Allow tooltip as value for descriptionDisplay

README.md

@@ -0,0 +1,42 @@
+# JSON Forms for Drupal
+
+JSON Forms for Drupal is an implementation of the [JSON Forms](
+https://jsonforms.io/) specification for Drupal.
+
+## Additional features and keywords
+
+In this implementation there are some custom features and keywords not
+specified in standard JSON Forms. (TODO: Not all additional possibilities are
+described here, yet.)
+
+### Description display
+
+The Keyword `descriptionDisplay` in Control options allows to specify the
+display of the description. Possible options:
+
+* `after`
+* `before`
+* `invisible`
+* `tooltip`
+
+The first three options are standard options available for the
+`#description_display` in Drupal.
+
+The option `tooltip` leads to an additional CSS class on the description
+element: `json-forms-description-tooltip`. This can be used to process it
+with another module to display the description as tooltip.
+
+With the module [Form Tips](https://www.drupal.org/project/formtips) it can
+be achieved with this CSS selector:
+
+```css
+:not(.json-forms-description-tooltip)
+```
+
+## Limitations
+
+Some things cannot be done with (standard) Drupal forms, e.g.
+[Rules](https://jsonforms.io/docs/uischema/rules/) cannot completely be mapped
+to [conditional form fields](https://www.drupal.org/docs/drupal-apis/form-api/conditional-form-fields).
+
+TODO: Describe all limitations.

composer.json

@@ -30,8 +30,9 @@
         "sort-packages": true,
         "allow-plugins": {
             "dealerdirect/phpcodesniffer-composer-installer": true,
-            "php-http/discovery": true,
-            "phpstan/extension-installer": true
+            "php-http/discovery": false,
+            "phpstan/extension-installer": false,
+            "tbachert/spi": false
         }
     },
     "require": {

json_forms.module

@@ -1 +1,24 @@
 <?php
+declare(strict_types=1);
+
+use Drupal\Core\Template\Attribute;
+
+function _json_forms_add_tooltip_css_class(array &$variables): void {
+  if ('tooltip' === ($variables['element']['#_json_forms_description_display'] ?? NULL)) {
+    /** @var \Drupal\Core\Template\Attribute|null $descriptionAttributes */
+    $descriptionAttributes = $variables['description']['attributes'] ?? NULL;
+    if (NULL !== $descriptionAttributes) {
+      // Add the CSS class "json-forms-description-tooltip" to the description
+      // element. This can be used to process the element with another module.
+      $descriptionAttributes->merge(new Attribute(['class' => ['json-forms-description-tooltip']]));
+    }
+  }
+}
+
+function json_forms_preprocess_form_element(array &$variables): void {
+  _json_forms_add_tooltip_css_class($variables);
+}
+
+function json_forms_preprocess_fieldset(array &$variables): void {
+  _json_forms_add_tooltip_css_class($variables);
+}

src/Form/Control/Util/BasicFormPropertiesFactory.php

@@ -24,6 +24,7 @@
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\json_forms\Form\Control\Callbacks\RecalculateCallback;
 use Drupal\json_forms\Form\Control\Rule\StatesArrayFactory;
+use Drupal\json_forms\Form\Util\DescriptionDisplayUtil;
 use Drupal\json_forms\JsonForms\Definition\Control\ControlDefinition;
 
 final class BasicFormPropertiesFactory {
@@ -48,20 +49,8 @@ public static function createBasicProperties(ControlDefinition $definition): arr
       $form['#description'] = $definition->getDescription();
     }
 
-    $form['#description_attributes']['class'][] = 'foo';
-    switch ($definition->getOptionsValue('descriptionDisplay')) {
-      case 'after':
-        $form['#description_display'] = 'after';
-        break;
-
-      case 'before':
-        $form['#description_display'] = 'before';
-        break;
-
-      case 'invisible':
-        $form['#description_display'] = 'invisible';
-        break;
-    }
+    // @phpstan-ignore argument.type
+    DescriptionDisplayUtil::handleDescriptionDisplay($form, $definition->getOptionsValue('descriptionDisplay'));
 
     if (NULL !== $definition->getOptionsValue('placeholder')) {
       $form['#attributes']['placeholder'] = $definition->getOptionsValue('placeholder');

src/Form/Layout/AbstractLayoutArrayFactory.php

@@ -26,6 +26,7 @@
 use Drupal\json_forms\Form\AbstractConcreteFormArrayFactory;
 use Drupal\json_forms\Form\Control\Rule\StatesArrayFactoryInterface;
 use Drupal\json_forms\Form\FormArrayFactoryInterface;
+use Drupal\json_forms\Form\Util\DescriptionDisplayUtil;
 use Drupal\json_forms\JsonForms\Definition\Control\ControlDefinition;
 use Drupal\json_forms\JsonForms\Definition\DefinitionInterface;
 use Drupal\json_forms\JsonForms\Definition\Layout\LayoutDefinition;
@@ -50,6 +51,9 @@ public function createFormArray(
     /** @var \Drupal\json_forms\JsonForms\Definition\Layout\LayoutDefinition $definition */
     $form = $this->createBasicFormArray($definition);
 
+    // @phpstan-ignore argument.type
+    DescriptionDisplayUtil::handleDescriptionDisplay($form, $definition->getOptionsValue('descriptionDisplay'));
+
     if (NULL !== $definition->getRule()) {
       $form['#states'] = $this->statesArrayFactory->createStatesArray($definition->getRule());
     }

src/Form/Util/DescriptionDisplayUtil.php

@@ -0,0 +1,50 @@
+<?php
+
+/*
+ * Copyright (C) 2024 SYSTOPIA GmbH
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace Drupal\json_forms\Form\Util;
+
+final class DescriptionDisplayUtil {
+
+  /**
+   * @phpstan-param array<string, mixed> $form
+   */
+  public static function handleDescriptionDisplay(array &$form, ?string $descriptionDisplay): void {
+    if (NULL !== $descriptionDisplay) {
+      // See module hooks.
+      $form['#_json_forms_description_display'] = $descriptionDisplay;
+
+      switch ($descriptionDisplay) {
+        case 'after':
+          $form['#description_display'] = 'after';
+          break;
+
+        case 'before':
+          $form['#description_display'] = 'before';
+          break;
+
+        case 'invisible':
+          $form['#description_display'] = 'invisible';
+          break;
+      }
+    }
+  }
+
+}