<?php
  require 'vendor/autoload.php';
  use PhpOfficePhpSpreadsheetIOFactory;
  use PhpOfficePhpSpreadsheetWorksheetPageSetup;
  use PhpOfficePhpSpreadsheetReaderXlsx;
  use PhpOfficePhpSpreadsheetWriterPdfMpdf;

  $reader = new PhpOfficePhpSpreadsheetReaderXlsx();
  $reader->setReadDataOnly(true);
  $spreadsheet = $reader->load("excel.xlsx");


  // when I use this MPDF class, I'm getting an error Class MpdfMpdf not found

  $writer = new PhpOfficePhpSpreadsheetWriterPdfMpdf($spreadsheet);
  $writer->save("excel.pdf");