Such questions are answered with a call to the IDirectInputDevice8::GetCapabilities method, which returns the data in a DIDEVCAPS structure. As with other such structures in Microsoft® DirectX®, you must initialize the dwSize member before passing this structure to the method.

Note  To optimize speed or memory usage, you can use the smaller DIDEVCAPS_DX3 structure instead. For structure details, see Dinput.h.

The following code example checks whether the mouse is attached and whether it has a third axis (presumably a wheel). Assume that lpdiMouse is a valid Microsoft® DirectInput® device.

DIDEVCAPS  DIMouseCaps; 
HRESULT    hr; 
BOOLEAN    WheelAvailable; 
 
DIMouseCaps.dwSize = sizeof(DIDEVCAPS); 
hr = lpdiMouse->GetCapabilities(&DIMouseCaps); 
WheelAvailable = ((DIMouseCaps.dwFlags & DIDC_ATTACHED) 
        && (DIMouseCaps.dwAxes > 2)); 

Another way to check for a button or axis is to call IDirectInputDevice8::GetObjectInfo for that object. If the call returns DIERR_OBJECTNOTFOUND, the object is not present. The following code determines whether there is a z-axis, even if it is not the third axis:

DIDEVICEOBJECTINSTANCE  didoi; 
 
didoi.dwSize = sizeof(DIDEVICEOBJECTINSTANCE); 
hr = lpdiMouse->GetObjectInfo(&didoi, DIMOFS_Z, DIPH_BYOFFSET); 
WheelAvailable = SUCCEEDED(hr);