<p>This plugin will scan your thumbnail-less posts and look for a suitable image to use as a thumbnail.<br />
It will look for images linked in the post content and will download and add them to the local library.<br />
Post scanning is performed only when <code>the_post_thumbnail</code> or <code>get_the_post_thumbnail</code> are called for<br />
that particular post.</p>
<p>So you designed your new thumbnail-based template, but you have tons of thumbnail-less posts and<br />
don’t want to spend too much time on scraping your old posts for a thumbnail picture. Maybe you<br />
think you will probably forget to set a thumbnail for your new posts. Maybe both, as was my case :).</p>
<p>When a thumbnail for a post is queried and nothing is found this plugin will scrape the post for<br />
an <code><img></code> tag and its <code>href</code> property. Once a suitabile image is found (based on the configured<br />
settings), it will be downloaded ad set as the post thumbnail. If no suitable image is found,<br />
a default one will be used.</p>
<p>This plugin is still in early development state. It just covers my needs (see the “To do” section<br />
for more details). It has been tested only with wordpress 3.0.1, but should work also with 2.9,<br />
since I used similar code with 2.9 (even if it was included in my template’s <code>functions.php</code>).</p>
<p>The plugin is not supported. This doesn’t mean that I will not look into submitted bugs. Anyway,<br />
don’t expect prompt answers, since this is done in my spare time.</p>
<h3>To do</h3>
<p>Many things should be done in future releases. Here are some:</p>
<ul>
<li>Current version always downloads selected linked images. This works good with images hosted on external sites.<br />
If your posts link to images hosted in your media library, you will end up with two images.</li>
<li>A more user friendly name should be used for images added to the library (e.g. Thumbnail for post …)</li>
<li>Somewhere, a button to reset the “previously scanned” status of all posts should be provided (on current version,<br />
you cas set or reset it for single posts in the edit page.</li>
<li>“previously scanned” status should probably be reset (or at least you should be asked to) when publishing a<br />
updating an existing post</li>
</ul>
<p>More ideas are wellcome.</p>


Automatic Thumbnail Generator

Automated on-demand generation of posts thumbnails.

