public void FilterSelected(IFeatureSet sf)
{
int numShapes = sf.Table.NumRows;
_filterMap = new int[sf.NumSelected];
_filterMask = new bool[numShapes];
int count = 0;
for (int i = 0; i < numShapes; i++)
{
int realIndex = _sortingMap[i];
bool selected = sf.FeatureSelected(realIndex);
if (selected)
{
_filterMap[count] = realIndex;
_filterMask[realIndex] = true;
count++;
}
}
_filtered = true;
}