In loop-single.php when clicking on the photo, I created a preview using the modal of item-send-friend.php, but I do not know what line I should put in that file so that each time I click on the photo, I add the view to the visualization counter...

What is the visitor counter code?

I do not think there is function for that, in model check item.php for class that do it.

Then, in item.php which line is the one that activates the hits counter?

@alexandromt
oc-includes/osclass/model/item.php

Well, thank you, but now it would be necessary to know where to put it so that each time that item-send-friend.php is opened a visit to the visit counter is added ...

@alexandromt
You should try bit more....

ItemStats::newInstance()->increase('i_num_views', osc_item_id());