[TASK] Improve constants ViewHelper page

Documentation/Global/Constant.rst

@@ -1,7 +1,3 @@
-..  This reStructured text file has been automatically generated, do not change.
-..  Source: https://github.com/TYPO3/Fluid/blob/main/src/ViewHelpers/ConstantViewHelper.php
-
-:edit-on-github-link: https://github.com/TYPO3/Fluid/edit/main/src/ViewHelpers/ConstantViewHelper.php
 :navigation-title: constant
 
 ..  include:: /Includes.rst.txt
@@ -12,5 +8,72 @@
 Constant ViewHelper `<f:constant>`
 ==================================
 
+..  note::
+    The constant ViewHelper can display **PHP constants** only. It cannot be
+    used to display `TypoScript Constants <https://docs.typo3.org/permalink/t3tsref:typoscript-syntax-constants>`_
+    or `Site settings <https://docs.typo3.org/permalink/t3coreapi:sitehandling-settings>`_.
+
+..  typo3:viewhelper:: constant
+    :source: ../Global.json
+    :display: tags, description, gitHubLink
+    :noindex:
+
+..  contents:: Table of contents
+
+..  _typo3fluid-fluid-constant-global:
+
+Displaying global PHP constants in Fluid
+========================================
+
+You can display `global PHP constants <https://www.php.net/manual/en/reserved.constants.php>`_
+using this ViewHelper
+
+..  code-block:: html
+
+    Maximal possible number: {f:constant(name: 'PHP_INT_MAX')}
+
+    <f:if condition="{f:constant(name: 'PHP_MAJOR_VERSION')} >= 8">
+        Using PHP 8.0 or greater
+    </f:if>
+
+..  _typo3fluid-fluid-constant-class:
+
+Get class constant
+==================
+
+You can display any **public** class constant from a class within TYPO3,
+for example constants from :php:`\TYPO3\CMS\Core\Information\Typo3Information`:
+
+..  code-block:: html
+
+    Join the <f:link.external uri="{f:constant(name: '\TYPO3\CMS\Core\Information\Typo3Information::URL_COMMUNITY')}">
+        TYPO3 Community
+    </f:link.external>!
+
+..  _typo3fluid-fluid-constant-enum:
+
+Using enum cases in Fluid
+=========================
+
+Cases of enums are objects and not strings or integers. They cannot be directly
+output in the template. You can however save them into a variable and
+then use their value. For example you can use values of the enum cases in
+:php:`\TYPO3\CMS\Core\Resource\FileType` to compare them with a value of your
+object:
+
+..  code-block:: html
+
+    <f:variable name="imageType"><f:constant name="\TYPO3\CMS\Core\Resource\FileType::IMAGE"/></f:variable>
+    The image case has the value {imageType.value} and name {imageType.name}:
+    <f:if condition="{myFile.type} === {imageType.value}">
+        This file is an image!
+    </f:if>
+
+..  _typo3fluid-fluid-constant-arguments:
+
+Arguments
+=========
+
 ..  typo3:viewhelper:: constant
     :source: ../Global.json
+    :display: arguments-only