Problem getting callback events from C code when using P/Invoke

**microcool1024** · Apr 26 '10, 07:45 PM

I am having a problem getting a C callback to correctly activate in a C# program after using a dllimport.

Here is the declaration of the C code in the C header:

Code:

typedef BOOL (CALLBACK *HII_PaymentAcceptedProc)(BYTE bSrcNode, BYTE bNumber, BYTE bType, WORD wValue);

HIIFAPI UINT WINAPI HII_PaymentAccepted(BYTE bDestNode, BYTE bNumber, BYTE bType, WORD wValue);

Then in the demo C program I have it is called like this:

Code:

HII_InstallPaymentAcceptedProc(PaymentAcceptedProc);


static BOOL CALLBACK PaymentAcceptedProc(BYTE bSrcNode, BYTE bNumber, BYTE bType, WORD wValue)
{
	LPTSTR lpszType;
	UNREFERENCED_PARAMETER(bSrcNode);

	// Payment accepted event received
	switch(bType)
	{
		case 0:		lpszType = TEXT("Coin");		break;
		case 1:		lpszType = TEXT("Value Token"); break;
		case 2:		lpszType = TEXT("Vend Token");	break;
		case 3:		lpszType = TEXT("Known Slug");	break;
		case 4:		lpszType = TEXT("Note");		break;
		default:	lpszType = TEXT("Unknown");		break;
	}

	FormatEvent(hwndMain, TEXT("Payment Accepted, number %u, type %s, value %u\r\n"),
		bNumber, lpszType, wValue);

	return TRUE;
}

I then tried to translate this into C# like this:

Code:

public delegate bool HII_PaymentAcceptedProc(Byte bSrcNode, Byte bNumber, Byte bType, UInt16 wValue);
[DllImport("HiiF.dll")]
public static extern UInt32 HII_InstallPaymentAccepted(HII_PaymentAcceptedProc pfnProc);

Then call it like this:

Code:

public bool PaymentAcceptedProc(byte bSrcNode, byte bNumber, byte bType, UInt16 wValue)
{
            switch(bType)
	{
		case 0:		break;
		case 1:		break;
		case 2:		break;
		case 3:		break;
		case 4:		break;
		default:	break;
	}
return true;
        }

HII_Wrapper.HII_PaymentAcceptedProc PaymentAcceptedProcDelegate = new HII_Wrapper.HII_PaymentAcceptedProc(this.PaymentAcceptedProc);

HII_Wrapper.HII_InstallPaymentAcceptedProc(PaymentAcceptedProcDelegate);

However it never his the PaymentAccepted Proc function and I don't understand why. Are there any thoughts? Am I handling the delegates incorrectly?