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problems wrapping Direct Input

Started by soddy Oct 28, 2005 at 5:20 PM 1 replies 650+ views

Original Post

Oct 28, 2005 at 5:20 PM

I'm trying to wrap direct input in one InputManager class but am having problems setting up callback functions. I want the enumDevicesCallBack and the enumObjectsCallBack to be member functions in the InputManager class but i keep getting compile errors.


hr = m_lpDirectInputInterface->EnumDevices( DI8DEVCLASS_GAMECTRL,							    enumControllersCB,
					    NULL, 
					    DIEDFL_ATTACHEDONLY );

The error i get is, "error C2664: 'IDirectInput8A::EnumDevices' : cannot convert parameter 2 from 'BOOL (const DIDEVICEINSTANCE *,void *)' to 'LPDIENUMDEVICESCALLBACKA' None of the functions with this name in scope match the target type" I have declared the function in the header as,


	BOOL CALLBACK enumControllersCB(const DIDEVICEINSTANCE* pdidInstance, VOID* pContext);

I've tried changing paramater 2 to cInputManager::enumControllersCB, but that doesnt help, same error message. also, doing this C style (ie declaring the function outside of the class as a standalone function) works fine, - why? Maybe this is a C/C++ question rather than DX, sorry if i misplaced it. [Edited by - Coder on October 28, 2005 11:37:11 PM]

jollyjeffers

Oct 28, 2005 at 5:44 PM

Quote:
doing this C style (ie declaring the function outside of the class as a standalone function) works fine, - why?

It's quite possible you've stumbled across a fundamental problem here [smile] At which point it is a C vs C++ problem.

Callbacks for regular "C style" functions defined outside a class are different to those defined "C++ style" inside a class. I forget all of the precise rules, but for the most part a function call into a C++ class requires a reference to "this" - the instance of the class that the function is being invoked against.

You might want to do some research into the topic of "functors".

hth
Jack

soddy

Oct 28, 2005 at 6:11 PM

Quote:
Original post by jollyjeffers
Callbacks for regular "C style" functions defined outside a class are different to those defined "C++ style" inside a class.
Jack

yup thats where the problem was, had to declare it as static within the class definition in header file.

cheers

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