packages

I also tried replacing python3-cffi with one installed by pip3, but it made no difference.

Aside: is it actually useful to default the report_id for send_feature_report to 0x0? I think it'd might make sense if the default behavior instead omitted the report ID from the buffer passed to hidapi.hid_send_feature_report, but that's not what happens.