kubiq

<p>Generates thumbnail for PDF file automatically after file is uploaded to the Media library.</p>
<p>You can also generate thumbnails for old PDF files that are already in the Media library – you can generate missing thumbnails or regenerate all thumbnails.</p>
<p><strong>Imagick library must be installed on your server, otherwise this plugin will not work</strong></p>
<ul>
<li>automated test after plugin activation to make sure it will work on your server</li>
<li>works with all types of WordPress installations: domain, subdomain, subdirectory, multisite/network</li>
<li>works on Apache and NGiNX</li>
<li>automatically generate thumbnail for new uploaded PDFs</li>
<li>(re)generate thumbnails for existing PDFs in Media library</li>
<li>set maximum width of PDF thumbnail</li>
<li>set maximum height of PDF thumbnail</li>
<li>set image quality of PDF thumbnail</li>
<li>set image file type of PDF thumbnail</li>
</ul>
<h3>Shortcodes</h3>
<h3>pdf_thumbnail</h3>
<p>Maybe you want to display PDF thumbnail by using a shortcode</p>
<pre><code>[pdf_thumbnail id="123"]
</code></pre>
<h3>pdf_thumbnail_url</h3>
<p>Maybe you want to display PDF thumbnail url by using a shortcode</p>
<pre><code>[pdf_thumbnail_url id="123"]
</code></pre>
<h3>pdf_clickable_thumbnail</h3>
<p>Maybe you want to display clickable PDF thumbnail that will open PDF in new tab</p>
<pre><code>[pdf_clickable_thumbnail id="123"]
</code></pre>
<p> </p>
<h3>Functions</h3>
<h3>get_pdf_thumbnail_url</h3>
<p>If you want to return PDF thumbnail URL you can use</p>
<pre><code>get_pdf_thumbnail_url( $pdf_id )
</code></pre>
<p>it works similar to <code>wp_get_attachment_url</code> and it will return something like</p>
<pre><code>https://site.com/wp-content/uploads/2022/01/example.pdf.png
</code></pre>
<h3>get_pdf_thumbnail_path</h3>
<p>If you want to return PDF thumbnail URL you can use</p>
<pre><code>get_pdf_thumbnail_path( $pdf_id )
</code></pre>
<p>it works similar to <code>get_attached_file</code> and it will return something like</p>
<pre><code>/www/site.com/wp-content/uploads/2022/01/example.pdf.png
</code></pre>
<h3>get_pdf_thumbnail_image_src</h3>
<p>If you want to return PDF thumbnail url, width and height you can use</p>
<pre><code>get_pdf_thumbnail_image_src( $pdf_id )
</code></pre>
<p>it works similar to <code>wp_get_attachment_image_src</code> and it will return something like</p>
<pre><code>[
    0 => 'https://site.com/wp-content/uploads/2022/01/example.pdf.png',
    1 => 600,
    2 => 800
]
</code></pre>
<h3>get_pdf_thumbnail_image</h3>
<p>If you want to return PDF thumbnail image tag you can use</p>
<pre><code>get_pdf_thumbnail_image( $pdf_id )
</code></pre>
<p>it works similar to <code>wp_get_attachment_image</code> and it will return something like</p>
<pre><code><img src="https://site.com/wp-content/uploads/2022/01/example.pdf.png" width="600" height="800" alt="example" loading="lazy">
</code></pre>
<p> </p>
<h3>Hooks</h3>
<h3>pdf_thumbnail_max_width</h3>
<p>Maybe you want to change global PDF thumbnail max_width for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_max_width', function( $max_width, $pdf_id ){
    if( $pdf_id == 123 ){
        return 1024;
    }
    return $max_width;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_max_height</h3>
<p>Maybe you want to change global PDF thumbnail max_width for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_max_height', function( $max_height, $pdf_id ){
    if( $pdf_id == 123 ){
        return 768;
    }
    return $max_height;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_quality</h3>
<p>Maybe you want to change global PDF thumbnail quality for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_quality', function( $quality, $pdf_id ){
    if( $pdf_id == 123 ){
        return 100;
    }
    return $quality;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_type</h3>
<p>Maybe you want to change global PDF thumbnail file type for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_type', function( $type, $pdf_id ){
    if( $pdf_id == 123 ){
        return 'png'; // or 'jpg'
    }
    return $type;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_bgcolor</h3>
<p>Maybe you want to change default PDF thumbnail background for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_bgcolor', function( $bgcolor, $pdf_id ){
    if( $pdf_id == 123 ){
        return 'black'; // default is 'white'
    }
    return $bgcolor;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_page_number</h3>
<p>Maybe you want to PDF thumbnail page number for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_page_number', function( $page, $pdf_id ){
    if( $pdf_id == 123 ){
        return 1; // default is 0
    }
    return $page;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_filename</h3>
<p>Maybe you want to PDF thumbnail filename for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_filename', function( $filename, $pdf_id ){
    if( $pdf_id == 123 ){
        return str_replace( '.pdf.png', '.png', $filename );
    }
    return $filename;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_imagick</h3>
<p>Maybe you want to add watermark to PDF thumbnail for a specific PDF file</p>
<pre><code>add_filter( 'pdf_thumbnail_imagick', function( $imagick, $pdf_id ){
    if( $pdf_id == 123 ){
        // add your watermark here
    }
    return $imagick;
}, 10, 2 );
</code></pre>
<h3>get_pdf_thumbnail_image_attributes</h3>
<p>Maybe you want to change attributes for image tag from <code>get_pdf_thumbnail_image</code> function</p>
<pre><code>add_filter( 'get_pdf_thumbnail_image_attributes', function( $attr, $pdf_id ){
    $attr['loading'] = 'eager';
    return $attr;
}, 10, 2 );
</code></pre>
<h3>pdf_thumbnail_generated</h3>
<p>Maybe you want to do something after the thumbnail is generated</p>
<pre><code>add_action( 'pdf_thumbnail_generated', function( $thumbnail_path, $pdf_id ){
    // do somthing with the local file $thumbnail_path
}, 10, 2 );
</code></pre>


PDF Thumbnail Generator


I've used this on multiple sites and have found it invaluable.



While I've struggled with getting the required ImageMagick set up and working on a few servers – each one requiring a slightly different approach owing to different OS and security settings – this is not the fault of the plugin or plugin author.



I'm not sure what one reviewer means by this being built-in to WordPress; to the best of my knowledge that is incorrect.


Automatic Thumbnail Generator vs PDF Thumbnail Generator