This message is sent to get device capability information.
LPARAM lParam1
Specifies a far pointer to a JOYCAPS data structure. The driver fills this structure with the capabilities of the device.
LPARAM lParam2
Specifies the size of the structure pointed to by lParam1.
Return MMSYSERR_NOERROR if successful. Otherwise, return JOYERR_PARMS.
Compare the structure size value passed to lParam2 with the size of the JOYCAPS structure with which your driver was compiled. If lParam2 is larger than the expected structure size, you should fill the remaining data with zeros.
If lParam2 is 0, return MMSYSERR_NOERROR without writing anything to the location specified by lParam1.