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:

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

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

Code:

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pDbl[i*j] = val

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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:

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hr = SafeArrayUnaccessData(pData);

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

Will

Well, either you're accessing the wrong part of the array or the array wasn't allocated properly (which is most likely).

Post some more code. We can't make much out from what you have.

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:

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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);

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have you tried using as an index

iCurrentHeight*iTotalWidth + iCurrentWidth

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:

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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

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