What is RIDI_PREPARSEDDATA in GetRawInputDeviceInfo?

Question

Windows API function GetRawInputDeviceInfo has a parameter uiCommand. One of the options is RIDI_PREPARSEDDATA. It says "pData points to the previously parsed data".

I don't get what previously parsed data they are referring to. Is it the data that was last sent with WM_INPUT? Or is it data that was returned by any of the functions? Or something else? Also in what format is that data?

Answer 1

Preparsed data is report descriptor data associated with a top-level collection. User-mode applications or kernel-mode drivers use preparsed data to extract information about specific HID controls without having to obtain and interpret a device's entire report descriptor.

MSDN Link