ILayerCell cell = natTable.getCellByPosition(colIndex, rowIndex);

ICellPainter cellPainter = natTable.getCellPainter(colIndex, rowIndex, cell, configRegistry);
int preferredColWidth = cellPainter.getPreferredWidth(cell, gc, configRegistry);

MaxCellBoundsHelper.getPreferedColumnWidths(IConfigRegistry configRegistry, GCFactory gcFactory, ILayer layer, int[]columnPositions) {

    /**
     * @return the index of the first visible row
     */
    private int getFirstVisibleRow() {
        int firstRowIndex = viewportLayer.getRowPositionByIndex(0) * -1;
        return firstRowIndex;
    }

    /**
     * @return the index of the last visible row
     */
    private int getLastVisibleRow() {
        int firstVisibleRow = getFirstVisibleRow();
        int lastVisibleRow = firstVisibleRow + viewportLayer.getRowCount() - 1;
        return lastVisibleRow;
    }