class ElementInfoController

class ElementInfoController extends ControllerBase {
    
    /**
     * Element info manager service.
     *
     * @var \Drupal\Core\Render\ElementInfoManagerInterface
     */
    protected $elementInfo;
    
    /**
     * The dumper service.
     *
     * @var \Drupal\devel\DevelDumperManagerInterface
     */
    protected $dumper;
    
    /**
     * EventInfoController constructor.
     *
     * @param \Drupal\Core\Render\ElementInfoManagerInterface $element_info
     *   Element info manager service.
     * @param \Drupal\devel\DevelDumperManagerInterface $dumper
     *   The dumper service.
     */
    public function __construct(ElementInfoManagerInterface $element_info, DevelDumperManagerInterface $dumper) {
        $this->elementInfo = $element_info;
        $this->dumper = $dumper;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('element_info'), $container->get('devel.dumper'));
    }
    
    /**
     * Builds the element overview page.
     *
     * @return array
     *   A render array as expected by the renderer.
     */
    public function elementList() {
        $headers = [
            $this->t('Name'),
            $this->t('Provider'),
            $this->t('Class'),
            $this->t('Operations'),
        ];
        $rows = [];
        foreach ($this->elementInfo
            ->getDefinitions() as $element_type => $definition) {
            $row['name'] = [
                'data' => $element_type,
                'filter' => TRUE,
            ];
            $row['provider'] = [
                'data' => $definition['provider'],
                'filter' => TRUE,
            ];
            $row['class'] = [
                'data' => $definition['class'],
                'filter' => TRUE,
            ];
            $row['operations']['data'] = [
                '#type' => 'operations',
                '#links' => [
                    'devel' => [
                        'title' => $this->t('Devel'),
                        'url' => Url::fromRoute('devel.elements_page.detail', [
                            'element_name' => $element_type,
                        ]),
                        'attributes' => [
                            'class' => [
                                'use-ajax',
                            ],
                            'data-dialog-type' => 'modal',
                            'data-dialog-options' => Json::encode([
                                'width' => 700,
                                'minHeight' => 500,
                            ]),
                        ],
                    ],
                ],
            ];
            $rows[$element_type] = $row;
        }
        ksort($rows);
        $output['elements'] = [
            '#type' => 'devel_table_filter',
            '#filter_label' => $this->t('Search'),
            '#filter_placeholder' => $this->t('Enter element id, provider or class'),
            '#filter_description' => $this->t('Enter a part of the element id, provider or class to filter by.'),
            '#header' => $headers,
            '#rows' => $rows,
            '#empty' => $this->t('No elements found.'),
            '#sticky' => TRUE,
            '#attributes' => [
                'class' => [
                    'devel-element-list',
                ],
            ],
        ];
        return $output;
    }
    
    /**
     * Returns a render array representation of the element.
     *
     * @param string $element_name
     *   The name of the element to retrieve.
     *
     * @return array
     *   A render array containing the element.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\NotFoundHttpException
     *   If the requested element is not defined.
     */
    public function elementDetail($element_name) {
        if (!($element = $this->elementInfo
            ->getDefinition($element_name, FALSE))) {
            throw new NotFoundHttpException();
        }
        $element += $this->elementInfo
            ->getInfo($element_name);
        return $this->dumper
            ->exportAsRenderable($element, $element_name);
    }

}