1<?php
2
3namespace Drupal\Core\Render\Element;
4
5use Drupal\Core\Form\FormStateInterface;
6use Drupal\Core\Render\Element;
7
8/**
9 * Provides a slider for input of a number within a specific range.
10 *
11 * Provides an HTML5 input element with type of "range".
12 *
13 * Properties:
14 * - #min: Minimum value (defaults to 0).
15 * - #max: Maximum value (defaults to 100).
16 * Refer to \Drupal\Core\Render\Element\Number for additional properties.
17 *
18 * Usage example:
19 * @code
20 * $form['quantity'] = array(
21 *   '#type' => 'range',
22 *   '#title' => $this->t('Quantity'),
23 * );
24 * @endcode
25 *
26 * @see \Drupal\Core\Render\Element\Number
27 *
28 * @FormElement("range")
29 */
30class Range extends Number {
31
32  /**
33   * {@inheritdoc}
34   */
35  public function getInfo() {
36    $info = parent::getInfo();
37    $class = get_class($this);
38    return [
39      '#min' => 0,
40      '#max' => 100,
41      '#pre_render' => [
42        [$class, 'preRenderRange'],
43      ],
44      '#theme' => 'input__range',
45    ] + $info;
46  }
47
48  /**
49   * Prepares a #type 'range' render element for input.html.twig.
50   *
51   * @param array $element
52   *   An associative array containing the properties of the element.
53   *   Properties used: #title, #value, #description, #min, #max, #attributes,
54   *   #step.
55   *
56   * @return array
57   *   The $element with prepared variables ready for input.html.twig.
58   */
59  public static function preRenderRange($element) {
60    $element['#attributes']['type'] = 'range';
61    Element::setAttributes($element, ['id', 'name', 'value', 'step', 'min', 'max']);
62    static::setAttributes($element, ['form-range']);
63
64    return $element;
65  }
66
67  /**
68   * {@inheritdoc}
69   */
70  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
71    if ($input === '') {
72      $offset = ($element['#max'] - $element['#min']) / 2;
73
74      // Round to the step.
75      if (strtolower($element['#step']) != 'any') {
76        $steps = round($offset / $element['#step']);
77        $offset = $element['#step'] * $steps;
78      }
79
80      return $element['#min'] + $offset;
81    }
82  }
83
84}
85