macos.py 文件源码

def GetDeviceIntProperty(dev_ref, key):
  """Reads int property from the HID device."""
  cf_key = CFStr(key)
  type_ref = iokit.IOHIDDeviceGetProperty(dev_ref, cf_key)
  cf.CFRelease(cf_key)
  if not type_ref:
    return None

  if cf.CFGetTypeID(type_ref) != cf.CFNumberGetTypeID():
    raise errors.OsHidError('Expected number type, got {}'.format(
        cf.CFGetTypeID(type_ref)))

  out = ctypes.c_int32()
  ret = cf.CFNumberGetValue(type_ref, K_CF_NUMBER_SINT32_TYPE,
                            ctypes.byref(out))
  if not ret:
    return None

  return out.value