TestController.php

<?php

namespace Drupal\dialog_renderer_test\Controller;

use Drupal\Core\Url;

/**
 * Test controller display modal links and content.
 */
class TestController {
    
    /**
     * Return modal content.
     *
     * @return array
     *   Render array for display in modal.
     */
    public function modalContent() {
        return [
            '#type' => 'markup',
            '#markup' => 'Look at me in a modal!',
        ];
    }
    
    /**
     * Displays test links that will open in the modal dialog.
     *
     * @return array
     *   Render array with links.
     */
    public function linksDisplay() {
        return [
            'normal_modal' => [
                '#title' => 'Normal Modal!',
                '#type' => 'link',
                '#url' => Url::fromRoute('dialog_renderer_test.modal_content'),
                '#attributes' => [
                    'class' => [
                        'use-ajax',
                    ],
                    'data-dialog-type' => 'modal',
                ],
                '#attached' => [
                    'library' => [
                        'core/drupal.ajax',
                    ],
                ],
            ],
            'wide_modal' => [
                '#title' => 'Wide Modal!',
                '#type' => 'link',
                '#url' => Url::fromRoute('dialog_renderer_test.modal_content'),
                '#attributes' => [
                    'class' => [
                        'use-ajax',
                    ],
                    'data-dialog-type' => 'modal',
                    'data-dialog-renderer' => 'wide',
                ],
                '#attached' => [
                    'library' => [
                        'core/drupal.ajax',
                    ],
                ],
            ],
            'extra_wide_modal' => [
                '#title' => 'Extra Wide Modal!',
                '#type' => 'link',
                '#url' => Url::fromRoute('dialog_renderer_test.modal_content'),
                '#attributes' => [
                    'class' => [
                        'use-ajax',
                    ],
                    'data-dialog-type' => 'modal',
                    'data-dialog-renderer' => 'extra_wide',
                ],
                '#attached' => [
                    'library' => [
                        'core/drupal.ajax',
                    ],
                ],
            ],
        ];
    }

}