class ResizeImageEffect

class ResizeImageEffect extends ConfigurableImageEffectBase {
    
    /**
     * {@inheritdoc}
     */
    public function applyEffect(ImageInterface $image) {
        if (!$image->resize($this->configuration['width'], $this->configuration['height'])) {
            $this->logger
                ->error('Image resize failed using the %toolkit toolkit on %path (%mimetype, %dimensions)', [
                '%toolkit' => $image->getToolkitId(),
                '%path' => $image->getSource(),
                '%mimetype' => $image->getMimeType(),
                '%dimensions' => $image->getWidth() . 'x' . $image->getHeight(),
            ]);
            return FALSE;
        }
        return TRUE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function transformDimensions(array &$dimensions, $uri) {
        // The new image will have the exact dimensions defined for the effect.
        $dimensions['width'] = $this->configuration['width'];
        $dimensions['height'] = $this->configuration['height'];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getSummary() {
        $summary = [
            '#theme' => 'image_resize_summary',
            '#data' => $this->configuration,
        ];
        $summary += parent::getSummary();
        return $summary;
    }
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        return [
            'width' => NULL,
            'height' => NULL,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
        $form['width'] = [
            '#type' => 'number',
            '#title' => $this->t('Width'),
            '#default_value' => $this->configuration['width'],
            '#field_suffix' => ' ' . $this->t('pixels'),
            '#required' => TRUE,
            '#min' => 1,
        ];
        $form['height'] = [
            '#type' => 'number',
            '#title' => $this->t('Height'),
            '#default_value' => $this->configuration['height'],
            '#field_suffix' => ' ' . $this->t('pixels'),
            '#required' => TRUE,
            '#min' => 1,
        ];
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
        parent::submitConfigurationForm($form, $form_state);
        $this->configuration['height'] = $form_state->getValue('height');
        $this->configuration['width'] = $form_state->getValue('width');
    }

}