insertN method
Implementation
void insertN(int index, int count) {
final moveStart = index * _cellSize;
final moveOffset = count * _cellSize;
final bufferEnd = _maxCols * _cellSize;
// move data forward
for (var i = bufferEnd - moveOffset - 1; i >= moveStart; i--) {
_cells[i + moveOffset] = _cells[i];
}
// set inserted cells to 0
for (var i = moveStart; i < moveStart + moveOffset; i++) {
_cells[i] = 0x00;
}
}