ImageLazyLoadController.php

<?php

namespace Drupal\image_lazy_load_test\Controller;

use Drupal\Core\Controller\ControllerBase;

/**
 * The ImageLazyLoadController class.
 */
class ImageLazyLoadController extends ControllerBase {
    
    /**
     * Render an image using image theme.
     *
     * @return array
     *   The render array.
     */
    public function renderImage() {
        $images['with-dimensions'] = [
            '#theme' => 'image',
            '#uri' => '/core/themes/olivero/logo.svg',
            '#alt' => 'Image lazy load testing image',
            '#prefix' => '<div id="with-dimensions">',
            '#suffix' => '</div>',
            '#width' => '50%',
            '#height' => '50%',
        ];
        $images['without-dimensions'] = [
            '#theme' => 'image',
            '#uri' => '/core/themes/olivero/logo.svg',
            '#alt' => 'Image lazy load testing image without dimensions',
            '#prefix' => '<div id="without-dimensions">',
            '#suffix' => '</div>',
        ];
        $images['override-loading-attribute'] = [
            '#theme' => 'image',
            '#uri' => '/core/themes/olivero/logo.svg',
            '#alt' => 'Image lazy load test loading attribute can be overridden',
            '#prefix' => '<div id="override-loading-attribute">',
            '#suffix' => '</div>',
            '#width' => '50%',
            '#height' => '50%',
        ];
        $images['override-loading-attribute']['#attributes']['loading'] = 'eager';
        return $images;
    }

}