Internal Shortcode | [Post_Thumb]

• Description
• Usage
• Return
• Params
• Examples/Sample
• Source
• Additional Resources

Description

Adds the Image URL of the Post's Thumb/Featured Image, but can also grab an image from the Post's Content. However, using WP's featured image can also utilize the size parameters.

Usage

[post_thumb size="thumbnail" extract="none"]

Params

size

(string) (optional) Determines which image URL size should be added. Adding a custom size will only return the closest downsize that is available. Default: "thumbnail"

• thumbnail
• medium
• large
• full
• "xx, yy"

extract

(string) (Optional) Determines whether to add any images from the Post's Content. Default: "none"

• none - Displays the Featured Image. Doesn't attempt to grab images from post content.
• on - If no Featured Image is found, then will attempt to use an image URL from post content.
• force - Feature Image is ignored, and will add the first <img> URL in post content.

Return

(string) Image URL.

Examples/Sample

Example 1

[post_thumb]

Returns

http://example.com/wp-content/uploads/2017/01/image.jpg

Example 2

[post_thumb extract="none" size="full"]

Returns

http://example.com/wp-content/uploads/2017/01/image.jpg

Example 3

[post_thumb extract="force"]

Returns

http://example.com/image.jpg

Source

File: advanced-post-list/includes/class/apl_shortcodes.php

/**
 * Post Thumb Shortcode. 
 * 
 * Desc: Adds a Post Thumb/Featured Image URL associated with the post, but 
 * can also grab an image within WP_Post->post_content (extract=on/force). 
 * Image Sizes include (default) thumbnail, medium, large, full, 
 * and custom "XX, XX" (closest image size available).
 * 
 * Note: Post_Content Images are not resizable.
 * 
 * 1. If 'size' string is numeric, then convert 'size' to an array(xx, yy).
 * 2. Grab Featured Image from Post/Page w/ 'size'.
 * 3. If 'extract' is 'on' OR 'force', add to return the src URL in img tag 
 *    from $post->post_content.
 * 4. Return string.
 * 
 * @since 0.1.0
 * @version 0.3.0 - Added 'extract' attribute. 
 * @version 0.4.0 - Changed to Class function, and uses WP's built-in
 *                  functions for setting default attributes & do_shortcode().
 *                  Added Custom Size support.
 * 
 * @param array $atts {
 *      
 *      Shortcode Attributes. 
 *      
 *      @type string $size      Sets the image size used by WP's function. 
 *                              (thumbnail, medium, large, full, and 
 *                              custom "XX, XX"). 
 *      @type string $extract   Extract from post_content (none, on, & force). 
 * }
 * @return string Post Image URL.
 */
public function post_thumb($atts)
{
    //INIT
    $atts_value = shortcode_atts( array(
        'size'      => 'full',
        'extract'   => 'none'
    ), $atts, 'post_thumb');
    $return_str ='';
    
    //STEP 1
    if (is_numeric(substr($atts_value['size'], 0, 1)) && substr($atts_value['size'], 0, 1) != '0')
    {
        $atts_value['size'] = explode(',', $atts_value['size']);
        foreach ($atts_value['size'] as $key => $value)
        {
            $atts_value['size'][$key] = intval($value);
        }
    }
    
    //STEP 2
    if ( strtolower($atts_value['extract']) != "force" && current_theme_supports('post-thumbnails'))
    {
        $featured_image = wp_get_attachment_image_src(get_post_thumbnail_id($this->_post->ID), $atts_value['size']);
        if ($featured_image)
        {
            $return_str .= $featured_image[0];
        }
    }
    
    //EXTRACT/FALLBACK IMAGE (No Featured Image)
    //STEP 3
    if ( strtolower($atts_value['extract']) != 'none' && empty($return_str) )
    {
        //Parse and grab src="{}"
        preg_match_all('/src="([^"]+)"/', $this->_post->post_content, $matches);
        if (!empty($matches[1]))
        {
            //TODO ADD Offset? OR save for post_attachments
            $return_str .= $matches[1][0];
        }
    }
    
    //STEP 4
    return $return_str;
}

Additional Resources