2.2.4.6.5 DataObject::GetInternalDataBuffer

GetInternalDataBuffer

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 Header to Include

Description

Get internal Data buffer of Column or MatrixObject.

Syntax

LPVOID GetInternalDataBuffer( int * pnElementSize = NULL, uint * pnNumElements = NULL )

Parameters

pnElementSize: [output] if it is not NULL, get the size of data type of element.
pnNumElements: [output] if it is not NULL, get the number of element in the object.

Return

If the data type is mixed, return NULL, otherwise return internal data buffer.

Examples

EX1

void DataObject_GetInternalDataBuffer_Ex1()
{
	Worksheet wks = Project.ActiveLayer();
	if(wks)
	{
		Column col(wks, 0); // first column
		
		if( col )
		{			
			int nElementSize;
			uint nNum;
			LPVOID pData = col.GetInternalDataBuffer(&nElementSize, &nNum);				
			if(NULL == pData)
				out_str("return NULL if col is Text type or mixed type");
			else
			{
				if(0 != nNum)
				{
					double *pTemp = (double*)pData; // cast to double since cannot direclty access the value of void type pointer point to 
					*pTemp = 0.5; // change the value of first item 
					col.ReleaseBuffer(); // after call this, first row of first column will change to 0.5
				}
			}
		}
	}	
}

EX2

//This example show how to set a column to two-byte integers and get its 
//pointer to assign values to

void DataObject_GetInternalDataBuffer_Ex2(int nRows = 10000)
{
	Worksheet wks = Project.ActiveLayer();
	if(wks)
	{
		Column col(wks, 0); // first column
		if( col )
		{
			col.SetFormat(OKCOLTYPE_NUMERIC);
			col.SetInternalData(FSI_SHORT);
			col.SetUpperBound(nRows-1);//index of last row, 0 offset
			int nElementSize;
			uint nNum;
			LPVOID pData = col.GetInternalDataBuffer(&nElementSize, &nNum);
			printf("nElementSize = %d, Num Rows = %d\n", nElementSize, nNum);
			short* psBuff = (short*)pData;
			// OC loop is still slow, but you might pass this pointer to your DLL
			// for much faster manipulation, here we just show that the pointer works
			for(int ii = 0; ii < nRows; ii++, psBuff++)
			{
				*psBuff = (ii+1)*2;
			}
			col.ReleaseBuffer();
		}
	}	
}

EX3

//This example will double all the cell's value of the active matrixobject
void DataObject_GetInternalDataBuffer_Ex3()
{
	//assume there exists an active matrixsheet
	MatrixLayer mtx = Project.ActiveLayer();
	if ( !mtx )
	{
		printf("Can not get active matrixsheet");
		return;
	}
	MatrixObject mo = mtx.MatrixObjects(0); //get first matrix object
	int nEleSize;
	uint nSize;
	mo.SetFormat(OKCOLTYPE_NUMERIC);
	mo.SetInternalData(FSI_SHORT);
	LPVOID lpData = mo.GetInternalDataBuffer(&nEleSize, &nSize);
	short* psData = (short*)lpData;
	for ( int ii = 0; ii < nSize; ii++, psData++)
	{
		*psData = *psData * 2;
	}
	mo.ReleaseBuffer();
	return;
}

Remark

You need to call SetUpperBound in a column before you can access the data, unless the column already has upper bound set.

Header to Include

origin.h