Kernel-Mode Force Feedback Callbacks
This section contains reference information for the kernel-mode force feedback callbacks used by DirectInput. The COM methods are documented in the IDirectInputEffectDriver section of the DirectInput Reference. The equivalent VJoyD minidriver callbacks take the same parameters and return the same codes. Any exceptions to this are noted. These force feedback callbacks are divided into the following categories:
The return codes listed for the preceding callbacks do not represent the complete set of those possible. Some errors, such as an out-of-memory condition, may result in the DIERR_OUTOFMEMORY error code for any of the methods.
DirectInput has already done parameter checking where possible, so a driver should only attempt further validation where its requirements are nonstandard.
All magnitude and gain values used by DirectInput are uniform and linear across the range. Any nonlinearity in the physical device must be handled by the device driver so that the application interfaces with the device as if it were a linear device.