AjaxTestImageEffect.php

<?php

namespace Drupal\image_module_test\Plugin\ImageEffect;

use Drupal\Core\Ajax\AjaxResponse;
use Drupal\Core\Ajax\HtmlCommand;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Image\ImageInterface;
use Drupal\image\ConfigurableImageEffectBase;

/**
 * Provides a test effect using Ajax in the configuration form.
 *
 * @ImageEffect(
 *   id = "image_module_test_ajax",
 *   label = @Translation("Ajax test")
 * )
 */
class AjaxTestImageEffect extends ConfigurableImageEffectBase {
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        return [
            'test_parameter' => 0,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
        $form['test_parameter'] = [
            '#type' => 'number',
            '#title' => t('Test parameter'),
            '#default_value' => $this->configuration['test_parameter'],
            '#min' => 0,
        ];
        $form['ajax_refresh'] = [
            '#type' => 'button',
            '#value' => $this->t('Ajax refresh'),
            '#ajax' => [
                'callback' => [
                    $this,
                    'ajaxCallback',
                ],
            ],
        ];
        $form['ajax_value'] = [
            '#id' => 'ajax-value',
            '#type' => 'item',
            '#title' => $this->t('Ajax value'),
            '#markup' => 'bar',
        ];
        return $form;
    }
    
    /**
     * AJAX callback.
     */
    public function ajaxCallback($form, FormStateInterface $form_state) {
        $item = [
            '#type' => 'item',
            '#title' => $this->t('Ajax value'),
            '#markup' => microtime(),
        ];
        $response = new AjaxResponse();
        $response->addCommand(new HtmlCommand('#ajax-value', $item));
        return $response;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
        parent::submitConfigurationForm($form, $form_state);
        $this->configuration['test_parameter'] = $form_state->getValue('test_parameter');
    }
    
    /**
     * {@inheritdoc}
     */
    public function applyEffect(ImageInterface $image) {
        return TRUE;
    }

}