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¿Cómo Extraigo Información de un SAFEARRAY en Microsoft Visual C++?

Software Primario: Measurement Studio>>Visual C++ Support
Versión de Software Primario: 7.0
Versión de Software Primario Corregido: N/A
Software Secundario: N/A

Problema:

Estoy utilizando un objeto CWAI de Measurement Studio y quiero extraer los datos desde el VARIANT que se pasa al evento AcquiredData. ¿Cómo hago esto?

Solución:
El siguiente ejemplo, escrito en Visual C++ muestra como extraer la información del VARIANT.

El texto también se encuentra en el archivo anexo SAFext.c.

void CMultiContAIinVCDlg::OnAcquiredDataCwai1(VARIANT FAR* ScaledData, 
             VARIANT FAR* BinaryCodes) 
{ 
 /* vOptional is used when we dont want to pass 
  anything to an optional argument */ 
 COleVariant vOptional((long)DISP_E_PARAMNOTFOUND,VT_ERROR);   
 
 /* We're going to use the CWArray.IndexArray function 
  from ComponentWorks to extract Channel 0 from BinaryCodes */ 
 VARIANT firstSignal;    // Channel 0 extracted from BinaryCodes 


 /* To use IndexArray, you must specify which part of the 2D array 
  to extract from BinaryCodes (or ScaledData). You do this by 
  creating a 1D SafeArray of two elements- the first is the first 
  dimension element to extract, the second is the second dimension 
  element to extract.  Specifying NULL causes an entire  
  dimension (row or column in a 2D array) to be extracted */


 VARIANT Array;    // VARIANT to use as a parameter for IndexArray 
 SAFEARRAY* psa;   // SAFEARRAY to specify extraction range 
 SAFEARRAYBOUND rgsabound[1]; 
 VARIANT vNull; 
 long ix[1];  
 
 /* Create 'psa': a 1D, 2 element array for specifying which part 
  of BinaryCodes (or ScaledData) to extract: */ 
 rgsabound[0].lLbound = 0; 
 rgsabound[0].cElements = 2; 
 psa = SafeArrayCreate(VT_VARIANT, 1, rgsabound); 


 // Specify Extraction: 
 // first dimension = channel 0 
 ix[0] = 0; 
 SafeArrayPutElement(psa, ix, COleVariant((long)0)); 


 // second dimension = VT_NULL (extract all scans of channel 0)
 x[0] = 1; 
 vNull.vt = VT_NULL; 
 SafeArrayPutElement(psa, ix, &vNull);  
 
 // Create VARIANT to contain psa: 
 // VARIANT type is a SAFEARRAY of VARIANTS 
 Array.vt = VT_ARRAY | VT_VARIANT;          
 
 // Use psa for the VARIANT's SAFEARRAY 
 Array.parray = psa;  
 
 // Call IndexArray to extract the information: 
 firstSignal = m_CWArray.IndexArray(*BinaryCodes,Array);  
 
 /* Extract elements from SAFEARRAY into an array of short integers:  
  Make sure 'firstSignal' is a 1D array of short integers 
  (for BinaryCodes) or // a 1D array of floats (for ScaledData): */ 



 if(firstSignal.parray->cDims == 1 && firstSignal.vt == (VT_ARRAY | VT_I2))    


  {   

  	// Buffer to store extracted values in
  	short *temparray = (short *) 0;  
 	 // keeps current position buffer being copied
  	short *iptr;        
  	int i;      


  	// Find size of firstSignal:  
  	int numElements = firstSignal.parray->rgsabound[0].cElements
    	  		 - firstSignal.parray->rgsabound[0].lLbound;    
  	
 	 // initialize array:  
  	temparray = new short[numElements];    
  
 	 // Get pointer to buffer to copy:  
 	 SafeArrayAccessData(firstSignal.parray, (void **) &iptr);    
  
 	 // Copy Buffer:  
 	 for(i = 0; iptr &&  i < numElements; i++)   
  	 temparray[i] = *(iptr+i);    
  
  	// Release pointer to buffer  
 	 SafeArrayUnaccessData(firstSignal.parray);   
  
 	 // When finished, release memory used by temparray.  
 	 delete temparray; 
   }
}