Feature: #78450 - Introduce PreviewRenderer pattern

Pre-requisites

The PreviewRenderer usage is only active if the "fluid based page layout module" feature is enabled. This feature is activated by default in TYPO3 versions 10.3 and later.

The feature toggle can be located in the Settings admin module under Feature Toggles. Or it can be set in PHP using $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['fluidBasedPageModule'] = true; .

Description

A new pattern has been introduced to facilitate (record) previews in TYPO3. A default implementation has been added which provides support for the previous methods of generating previews (content previews - using hooks or by defining a Fluid template to render).

The new pattern creates a strict contract for code which generates such previews and enables switching out the implementation of both the resolving logic (which finds a preview renderer for a given table and record) as well as the rendering logic (which now renders both the actual preview and has contract methods for adding wrapping).

The main differences between the old and the new approach are:

• The class used to render previews is now defined in TCA and can be defined per-type or for any type.
• The resolver used to find preview renderers is a global implementation overridable in configuration.
• A single preview renderer will now be used. Before, hook subscribers had to toggle passed-by-reference flags.
• Wrapping is no longer forced to be a <span> tag so you are not restricted to inline and inline-block display.
• Preview renderers have a public contract which splits up actual preview and wrapping, allowing third party renderers to subclass the original renderer and for example only change the wrapping tag.
• Preview rendering can now be done ad-hoc. The pattern can be used from any context where the old pattern could only be used (was only used) in the PageLayoutView for content previews.

Impact

The feature adds two new concepts:

• PreviewRendererResolver which is a global implementation to detect which PreviewRenderer a given record needs.
• PreviewRenderer which is the class responsible for generating the preview and the wrapping.

$GLOBALS['TCA'][$table]['ctrl']['previewRenderer'] = My\PreviewRenderer::class;

$GLOBALS['TCA'][$table]['types'][$type]['previewRenderer'] = My\PreviewRenderer::class;

$GLOBALS['TCA'][$table]['types'][$type]['previewRenderer'][$subType] = My\PreviewRenderer::class;

/**
 * Dedicated method for rendering preview header HTML for
 * the page module only. Receives $item which is an instance of
 * GridColumnItem which has a getter method to return the record.
 *
 * @param GridColumnItem
 * @return string
 */
public function renderPageModulePreviewHeader(GridColumnItem $item);

/**
 * Dedicated method for rendering preview body HTML for
 * the page module only.
 *
 * @param GridColumnItem $item
 * @return string
 */
public function renderPageModulePreviewContent(GridColumnItem $item);

/**
 * Render a footer for the record to display in page module below
 * the body of the item's preview.
 *
 * @param GridColumnItem $item
 * @return string
 */
public function renderPageModulePreviewFooter(GridColumnItem $item): string;

/**
 * Dedicated method for wrapping a preview header and body HTML.
 *
 * @param string $previewHeader
 * @param string $previewContent
 * @param GridColumnItem $item
 * @return string
 */
public function wrapPageModulePreview($previewHeader, $previewContent, GridColumnItem $item);