The JDD_GETPOS message requests device coordinate and button information. A joystick driver fills in the JOYINFO structure and a pointer to it is passed in the lParam1 parameter.
The coordinate values should be within the range the driver established when responding to the JDD_GETDEVCAPS message. When calculating the coordinate values, use the base and delta-calibration values passed to the driver with the JDD_SETCALIBRATION message.
See "Sample Source Code," later in this chapter, for a detailed description of how the IBMJOY device driver handles the JDD_GETPOS message.