[Neos] Adding additional data from PHP class in Page fluid template

[Pavlina Drosos]

Hi all!

I am implementing a custom page for images gallery, with title, description
and images. I decided to implement it like a separate layout page, which
extends the main layout page and the implementation is the same like the
Chapter element in the TYPO3.NeosDemoTypo3Org site. I did it this way
because I need a page to show all galleries and I implemented a Gallery
menu element, which is the same like the Chapter menu element.

I have added an additional property for the Gallery page in the inspector -
a tag. And now I want to fetch all images from the Media library, which
have this tag assigned and render them inside the Gallery page. And my
question is - where to implement this? Is it possible to add additional
variables to the fluid template of the Gallery page, which come from a PHP
class and can I see an example of this somewhere in Neos?

I know of course that I just can add a collection of image elements inside
the Gallery page, but the idea is to use the already uploaded images in the
media library easier.

Thank you in advance!

KR,
Pavlina