Kirki_Explode_Background_Field::explode PHP Method

        public static function explode($field)
        {
            $i18n = Kirki_l10n::get_strings($field['kirki_config']);
            $choices = self::background_choices();
            // Early exit if this is not a background field.
            if ('background' !== $field['type']) {
                return;
            }
            // No need to proceed any further if no defaults have been set.
            // We build the array of fields based on what default values have been defined.
            if (!isset($field['default']) || !is_array($field['default'])) {
                return;
            }
            $fields = array();
            $i = 0;
            foreach ($field['default'] as $key => $value) {
                // No need to process the opacity, it is factored in the color control.
                if ('opacity' === $key) {
                    continue;
                }
                $key = esc_attr($key);
                $setting = $key;
                $tooltip = $field['tooltip'];
                $description = isset($i18n['background-' . $key]) ? $i18n['background-' . $key] : '';
                $output_property = 'background-' . $key;
                $label = 0 === $i ? $field['label'] : '';
                $type = 'select';
                $sanitize_callback = 'esc_attr';
                switch ($key) {
                    case 'color':
                        // Use 'color-alpha' instead of 'color' if default is an rgba value or if 'opacity' is set.
                        $type = false !== strpos($field['default']['color'], 'rgba') ? 'color-alpha' : 'color';
                        $type = isset($field['default']['opacity']) ? 'color-alpha' : $type;
                        if (isset($field['default']['opacity']) && false === strpos($value, 'rgb')) {
                            $value = Kirki_Color::get_rgba($value, $field['default']['opacity']);
                        }
                        $sanitize_callback = array('Kirki_Sanitize_Values', 'color');
                        break;
                    case 'image':
                        $type = 'image';
                        $sanitize_callback = 'esc_url_raw';
                        break;
                    case 'attach':
                        // Small hack so that background attachments properly work.
                        $output_property = 'background-attachment';
                        $description = $i18n['background-attachment'];
                        break;
                    default:
                        $tooltip = '';
                        break;
                }
                // If we're using options & option_name is set, then we need to modify the setting.
                if (isset($field['option_type']) && 'option' === $field['option_type'] && isset($field['option_name']) && !empty($field['option_name'])) {
                    $property_setting = str_replace(']', '', str_replace($field['option_name'] . '[', '', $field['settings']));
                    $property_setting = esc_attr($field['option_name']) . '[' . esc_attr($property_setting) . '_' . $setting . ']';
                } else {
                    $property_setting = esc_attr($field['settings']) . '_' . $setting;
                }
                // Build the field's output element.
                $output_element = $field['output'];
                if (!empty($field['output'])) {
                    if (is_array($field['output'])) {
                        if (isset($field['output']['element'])) {
                            $output_element = $field['output']['element'];
                        } elseif (isset($field['output'][0]) && isset($field['output'][0]['element'])) {
                            $output_element = $field['output'][0]['element'];
                        }
                    }
                }
                /**
                 * Build the field.
                 * We're merging with the original field here, so any extra properties are inherited.
                 */
                $fields[$property_setting] = array_merge($field, array('type' => $type, 'label' => $label, 'settings' => $property_setting, 'tooltip' => $tooltip, 'section' => $field['section'], 'priority' => $field['priority'], 'required' => $field['required'], 'description' => $description, 'default' => $value, 'id' => sanitize_key(str_replace('[', '-', str_replace(']', '', $property_setting))), 'choices' => isset($choices[$key]) ? $choices[$key] : array(), 'sanitize_callback' => $sanitize_callback, 'output' => !empty($field['output']) ? array(array('element' => $output_element, 'property' => $output_property)) : array()));
                $i++;
            }
            return $fields;
        }