Thread: 2D SafeArrays- input data

I have a 2d safearray obtained from a variant, that needs to be populated with long values
I access the data:

Code:

hr = SafeArrayAccessData(pData, (void HUGEP* FAR*)&pDbl);

Here I need to input the data at it's correct position, but I cannot get this to work properly. The function

Code:

 pDbl[i*j] = val

runs but I get random results (the values I get in the output resemble very loosely what is expected).

And I unaccess the data:

Code:

hr = SafeArrayUnaccessData(pData);

Please help, my thesis in fact hinges on this working!

Will

Ok, here's some more. I get a blank variant array from a pixelblock object (ArcGIS API) and want to populate it using values from another pixelblock.

Code:

VARIANT vOutPixelArray;
ipOutputBlock3->put_PixelType(0, outPixelType);

// Get the SafeArray associated with the first band of output
ipOutputBlock3->get_PixelData(0, &vOutPixelArray);
SAFEARRAY *pData = (vOutPixelArray.parray); 

VARIANT v, vOut, vInNodatavalue, vOutNodatavalue;
long HUGEP *pDbl;

// QI RasterProps for output for NoData handling
IRasterPropsPtr ipOutputRasProps; 
ipOutputRasProps = ipOutBand;

    
//Loop through the SafeArray and calculate each pixel value according to the neighborhood-notation
long A, i, j;
long ij[2];
double getvalM;
double dVal;
ipInRasProps->get_NoDataValue(&vInNodatavalue);
ipOutputRasProps->get_NoDataValue(&vOutNodatavalue);

	//parses nodata variant
double dInNodatavalue = VDouble(vInNodatavalue, iPT);
hr = SafeArrayAccessData(pData, (void HUGEP* FAR*)&pDbl);

for (i=0; i<(lHeight - 1); i++)
{
ij[0]=i;
      for (j=0; j<(lWidth - 1); j++)
		  {
		  ij[1]=j;
      ipInputBlock3->GetVal(0, i, j, &v);
				
		  //extracts value from variant, discriminating between types
	   	dVal = VDouble(v, iPT);
		
      if (dVal == dInNodatavalue)
			{
			hr = SafeArrayPutElement(vOutPixelArray.parray, ij, &vOutNodatavalue);
				//pDbl[i*j] = dVal;
			}
			else
			if ((j + 1) < (lWidth))
					{
					//getvalS = ipInputBlock->GetVal(0, i, j, &v);
					dVal = dVal + 10;
					//vOut.vt = VT_I4
					vOut.vt = VT_I4;
					vOut.lVal = dVal;
					//getvalM = vOut.lVal;
					long lVal = dVal;
					pDbl[i*j] = lVal;
					
				//	hr = SafeArrayPutElement(vOutPixelArray.parray, ij, &vOut);

						
			   }               
		  }
	}

	
	hr = SafeArrayUnaccessData(pData);

I finally found the answer. For some reason I have to get a pointer to a pointer of a safearray, then use indirection to get a pointer?!

Code:

long *pMod
SAFEARRAY *pData = *(vOutPixelArray.pparray); 


hr = SafeArrayLock(pData);

//iterate through image(code removed)

		hr = SafeArrayPtrOfIndex(pData, ij, (void **)&pMod);
		if (FAILED(hr)) AfxMessageBox("nope");
					
		(*pMod) = dVal;//gives a pixel a value


hr = SafeArrayUnlock(pData);//unlocks the safearray

So simple! when you decode the MSDN "documentation".