Tachyon image service helper class to extend the resized image data. https://github.com/humanmade/tachyon-plugin

class-tachyon-helper.php

<?php
/**
 * Tachyon image service helper class to extend the resized image data.
 *
 * @package tachyon-helper
 */

namespace Tachyon_Helper;

use Tachyon;

/**
 * Class Tachyon_Helper
 */
class Tachyon_Helper extends Tachyon {

	/**
	 * Class variables
	 *
	 * @var object
	 */
	private static $__instance = null;

	/**
	 * Singleton implementation
	 *
	 * @return object
	 */
	public static function instance() {
		if ( ! is_a( self::$__instance, __CLASS__ ) ) {
			$class = get_called_class();
			self::$__instance = new $class;
			self::$__instance->init();
		}

		return self::$__instance;
	}

	/**
	 * Silence is golden.
	 */
	private function __construct() {}

	/**
	 * Init helper.
	 */
	public function init() {

		// Disable automatic creation of intermediate image sizes.
		add_filter( 'intermediate_image_sizes', '__return_empty_array' );
		add_filter( 'intermediate_image_sizes_advanced', '__return_empty_array' );
		add_filter( 'fallback_intermediate_image_sizes', '__return_empty_array' );

		add_filter( 'wp_get_attachment_metadata', [ $this, 'maybe_inject_image_sizes' ], 20, 2 );
	}

	/**
	 * Inject image sizes to attachment metadata.
	 *
	 * @param array $data          Attachment metadata.
	 * @param int   $attachment_id Attachment's post ID.
	 *
	 * @return array Attachment metadata.
	 */
	public function maybe_inject_image_sizes( $data, $attachment_id ) {
		// Can't do much if data is empty.
		if ( empty( $data ) ) {
			return $data;
		}

		// Missing some critical data we need to determine sizes, so bail.
		if (
			! isset( $data['file'] )
			|| ! isset( $data['width'] )
			|| ! isset( $data['height'] )
		) {
			return $data;
		}

		static $cached_sizes = [];

		// Don't process image sizes that we already processed.
		if ( isset( $cached_sizes[ $attachment_id ] ) ) {
			$data['sizes'] = $cached_sizes[ $attachment_id ];
			return $data;
		}

		// Skip non-image attachments.
		$mime_type = get_post_mime_type( $attachment_id );
		$attachment_is_image = preg_match( '!^image/!', $mime_type );
		if ( 1 !== $attachment_is_image ) {
			return $data;
		}

		if ( ! isset( $data['sizes'] ) || ! is_array( $data['sizes'] ) ) {
			$data['sizes'] = [];
		}

		$sizes_already_exist = false === empty( $data['sizes'] );

		$registered_image_sizes = self::image_sizes();

		if ( is_array( $registered_image_sizes ) ) {
			$available_sizes = array_keys( $registered_image_sizes );
			$known_sizes     = array_keys( $data['sizes'] );
			$missing_sizes   = array_diff( $available_sizes, $known_sizes );

			// Do not need to process if there is no missing image size.
			if ( $sizes_already_exist && empty( $missing_sizes ) ) {
				return $data;
			}

			$new_sizes = [];

			foreach ( $missing_sizes as $size ) {
				$new_width          = (int) $registered_image_sizes[ $size ]['width'];
				$new_height         = (int) $registered_image_sizes[ $size ]['height'];
				$new_sizes[ $size ] = [
					'file'      => basename( $data['file'] ),
					'width'     => $new_width,
					'height'    => $new_height,
					'mime_type' => $mime_type,
				];
			}

			if ( ! empty( $new_sizes ) ) {
				$data['sizes'] = array_merge( $data['sizes'], $new_sizes );
			}
		}

		$cached_sizes[ $attachment_id ] = $data['sizes'];

		return $data;
	}
}