class ImageEffectAddForm

class ImageEffectAddForm extends ImageEffectFormBase {
    
    /**
     * The image effect manager.
     *
     * @var \Drupal\image\ImageEffectManager
     */
    protected $effectManager;
    
    /**
     * Constructs a new ImageEffectAddForm.
     *
     * @param \Drupal\image\ImageEffectManager $effect_manager
     *   The image effect manager.
     */
    public function __construct(ImageEffectManager $effect_manager) {
        $this->effectManager = $effect_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container) {
        return new static($container->get('plugin.manager.image.effect'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state, ?ImageStyleInterface $image_style = NULL, $image_effect = NULL) {
        $form = parent::buildForm($form, $form_state, $image_style, $image_effect);
        $form['#title'] = $this->t('Add %label effect to style %style', [
            '%label' => $this->imageEffect
                ->label(),
            '%style' => $image_style->label(),
        ]);
        $form['actions']['submit']['#value'] = $this->t('Add effect');
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function prepareImageEffect($image_effect) {
        $image_effect = $this->effectManager
            ->createInstance($image_effect);
        // Set the initial weight so this effect comes last.
        $image_effect->setWeight(count($this->imageStyle
            ->getEffects()));
        return $image_effect;
    }

}