listview icons load visible only, scroll to load next rows icons

[bish01]

Hi, I have a photo browser like script that shows listview with thumbnails of current directory.
Problem is that thumbnails are made for all files in a directory all at once then listview is shown.
Script is fast enough to display current dir but now I am making it show all subfolders as an option.
I can not show any example as that script is part of larger script and with my skill level it would take me days just to separate it to show and can not share whole script yet.

My question is is there a script example out somewhere that shows how to load only visible rows icons in listview and as you scroll down next set of rows icons would be created and displayed?
If not, would anyone share an idea on how I would go about making this? What do I have to think about when creating code, etc.
I hope this question makes sense.

Thanks for all help in advance.
Cheers