transition.php

См. документацию.

<?php
 
namespace Bitrix\Landing\Hook\Page;
 
use Bitrix\Landing\Field;
use Bitrix\Landing\Hook;
use Bitrix\Landing\Landing;
use Bitrix\Landing\Manager;
use Bitrix\Main\Localization\Loc;
use Bitrix\Main\Page\Asset;

class Transition extends Hook\Page
{
    protected const BASE_COLOR = '#fff';

    protected function getMap(): array
    {
        return [
            'COLOR' => new Field\Text('COLOR', [
                'title' => Loc::getMessage('LANDING_HOOK_TRANSITION_COLOR'),
            ]),
        ];
    }

    public function enabled(): bool
    {
        if ($this->issetCustomExec())
        {
            return true;
        }
 
        if ($this->isPage())
        {
            return false;
        }
 
        return true; //always enable on site to default value
    }

    public function exec(): void
    {
        if ($this->execCustom())
        {
            return;
        }
 
        $type = strtoupper(Landing::getSiteType());
        if ($type === 'KNOWLEDGE')
        {
            return;
        }
 
        $color = \htmlspecialcharsbx(trim($this->fields['COLOR']->getValue()));
        if (!$color)
        {
            $color = self::BASE_COLOR;
        }
        $this->addTransitionClass();
        $this->setTransition($color);
    }
 
    protected function setTransition($color): void
    {
        Asset::getInstance()->addString(
            '<style>
                    @keyframes page-transition {
                        0% {
                            opacity: 1;
                        }
                        100% {
                            opacity: 0;
                        }
                    }
                    body.landing-page-transition::after {
                        opacity: 1;
                        background: ' . $color . ';
                        animation: page-transition 2s 1s forwards;
                    }
                </style>'
        );
    }
 
    protected function addTransitionClass(): void
    {
        //add background on page load
        Manager::setPageView(
            'BodyClass',
            'landing-page-transition'
        );
    }
}