在joomla中创建上传pdf的缩略图

Question

我想创建PDF的缩略图。我无法创建缩略图。在原始PHP中它可以工作，但在Joomla它不起作用。请让我知道我做错了什么。

$uploadPath = JPATH_ADMINISTRATOR . '/components/com_ets_fast_track/assets/buildings/' . $filename;
$fileTemp = $file['tmp_name'];

if(!JFile::exists($uploadPath)){

    //name the thumbnail image the same as the pdf file
    $pdfWithPath = $uploadPath;

    $thumbDirectory = JPATH_ADMINISTRATOR . '/components/com_ets_fast_track/assets/buildings/';
    $thumb = basename($filename, ".pdf");

    //add the desired extension to the thumbnail                                        
    $thumb = $thumbDirectory.$thumb.".jpg";

    //execute imageMagick's 'convert', setting the color space to RGB and size to 200px wide
    exec("convert $pdfWithPath[0]  $thumb");

}