PHP Downsizing or Converting PDF for Live Preview

Question

Problem

Currently working on creating a live PDF generation preview in Laravel PHP using using PDFI + TCPDF so that a user can import a base PDF and embed text on top of it
PDF generation is working fine for all sizes, but large PDFs (e.g. A1 size) generates a 10+ MB file that is too large to serve back to the front end for preview
Looking for the quickest and best method to either optimise and reduce the PDF file size, or resize the actual PDF dimension to serve a minified version for preview only

TLDR
Looking for suggestions (other than those I've tried below), or improvements on what I've tried to create a PDF preview file either through resizing or converting to image file of original large PDF.

What I've Tried So Far

Imagick PDF to Image Conversion - Good output size (31mb > 700kb) but slow (1secs > 10secs)
Converting PDF to image using Imagick before creating a minified PDF using the image was my original idea however I found that Imagick was really slow at reading the PDF blob image (takes about 9 seconds compared to sub 1 second for the PDF generation itself). Code is as follows

    // $output === the PDF generated
    $downscaleSizeFactor = $this->jsonFile->canvas['downscale_size_factor'] ?? 1;
    $previewWidth = $this->size['width'] / $downscaleSizeFactor;
    $previewHeight = $this->size['height'] / $downscaleSizeFactor;

    $im = new Imagick;
    $im->readImageBlob($output); // SLOW HERE!!!
    $numPages = $im->getNumberImages();

    $pdfPreview = new TCPDF($this->size["orientation"], 'mm', [$previewWidth,  $previewHeight], true, 'UTF-8', false);
    $pdfPreview->setPrintHeader(false);
    $pdfPreview->setPrintFooter(false);
    $pdfPreview->SetAutoPageBreak(false, 0);

    for($i=0;$i<$numPages;$i++) {
      $im->setIteratorIndex($i);
      $selectedIm = $im->getImage();
      $selectedIm->resizeImage($previewWidth,  $previewHeight, imagick::FILTER_LANCZOS, 1, true);
      $selectedIm->setImageBackgroundColor('white');
      $selectedIm->setImageAlphaChannel(Imagick::ALPHACHANNEL_REMOVE);
      $selectedIm->mergeImageLayers(Imagick::LAYERMETHOD_FLATTEN);
      $selectedIm->setImageFormat('png');
      $selectedIm->setImageCompressionQuality(100);
      $imageString = $selectedIm->getImageBlob();

      // add a page
      $pdfPreview->AddPage();
      // set JPEG quality
      $pdfPreview->setJPEGQuality(100);
      $pdfPreview->Image('@'.$imageString, 0, 0, $previewWidth,  $previewHeight);
    }

    $im->clear();
    $im->destroy();

    return $pdfPreview->output('', 'S');

Rerun FPDI + TCPDF to generated Minified Version - Bad output size (31mb > 31mb) but extremely fast (1secs > 1.5secs)
Saving the generated PDF to a temporary folder, then using the generated PDF to generate a minified version for preview only. This worked great in terms of speed, however it didn't change the file size at all. Reducing from [600 mm x 800 mm] to [10 mm x 10 mm] did not reduce the file size at all, which is weird. Maybe I missed something if anyone can see. Code as follows

    $reducedPdf = new FpdiTcpdfCustom();
    $tempPdfFile = storage_path('app/templates/pdf/temp/'.$name.'');
    $pageCount = $reducedPdf->setSourceFile($tempPdfFile);

    $pageNo = 1;
    for ($pageNo; $pageNo <= $pageCount; $pageNo++) {
      // Checks if the page is to be skipped

      // Import a page from the blank by setting the
      $pageId = $reducedPdf->importPage($pageNo);
      // Return the size of the imported page
      $size = $reducedPdf->getTemplateSize($pageId);

      // Remove default header/footer
      $reducedPdf->setPrintHeader(false);
      $reducedPdf->setPrintFooter(false);
      $reducedPdf->SetAutoPageBreak(false, 0);

      // Creates the PDF page
      $reducedPdf->AddPage($size['orientation'], [10,10]);
      $reducedPdf->useTemplate($pageId, 0, 0, 10, 10);
    }

    return $reducedPdf->output('', 'S');

Using Spatie\PdfToImage to generate Image File - Good output size (31mb > 218kb) but rubbish speed (1secs > 27secs just to convert and save image)
Similar to previous, looking to convert the PDF to an image file, before resizing and embedding the image into a PDF for preview. But it is extremely slow so I gave up on this method before even generating the PDF.

    $tempPdf = new \Spatie\PdfToImage\Pdf(storage_path('app/templates/pdf/temp/'.$name));
    $tempPdf->setCompressionQuality(10); 
    $tempPdf->saveImage(storage_path('app/templates/pdf/temp/'));

Suggestions?
Does anyone have suggestion on either improving my attempts, or another way of achieving what I need?

PHP Downsizing or Converting PDF for Live Preview

0 Answers0