DomPDF Render with Progress Callback

dompdf-with-progress-callback.php

<?php

use Dompdf\Dompdf;


$totalFramesToRenderCount = 0;
$finishedFramesToRenderCount = 0;
$onProgress = function($percentage, $framesRendered, $framesTotal){
  //This is the callback that will be called every progress change
  var_dump($percentage, $framesRendered, $framesTotal);
};



//Instatiate DomPDF
$dompdf = new Dompdf();
$dompdf->setCallbacks([
    'begin_frame' => [
        "event" => "begin_frame",
        "f" => function ($frame) use (&$dompdf, &$totalFramesToRenderCount){
            //This callback will be executed once, on the first PDF frame render, this will count how many frames needs to be rendered.
            if ($totalFramesToRenderCount !== 0){
                return;
            }
          
            $reflection = new \ReflectionClass($dompdf);
            $property = $reflection->getProperty('tree');
            $property->setAccessible(true);
            $tree = $property->getValue($dompdf);

            foreach ($tree as $frame) {
                $totalFramesToRenderCount++;
            }
        }
    ],
    'end_frame' => [
        'event' => 'end_frame',
        'f' => function ($frame) use (&$finishedFramesToRenderCount, &$totalFramesToRenderCount, &$onProgress) {
            //On every frame rendering, this callback will be executed
            $finishedFramesToRenderCount++;

            if ($totalFramesToRenderCount === 0 || $finishedFramesToRenderCount > $totalFramesToRenderCount){
                return;
            }
            $onProgress($finishedFramesToRenderCount / $totalFramesToRenderCount * 100, $finishedFramesToRenderCount, $totalFramesToRenderCount);
        }
    ]
]);


$dompdf->loadHtml('<h1>Hello world</h1>');
$dompdf->setPaper('A4', 'portrait');
$dompdf->render();