The JDD_GETPOS message requests device coordinate and button information. Your driver fills in the JOYINFO structure and a pointer to it is passed in the lParam1 parameter. For a complete description of each JOYINFO field, see “Joystick Device Driver Data Structure Reference,” later in this chapter.
The coordinate values should be within the range your driver established when responding to the JDD_GETDEVCAPS message. When calculating the coordinate values, use the base and delta-calibration values passed to your 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.