Feature: #103211 - Introduce tree node labels

Description

We've upgraded the backend tree component by extending tree nodes to incorporate labels, offering enhanced functionality and additional information.

Before the implementation of labels, developers and integrators relied on pageTree.backgroundColor.<pageid> for visual cues, which has been deprecated with TYPO3 v13. However, these background colors lacked accessibility and meaningful context, catering only to users with perfect eyesight and excluding those dependent on screen readers or contrast modes.

With labels, we now cater to all editors. These labels not only offer customizable color markings for tree nodes but also require an associated label for improved accessibility.

Each node can support multiple labels, sorted by priority, with the highest priority label taking precedence over others. Users can assign a label to a node via user TSconfig, noting that only one label can be set through this method.

options.pageTree.label.<pageid> {
    label = Campaign A
    color = #ff8700
}

The labels can also be added by using the event \TYPO3\CMS\Backend\Controller\Event\AfterPageTreeItemsPreparedEvent .

<?php

declare(strict_types=1);

namespace MyVendor\MyExtension\Backend\EventListener;

use TYPO3\CMS\Backend\Controller\Event\AfterPageTreeItemsPreparedEvent;
use TYPO3\CMS\Backend\Dto\Tree\Label\Label;
use TYPO3\CMS\Core\Attribute\AsEventListener;

#[AsEventListener(
    identifier: 'my-extension/backend/modify-page-tree-items',
)]
final readonly class ModifyPageTreeItems
{
    public function __invoke(AfterPageTreeItemsPreparedEvent $event): void
    {
        $items = $event->getItems();
        foreach ($items as $item) {
            // Add special label for all pages with parent page ID 123
            if ($item['_page']['pid'] === 123) {
                $item['labels'][] = new Label(
                    label: 'Campaign B',
                    color: '#00658f',
                    priority: 1,
                );
            }
        }
        $event->setItems($items);
    }
}

Please note that only the marker for the label with the highest priority is rendered. All additional labels will only be added to the title of the node.

Impact

Labels are now added to the node and their children, significantly improving the clarity and accessibility of the tree component.