Version 1

[yaffs-website] / web / core / lib / Drupal / Core / Render / Element / Checkbox.php

diff --git a/web/core/lib/Drupal/Core/Render/Element/Checkbox.php b/web/core/lib/Drupal/Core/Render/Element/Checkbox.php
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+++ b/web/core/lib/Drupal/Core/Render/Element/Checkbox.php
@@ -0,0 +1,134 @@
+<?php
+
+namespace Drupal\Core\Render\Element;
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Render\Element;
+
+/**
+ * Provides a form element for a single checkbox.
+ *
+ * Properties:
+ * - #return_value: The value to return when the checkbox is checked.
+ *
+ * Usage example:
+ * @code
+ * $form['copy'] = array(
+ *   '#type' => 'checkbox',
+ *   '#title' => $this->t('Send me a copy'),
+ * );
+ * @endcode
+ *
+ * @see \Drupal\Core\Render\Element\Checkboxes
+ *
+ * @FormElement("checkbox")
+ */
+class Checkbox extends FormElement {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getInfo() {
+    $class = get_class($this);
+    return [
+      '#input' => TRUE,
+      '#return_value' => 1,
+      '#process' => [
+        [$class, 'processCheckbox'],
+        [$class, 'processAjaxForm'],
+        [$class, 'processGroup'],
+      ],
+      '#pre_render' => [
+        [$class, 'preRenderCheckbox'],
+        [$class, 'preRenderGroup'],
+      ],
+      '#theme' => 'input__checkbox',
+      '#theme_wrappers' => ['form_element'],
+      '#title_display' => 'after',
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
+    if ($input === FALSE) {
+      // Use #default_value as the default value of a checkbox, except change
+      // NULL to 0, because FormBuilder::handleInputElement() would otherwise
+      // replace NULL with empty string, but an empty string is a potentially
+      // valid value for a checked checkbox.
+      return isset($element['#default_value']) ? $element['#default_value'] : 0;
+    }
+    else {
+      // Checked checkboxes are submitted with a value (possibly '0' or ''):
+      // http://www.w3.org/TR/html401/interact/forms.html#successful-controls.
+      // For checked checkboxes, browsers submit the string version of
+      // #return_value, but we return the original #return_value. For unchecked
+      // checkboxes, browsers submit nothing at all, but
+      // FormBuilder::handleInputElement() detects this, and calls this
+      // function with $input=NULL. Returning NULL from a value callback means
+      // to use the default value, which is not what is wanted when an unchecked
+      // checkbox is submitted, so we use integer 0 as the value indicating an
+      // unchecked checkbox. Therefore, modules must not use integer 0 as a
+      // #return_value, as doing so results in the checkbox always being treated
+      // as unchecked. The string '0' is allowed for #return_value. The most
+      // common use-case for setting #return_value to either 0 or '0' is for the
+      // first option within a 0-indexed array of checkboxes, and for this,
+      // \Drupal\Core\Render\Element\Checkboxes::processCheckboxes() uses the
+      // string rather than the integer.
+      return isset($input) ? $element['#return_value'] : 0;
+    }
+  }
+
+  /**
+   * Prepares a #type 'checkbox' render element for input.html.twig.
+   *
+   * @param array $element
+   *   An associative array containing the properties of the element.
+   *   Properties used: #title, #value, #return_value, #description, #required,
+   *   #attributes, #checked.
+   *
+   * @return array
+   *   The $element with prepared variables ready for input.html.twig.
+   */
+  public static function preRenderCheckbox($element) {
+    $element['#attributes']['type'] = 'checkbox';
+    Element::setAttributes($element, ['id', 'name', '#return_value' => 'value']);
+
+    // Unchecked checkbox has #value of integer 0.
+    if (!empty($element['#checked'])) {
+      $element['#attributes']['checked'] = 'checked';
+    }
+    static::setAttributes($element, ['form-checkbox']);
+
+    return $element;
+  }
+
+  /**
+   * Sets the #checked property of a checkbox element.
+   */
+  public static function processCheckbox(&$element, FormStateInterface $form_state, &$complete_form) {
+    $value = $element['#value'];
+    $return_value = $element['#return_value'];
+    // On form submission, the #value of an available and enabled checked
+    // checkbox is #return_value, and the #value of an available and enabled
+    // unchecked checkbox is integer 0. On not submitted forms, and for
+    // checkboxes with #access=FALSE or #disabled=TRUE, the #value is
+    // #default_value (integer 0 if #default_value is NULL). Most of the time,
+    // a string comparison of #value and #return_value is sufficient for
+    // determining the "checked" state, but a value of TRUE always means checked
+    // (even if #return_value is 'foo'), and a value of FALSE or integer 0
+    // always means unchecked (even if #return_value is '' or '0').
+    if ($value === TRUE || $value === FALSE || $value === 0) {
+      $element['#checked'] = (bool) $value;
+    }
+    else {
+      // Compare as strings, so that 15 is not considered equal to '15foo', but
+      // 1 is considered equal to '1'. This cast does not imply that either
+      // #value or #return_value is expected to be a string.
+      $element['#checked'] = ((string) $value === (string) $return_value);
+    }
+    return $element;
+  }
+
+}