Feature: #108726 - Introduce Fluid f:render.contentArea ViewHelper

Description

Instead of using the <f:cObject> and <f:for> ViewHelpers to render content areas, the new <f:render.contentArea> ViewHelper can be used.

It allows rendering content areas while enabling other extensions to modify the output via PSR-14 EventListeners.

This is especially useful for adding debugging wrappers or additional HTML structure around content areas.

By default, the ViewHelper renders the content area as-is, but EventListeners can listen to the \TYPO3\CMS\Fluid\Event\ModifyRenderedContentAreaEvent and modify the output.

You need to use the PAGEVIEW config like this:

page = PAGE
page.10 = PAGEVIEW
page.10.paths.10 = EXT:my_site_package/Resources/Private/Templates/

MyPage.fluid.html

<f:render.contentArea contentArea="{content.left}"/>
or
{content.left -> f:render.contentArea()}

The ViewHelper also supports wrapping each content element with additional markup if combined with the <f:render.record> ViewHelper:

MyPage.fluid.html

<f:render.contentArea contentArea="{content.main}" recordAs="record">
    before {record.fullType}
    <f:render.record record="{record}" />
    after {record.fullType}
</f:render.contentArea>

Impact

Theme creators are encouraged to use the <f:render.contentArea> ViewHelper to allow other extensions to modify the output via EventListeners.