public function calculateColumnWidths()
    {
        // initialize $autoSizes array
        $autoSizes = [];
        foreach ($this->getColumnDimensions() as $colDimension) {
            if ($colDimension->getAutoSize()) {
                $autoSizes[$colDimension->getColumnIndex()] = -1;
            }
        }

        // There is only something to do if there are some auto-size columns
        if (!empty($autoSizes)) {
            // build list of cells references that participate in a merge
            $isMergeCell = [];
            foreach ($this->getMergeCells() as $cells) {
                foreach (Coordinate::extractAllCellReferencesInRange($cells) as $cellReference) {
                    $isMergeCell[$cellReference] = true;
                }
            }

            // loop through all cells in the worksheet
            foreach ($this->getCoordinates(false) as $coordinate) {
                $cell = $this->getCell($coordinate, false);
                if ($cell !== null && isset($autoSizes[$this->cellCollection->getCurrentColumn()])) {
                    //Determine if cell is in merge range
                    $isMerged = isset($isMergeCell[$this->cellCollection->getCurrentCoordinate()]);

                    //By default merged cells should be ignored
                    $isMergedButProceed = false;

                    //The only exception is if it's a merge range value cell of a 'vertical' randge (1 column wide)
                    if ($isMerged && $cell->isMergeRangeValueCell()) {
                        $range = $cell->getMergeRange();
                        $rangeBoundaries = Coordinate::rangeDimension($range);
                        if ($rangeBoundaries[0] == 1) {
                            $isMergedButProceed = true;
                        }
                    }

                    // Determine width if cell does not participate in a merge or does and is a value cell of 1-column wide range
                    if (!$isMerged || $isMergedButProceed) {
                        // Calculated value
                        // To formatted string
                        $cellValue = NumberFormat::toFormattedString(
                            $cell->getCalculatedValue(),
                            $this->getParent()->getCellXfByIndex($cell->getXfIndex())->getNumberFormat()->getFormatCode()
                        );

                        $autoSizes[$this->cellCollection->getCurrentColumn()] = max(
                            (float) $autoSizes[$this->cellCollection->getCurrentColumn()],
                            (float) Shared\Font::calculateColumnWidth(
                                $this->getParent()->getCellXfByIndex($cell->getXfIndex())->getFont(),
                                $cellValue,
                                $this->getParent()->getCellXfByIndex($cell->getXfIndex())->getAlignment()->getTextRotation(),
                                $this->getParent()->getDefaultStyle()->getFont()
                            )
                        );
                    }
                }
            }

            // adjust column widths
            foreach ($autoSizes as $columnIndex => $width) {
                if ($width == -1) {
                    $width = $this->getDefaultColumnDimension()->getWidth();
                }
                $this->getColumnDimension($columnIndex)->setWidth($width);
            }
        }

        return $this;
    }