stianlik

Hi,

First, a control question: Did you upload both images after you activated the plugin? If the answer is no, you can regenerate the thumbnails, or simply delete the PDF and upload it a second time with the plugin activated.

Can you check if the thumbnail image has been generated? It will be saved as a normal image and you can find it in the media manager with title “Winter_2014_Newsletter_V1-thumbnail”.

PDF thumbnails are connected to the PDF in the same way as featured images are to posts, with the meta key _thumbnail_id on the PDF attachment. Additionally every PDF thumbnail is marked with post meta PdfThumbnailsPlugin set to true.

I uploaded both of the files you linked to on a test installation and was able to retrieve thumbnails for both.

This may be caused by an outdated server setup. The __DIR__ constant is not supported for PHP versions older than 5.3. Can you check which version you are running?

I just releasted a new version that should be backward compatible with PHP 5.2. Please update to version 0.0.5 and let me know if it works. Thanks.

Yes, this will work if you have multiple PDF’s on the same page. PDF thumbnails are implemented as Post_Thumbnails for attachments and can be used in the same way.

I have never used ACF, so I’m not familiar with the API you’re using. However, I found some documentation for the ACF File field. To get the attachment ID, you need to set Return Value to Attachment ID instead of File URL. The preceding link has an example of how you can proceed, in short, use $attachment_id = get_field('case_study_pdf'); to get the $id after setting Return Value to Attachment ID in the field configuration screen.

Hi,

You can create a download link for the PDF with the following snippet:

<?php $id = get_the_ID(); ?>
<a href="<?php echo wp_get_attachment_url($id); ?>">
    <?php echo get_the_post_thumbnail($id); ?>
</a>

Replace $id with ID of the PDF attachment you are interested in linking to. The example assumes that you are in “The Loop”, viewing an attachment page.

The plugin should not cause any problems from ACF as far as i know. Thumbnails are saved as normal uploads in the media library.

The thumbnail is automatically attached to the PDF as a “featured image” when PDF is uploaded. No need to perform additional steps here.

If you are up to it, you will probably get a more helpful error message in the web server log. You can find the log file in the following places:

• Debian/Ubuntu: /var/log/apache2/error.log
• OSX: /var/log/apache2/error_log

Othewise, it may be helpful to enable debug-mode for WordPress by editing wp-config.php, see Editing wp-config.php for details.

Can you post the error message you are getting?

If you have PDF support in imagick, this plugin should be working. The reason that you need Ghostscript, is to enable PDF support for imagick.

Great! Thank you for posting the solution, and a great review.

Actually, get_the_post_thumbnail($id) calls wp_get_attachment_image_src($id) internally, so you should be able to make it work with the code below. In my earlier comment, $filethumb should have been $attachment_id, sorry for the blunder.

<?php $attachment_id = get_field('file'); ?>
<div class="thumb">
    <?php echo get_the_post_thumbnail($attachment_id, 'medium'); ?>
</div>

That would make your code slightly easier to read.

Good look with your imports, marking this as resolved ??

A subtle detail of the_post_thumbnail() is that it only works with current post in The Loop, you cannot pass an ID to that function. Your code should work if you replace the_post_thumbnail with echo get_the_post_thumbnail:

<?php echo get_the_post_thumbnail($filethumb); ?>

You are correct, thumbnails is generated by hooking into the wp_generate_attachment_metadata hook, which triggers when you upload a new file.

Unfortunately, the regenerate thumbnails plugin only loops through images, so it will not trigger thumbnail generation for PDFs. It would be useful to support the regenerate thumbnails plugin. I will check with the author to see if we can figure something out. However, I reckon that will take some time.

For now, you can do it manually with the following code snippet:

add_action('admin_init', function () {

    if (!isset($_GET['regenerate_pdf_thumbnails'])) {
        return;
    }

    $chunk_size = empty($_GET['regenerate_pdf_thumbnails_chunk_size']) ? -1
        : $_GET['regenerate_pdf_thumbnails_chunk_size'];

    // Get all attachments
    $posts = get_posts(array(
        'post_type' => 'attachment',
        'post_status' => 'any',
        'posts_per_page' => $chunk_size,
        'fields' => 'ids',
        'paged' => (int) $_GET['regenerate_pdf_thumbnails'],
        'meta_key' => 'PdfThumbnailsPlugin',
        'meta_compare' => 'NOT EXISTS'
    ));

    // Regenerate metadata (incl. thumbnails and pdf thumnails)
    foreach ($posts as $id) {
        $file = get_attached_file($id);
        $meta = wp_generate_attachment_metadata($id, $file);
        update_post_meta($id, $meta);
    }
});

With that you can use https://YOURSITE?regenerate_pdf_thumbnails to trigger the generation. To avoid PHP running for too long, and cancelling the operation, you can use:

Regenerate attachments 1-5:
https://YOURSITE/wp-admin/upload.php?regenerate_pdf_thumbnails=1&regenerate_pdf_thumbnails_chunk_size=5

Regenerate attachments 6-10:
https://YOURSITE/wp-admin/upload.php?regenerate_pdf_thumbnails=1&regenerate_pdf_thumbnails_chunk_size=5

And so on.

I forgot to update the version number in main plugin file, sorry. Should be up now.

Hi,

That’s not a bad idea, I released a new update (version 0.0.4) that will name thumbnails as you described, PDF_NAME-thumbnail. This will name all new uploads. If you would like to automatically name existing files, you can use get_post_thumbnail_id($pdf_attachment_id) to find the thumbnail.

I’m glad you like the plugin and would like to encourage you to click “Works” on the compability for WordPress 4.0, and to add a rating/review if you have the time.

Thanks.

Stian

No problem. I understand that the installation can be cumbersome the first time, extact steps depends on your system, I’m linking to some resources below. The general process is as follows:

1. Install ghostscript
2. Install imagemagick, compiled with ghostscript support
3. Install PHP extension for imagemagick (can use pecl)
4. Restart web server for changes to take effect

Debian / Ubuntu

sudo apt-get install ghostscript php5-imagick
sudo service apache2 restart

Windows

How to install imagemagick on windows 7

How to install, test, convert, resize PDF using ImageMagick, Ghostscript, Windows Vista/7 x64

OSX

Installing ImageMagick on Mac OSX for PHP and MAMP

Test installation

To verify that your system is ready to generate thumbnails:

1. Create a file named test.php in your web root with the following content:

   <?php
   phpinfo();

2. Open https://YOUR-SITE/test.php in your web browser
3. Search for “imagick” and verify that “ImageMagick supported formats” contains “PDF”.

Two weeks since last message, assuming issue was resolved.

The thumbnail is stored on the PDF attachment, is it possible that you are trying to get a thumbnail for a normal post?

An easy way to test if thumbnails are working is to add the code you posted to single-attachment.php and open a PDF-attachment to verify that thumbnail is shown.

You can also use get_the_post_thumbnail($pdf_attachment_id) if you know the attachment ID.

If this does not work, I need some more information to go on, viewing the entire template file in would be helpful.