Gallery IDS and Captions: hide/show on a per ID basis

Gallery Image Captions - Hide/Show

I just recalled this caption toggle question, when I was writing this answer, so let me rewrite it a little bit to work for this question.

Let's introduce the caption_toggle attribute for the native gallery shortcode, that takes a comma separated string of bool values.

It's possible to hide the captions with CSS, but here we do it via PHP.

Example

Here are three usage examples:

[gallery caption_toggle="yes,yes,no" ids="321,132,123"]

[gallery caption_toggle="true,true,false" ids="321,132,123"]

[gallery caption_toggle="1,1,0" ids="321,132,123"]

how to control the visibility of each image caption in the gallery.

Demo Plugin

Here's the demo plugin for PHP 5.4+ to support this feature:

<?php
/** 
 * Plugin Name: Gallery Image Captions - Hide/Show On A Per Image Id Basis
 * Description: Support for the caption_toggle attribute for the native post gallery
 * Plugin URI:  https://wordpress.stackexchange.com/a/228863/26350
 * Version:     1.0.0
 */

namespace WPSE\Q219782;

class Main
{
    /**
     * @var boolean
     */
    private $active;

    /**
     * @var array
     */
    private $settings;    

   /**
    * Setup actions and filters
    */
    public function activate()
    {
       add_filter( 'shortcode_atts_gallery', [ $this, 'shortcode_atts_gallery' ],10,3);
       add_action( 'pre_get_posts',          [ $this, 'pre_get_posts' ] );
       add_filter( 'the_posts',              [ $this, 'the_posts' ] );      
    }   

   /**
    * Get the user input for the caption_toggle attribute
    */
   public function shortcode_atts_gallery( $out, $pair, $atts )
   {
       if( ! empty( $atts['caption_toggle'] ) ) 
       {
           $this->active = true;
           $this->settings = explode( ',', $atts['caption_toggle'] );
       }
        return $out;
    }

   /**
    * Don't suppress filters for the gallery posts query
    */
    public function pre_get_posts( \WP_Query $q )
    {
        if( $this->active )
            $q->set( 'suppress_filters', false );
    }

   /**
    * Show/Hide the image caption according to the user settings
    */
    public function the_posts( $posts )
    {
        if( $this->active )
        {
            foreach( $posts as $i => $post )
            {
                if(    isset( $this->settings[$i] ) 
                    && wp_validate_boolean( $this->settings[$i] )
                )
                    $post->post_excerpt = '';
            }
            $this->active = false;
        }
        return $posts;
    }   

} // end class


/**
 * Activate
 */
( new Main )->activate();

How to install: Copy this code into the /wp-content/plugins/galleries-with-caption-toggle/plugin.php file and activate the plugin in the wp-admin backend the usual way. Then add e.g. caption_toggle="yes,yes,no" to your gallery shortcode to control the image caption visibility.