Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Pdf/Mpdf.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 (null === $this->getSheetIndex()) {
            $orientation = ($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();
        }
        $this->setOrientation($orientation);

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

        //  Override Paper Size
        if (null !== $this->getPaperSize()) {
            $printPaperSize = $this->getPaperSize();
        }

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

        //  Create PDF
        $config = ['tempDir' => $this->tempDir];
        $pdf = $this->createExternalWriterInstance($config);
        $ortmp = $orientation;
        $pdf->_setPageSize(strtoupper($paperSize), $ortmp);
        $pdf->DefOrientation = $orientation;
        $pdf->AddPage($orientation);

        //  Document info
        $pdf->SetTitle($this->spreadsheet->getProperties()->getTitle());
        $pdf->SetAuthor($this->spreadsheet->getProperties()->getCreator());
        $pdf->SetSubject($this->spreadsheet->getProperties()->getSubject());
        $pdf->SetKeywords($this->spreadsheet->getProperties()->getKeywords());
        $pdf->SetCreator($this->spreadsheet->getProperties()->getCreator());

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

        //  Write to file
        fwrite($fileHandle, $pdf->Output('', 'S'));

        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 (null === $this->getSheetIndex()) {
            $orientation = ($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();
        }
        $this->setOrientation($orientation);

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

        //  Override Paper Size
        if (null !== $this->getPaperSize()) {
            $printPaperSize = $this->getPaperSize();
        }

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

        //  Create PDF
        $config = ['tempDir' => $this->tempDir];
        $pdf = $this->createExternalWriterInstance($config);
        $ortmp = $orientation;
        $pdf->_setPageSize(strtoupper($paperSize), $ortmp);
        $pdf->DefOrientation = $orientation;
        $pdf->AddPage($orientation);

        //  Document info
        $pdf->SetTitle($this->spreadsheet->getProperties()->getTitle());
        $pdf->SetAuthor($this->spreadsheet->getProperties()->getCreator());
        $pdf->SetSubject($this->spreadsheet->getProperties()->getSubject());
        $pdf->SetKeywords($this->spreadsheet->getProperties()->getKeywords());
        $pdf->SetCreator($this->spreadsheet->getProperties()->getCreator());

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

        //  Write to file
        fwrite($fileHandle, $pdf->Output('', 'S'));

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

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

@throws \PhpOffice\PhpSpreadsheet\Writer\Exception
@throws PhpSpreadsheetException