Asynchronous Operation In Main

Hi everyone,

I'm testing an optical fingerprint device which has an asynchronous operation with a flow like the following:

1) LoadFG() - This will initialize device, camera, etc

2) SetProp() - Set frame grabber properties like LED, capture modes, etc

3) StartCapture() - This functions returns immediately but it triggers asynchrounous operation capturing images at intervals "in the background" untill StopCapture() is called.

StartCapture() takes the following callback functions as parameters

1) OnImage

2) OnFinger

3) OnError

I just want to write a simple test in my main function. How do I handle the async operations so that my main doesn't terminate before I stop the async operation properly.

I'm using Visual Studio 2008.

Code:

#include "stdafx.h"
#include <iostream>
#include <Windows.h>
//This header defines all the data structures
#include "Devicevcdefs.h"
//The DLL header
#include "Devicevc.h"

#pragma comment(lib, "Device.lib")

using namespace std;

/////////////////////////Callback Functions //////////////////////////


// The Image Event
void OnImage( int nFGHandle, unsigned int nChannel, DRM_VC_BYTE* pImage, void* pClientData )
{
	cout<< "OnImage" << endl;

}
// The finger event
void OnFinger( int nFGHandle, unsigned int nChannelNo, int nType, DRM_VC_BYTE* pImage, void* pClientData )
{
	cout << "OnFinger" <<  endl;	

}
// The error event
void OnError( int nFGHandle, unsigned int nChannel, const char* szErrMsg, void* pClientData )
{
	 cout << "Error: " << szErrMsg <<  endl;

}
// The warning event
void OnWarning( int nFGHandle, unsigned int nChannel, const char* szWarningMsg, void* pClientData )
{
	 cout << "Warning: " << szWarningMsg <<  endl;
}

//////////////////////////End Callback Functions///////////////////////


int _tmain(int argc, _TCHAR* argv[])
{
	int nFGHandle;
	
	// Load the frame grabber from the dl which in turns initialize the device
	//FG_PLS1 is device type enum
	loadFGStatus = LoadFG(FG_PLS1, nFGHandle);
	
	
	if(loadFGStatus == DEVICE_NOERROR){
		//Output 0 which is OK
		cout << loadFGStatus << endl;
		//Output 1 which is OK
		cout << nFGHandle << endl;
		
		//Set The device LED to green
		SetFGProperty (nFGHandle, FG_GREEN_LED, 1);	
		
		//I'm stuck here!
		//The asynchrounous operation, this method returns immediately but 
		//triggers image capture intervals in the background
		//Will only stop after issuing StopCapture()
		StartCapture( nFGHandle, 1, PLAIN_FINGER , OnImage , OnFinger , OnError , OnWarning , NULL );
		
		//Next Steps here....

	}

	system("pause");

	return 0;
}

Pardon my noob question, I'm not a professional, just a lone business operator trying to get things done within budget and without going out of business. Any tips?

Thank you in advanced!

you need to add some waiting loop. Example of the loop could be found here Named Pipe Server Using Completion Routines (Windows)

if you do not have any event you want to wait (which will be signaled when processing is done)

you can wait for the current thread handle - this wait will exit only due to messages to be processed, you will need to use some boolean flag indicating that the loop should be broken

Thanks Vart, that is a good example.