Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Pdf/Dompdf.php
public function save($pFilename)
    {
        $fileHandle = parent::prepareForSave($pFilename);

        //  Default PDF paper size
        $paperSize = 'LETTER'; //    Letter    (8.5 in. by 11 in.)

        //  Check for paper size and page orientation
        if ($this->getSheetIndex() === null) {
            $orientation = ($this->spreadsheet->getSheet(0)->getPageSetup()->getOrientation()
                == PageSetup::ORIENTATION_LANDSCAPE) ? 'L' : 'P';
            $printPaperSize = $this->spreadsheet->getSheet(0)->getPageSetup()->getPaperSize();
        } else {
            $orientation = ($this->spreadsheet->getSheet($this->getSheetIndex())->getPageSetup()->getOrientation()
                == PageSetup::ORIENTATION_LANDSCAPE) ? 'L' : 'P';
            $printPaperSize = $this->spreadsheet->getSheet($this->getSheetIndex())->getPageSetup()->getPaperSize();
        }

        $orientation = ($orientation == 'L') ? 'landscape' : 'portrait';

        //  Override Page Orientation
        if ($this->getOrientation() !== null) {
            $orientation = ($this->getOrientation() == PageSetup::ORIENTATION_DEFAULT)
                ? PageSetup::ORIENTATION_PORTRAIT
                : $this->getOrientation();
        }
        //  Override Paper Size
        if ($this->getPaperSize() !== null) {
            $printPaperSize = $this->getPaperSize();
        }

        if (isset(self::$paperSizes[$printPaperSize])) {
            $paperSize = self::$paperSizes[$printPaperSize];
        }

        //  Create PDF
        $pdf = $this->createExternalWriterInstance();
        $pdf->setPaper(strtolower($paperSize), $orientation);

        $pdf->loadHtml(
            $this->generateHTMLHeader(false) .
            $this->generateSheetData() .
            $this->generateHTMLFooter()
        );
        $pdf->render();

        //  Write to file
        fwrite($fileHandle, $pdf->output());

        parent::restoreStateAfterSave($fileHandle);
    }
public function save($pFilename)
    {
        $fileHandle = parent::prepareForSave($pFilename);

        //  Default PDF paper size
        $paperSize = 'LETTER'; //    Letter    (8.5 in. by 11 in.)

        //  Check for paper size and page orientation
        if ($this->getSheetIndex() === null) {
            $orientation = ($this->spreadsheet->getSheet(0)->getPageSetup()->getOrientation()
                == PageSetup::ORIENTATION_LANDSCAPE) ? 'L' : 'P';
            $printPaperSize = $this->spreadsheet->getSheet(0)->getPageSetup()->getPaperSize();
        } else {
            $orientation = ($this->spreadsheet->getSheet($this->getSheetIndex())->getPageSetup()->getOrientation()
                == PageSetup::ORIENTATION_LANDSCAPE) ? 'L' : 'P';
            $printPaperSize = $this->spreadsheet->getSheet($this->getSheetIndex())->getPageSetup()->getPaperSize();
        }

        $orientation = ($orientation == 'L') ? 'landscape' : 'portrait';

        //  Override Page Orientation
        if ($this->getOrientation() !== null) {
            $orientation = ($this->getOrientation() == PageSetup::ORIENTATION_DEFAULT)
                ? PageSetup::ORIENTATION_PORTRAIT
                : $this->getOrientation();
        }
        //  Override Paper Size
        if ($this->getPaperSize() !== null) {
            $printPaperSize = $this->getPaperSize();
        }

        if (isset(self::$paperSizes[$printPaperSize])) {
            $paperSize = self::$paperSizes[$printPaperSize];
        }

        //  Create PDF
        $pdf = $this->createExternalWriterInstance();
        $pdf->setPaper(strtolower($paperSize), $orientation);

        $pdf->loadHtml(
            $this->generateHTMLHeader(false) .
            $this->generateSheetData() .
            $this->generateHTMLFooter()
        );
        $pdf->render();

        //  Write to file
        fwrite($fileHandle, $pdf->output());

        parent::restoreStateAfterSave($fileHandle);
    }
Save Spreadsheet to file.

@param string $pFilename Name of the file to save as

@throws \PhpOffice\PhpSpreadsheet\Writer\Exception