PDF Thumbnailing in MODX - Proof of Concept

pdftojpeg.snippet.php

<?php
/**
 * Warning: this code is for demonstration purposes only
 */
if (!preg_match("/\.pdf$/", $input)) {
  return "PDF file not specified.";
}
$options = explode('&', $modx->getOption('options', $scriptProperties, null));

if(empty($options)){
 $ptOptions = array('w'=>400,'h'=>400,'f'=>'jpeg'); 
}else{
 $ptOptions = array();
 foreach($options as $opt){
   $o = explode('=',$opt);
   $ptOptions[$o[0]] = $o[1];
 }
 $ptOptions['w'] = (empty($ptOptions['w'])) ? 400 : $ptOptions['w'] + 0;
 $ptOptions['h'] = (empty($ptOptions['h'])) ? 400 : $ptOptions['h'] + 0;
 $ptOptions['f'] = (empty($ptOptions['f'])) ? 'jpeg' : $ptOptions['f'];
}
$format = ($ptOptions['f'] == 'jpeg') ? 'jpg' : $ptOptions['f'];
$targetFolder = $modx->getOption('target', $scriptProperties, '/assets/pdfcache');
$fullTargetFolderPath = str_replace('//','/',MODX_BASE_PATH . $targetFolder);
if(is_dir($fullTargetFolderPath) || mkdir($fullTargetFolderPath)){
    $cacheKey = hash('crc32',json_encode($ptOptions));                  
    $jpegFilename = basename($input, '.pdf') . '.' . $format;
    if(file_exists($fullTargetFolderPath . '/' . $cacheKey.$jpegFilename)){
     return  $targetFolder . '/' . $cacheKey.$jpegFilename;
    }
                        
    // instantiate Imagick 
    $im = new Imagick();
    
    $im->setResolution(300,300);
    $im->readimage(MODX_BASE_PATH . $input . '[0]'); 
    $im->setImageFormat($ptOptions['f']);    
    $im->resizeImage($ptOptions['w'],$ptOptions['h'],Imagick::FILTER_LANCZOS,1);
    $im->writeImage($fullTargetFolderPath . '/' . $cacheKey.$jpegFilename); 
    $im->clear(); 
    $im->destroy();
    return $targetFolder . '/' . $cacheKey.$jpegFilename;
}else{
    return 'Couldn\'t load directory.';
}

template.tpl

<p>This shows the usage of a simple snippet to create a jpeg image from a PDF file.</p>

[[pdftojpeg? &input=`assets/pdfs/4826092553.pdf` &options=`h=200&w=400`]]
or as an output modifier
[[*pdftv:pdftojpeg=`h=200&w=400`]]