public function GaussianBlurImageEffect::buildConfigurationForm in Image Effects 8

Same name and namespace in other branches

1. 8.3 src/Plugin/ImageEffect/GaussianBlurImageEffect.php \Drupal\image_effects\Plugin\ImageEffect\GaussianBlurImageEffect::buildConfigurationForm()
2. 8.2 src/Plugin/ImageEffect/GaussianBlurImageEffect.php \Drupal\image_effects\Plugin\ImageEffect\GaussianBlurImageEffect::buildConfigurationForm()

Form constructor.

Plugin forms are embedded in other forms. In order to know where the plugin form is located in the parent form, #parents and #array_parents must be known, but these are not available during the initial build phase. In order to have these properties available when building the plugin form's elements, let this method return a form element that has a #process callback and build the rest of the form in the callback. By the time the callback is executed, the element's #parents and #array_parents properties will have been set by the form API. For more documentation on #parents and #array_parents, see \Drupal\Core\Render\Element\FormElement.

Parameters

array $form: An associative array containing the initial structure of the plugin form.

\Drupal\Core\Form\FormStateInterface $form_state: The current state of the form. Calling code should pass on a subform state created through \Drupal\Core\Form\SubformState::createForSubform().

Return value

array The form structure.

Overrides PluginFormInterface::buildConfigurationForm

File

src/Plugin/ImageEffect/GaussianBlurImageEffect.php, line 43

Class

GaussianBlurImageEffect

Blur image using the Gaussian function.

Namespace

Drupal\image_effects\Plugin\ImageEffect

Code

public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
  $form['info'] = [
    '#type' => 'details',
    '#title' => $this
      ->t('Information'),
  ];
  $form['info']['help'] = [
    '#markup' => $this
      ->t("A Gaussian blur is generated by replacing each pixel's color values with the average of the surrounding pixels' colors. This region is a circle whose radius is given by the 'radius' argument. Thus, a larger 'radius' will yield a blurrier image. This average is not a simple mean of the values. Instead, values are weighted using the Gaussian function (roughly a bell curve centered around the destination pixel) giving it much more influence on the result than its neighbours. Thus, a fatter curve will give the center pixel more weight and make the image less  blurry; lower 'sigma' values will yield flatter curves."),
  ];
  $form['radius'] = [
    '#type' => 'number',
    '#title' => $this
      ->t('Radius'),
    '#description' => $this
      ->t('The radius of the blur, in pixels. <strong>The larger the radius, the slower the operation is.</strong> However, too small radius can lead to undesired aliasing effects.'),
    '#default_value' => $this->configuration['radius'],
    '#field_suffix' => $this
      ->t('px'),
    '#required' => TRUE,
    '#size' => 3,
    '#min' => 1,
    '#max' => 15,
  ];
  $form['sigma'] = [
    '#type' => 'number',
    '#title' => $this
      ->t('Sigma'),
    '#description' => $this
      ->t("Represents the 'fatness' of the Gaussian curve. Lower values mean less blurry image. Leave blank to use toolkit's default. As a guideline, 2/3 of the radius is a good starting point."),
    '#default_value' => $this->configuration['sigma'],
    '#required' => FALSE,
    '#size' => 5,
    '#min' => 0.1,
    '#max' => 15,
    '#step' => 0.1,
  ];
  return $form;
}