This plugin generates a thumbnail everytime you upload a PDF attachment. Generated thumbnail is an image of the first page in uploaded document.
This plugin hooks into the media manager and generates a thumbnail everytime a
PDF is uploaded. Generated thumbnail is an image of the first page in the
uploaded document and is named PDFNAME-thumbnail
, where PDFNAME
is replaced
by uploaded document filename.
Generated thumbnails are equivalent to featured
images so that common thumbnail
functions like get_post_thumbnail_id()
can be used for PDF attachments. See
Post Thumbnails for information
on how you can use thumbnails efficiently.
Integration with the javascript media API is not yet implemented, therefore, you
may need to reload the page before you can see generated thumbnail after an
upload.
It is possible to display a thumbnail linking to an uploaded PDF using the [pdf_thumbnails_link]
shortcode. The following attributes are supported:
id
– Attachment ID (required)size
– Thumbnail size (optional)title
– Anchor title attribute (optional)target
– Anchor target attribute (optional)download
– Anchor download attribute (optional)Example 1: Display link to PDF with ID = 172 using default thumbnail size
[pdf_thumbnails_link id="172"]
Example 2: Display link to PDF with ID = 172 using thumbnail size (default 150×150)
[pdf_thumbnails_link id="172" size="thumbnail"]
Thanks to mirgcire for providing the first
version of the [pdf_thumbnails_link]
shortcode.
In most cases it should be sufficient to use built-in thumbnail functions from
the WordPress API (get_post_thumbnail
and similar). If you need to modify the
way thumbnails are generated, you can override image generation with
the pdf_thumbnails_generate_image_blob
filter.
Example 1: Increase resolution for all generated PDF thumbnails
// $blob is the current image blob (defaults to null, can be used for chaining) // $filename is the PDF filename add_action('pdf_thumbnails_generate_image_blob', function ($blob, $filename) { $imagick = new Imagick(); $imagick->setResolution(200,200); $imagick->readImage($filename); $imagick->setIteratorIndex(0); $imagick->setImageFormat('jpg'); return $imagick->getImageBlob(); }, 10, 2);
It is possible to modify generated thumbnail links using the pdf_thumbnails_link_shortcode
filter. The following attributes are available:
$html
– Generated HTML code to be displayed$attachmentId
– Sanitized ID of the PDF attachment$size
– Sanitized thumbnail size$atts
– Shortcode attributes (not sanitized)$content
– Shortcode content (not sanitized)Example 2: Wrap thumbnail link in figure and append caption
add_filter('pdf_thumbnails_link_shortcode', function ($html, $attachmentId, $size, $atts, $content) { return "<figure>$html <caption>Click to open image $attachmentId</caption></figure>"; }, 10, 5);
Add generated image to media browser after upload.
Outline of an implementation based on the javascript media API:
// New uploads wp.Uploader.queue.on('add', function (attachment) { if (attachment.subtype !== 'pdf') { return; } findThumbnailFor(attachment.ID).then(function (data) { // Add attachment thumbnail to browser var attachment = wp.media.model.Attachment.get(id) attachment.fetch().done(function () { wp.media.editor.open().state().get('library').add(generated attachment) }); }); });
Filter: ajax_query_attachments_args
PDF Thumbnails requires ImageMagick with GhostScript support. If you are lucky,
this is already installed on your system, otherwise, installation can be done
with the following steps:
Details may differ based on which operating system you are running, see
Support for
more resources and tips on how this can be done in Windows, Linux and OSX.
sudo apt-get install ghostscript php5-imagick sudo service apache2 restart
This plugin use semantic versioning, i.e. breaking changes
increase the MAJOR version.
pdf_thumbnails_link
shortcodepdf_thumbnails_link
shortcodepdf_thumbnails_link_shortcode
filterpdf_thumbnails_before_get_image_blob
hook with pdf_thumbnails_generate_image_blob
filterpdf_thumbnails_before_get_image_blob
hook