lens deformation

I want to make an appli which load all of my pictures folder, and paint pictures in icone mode.
But I want to have a lens, wich zoom and deform the scene. My lens is a quad, but i don’t know how to adress texture coords to it, because more than one texture can be “under” the lens !

for an exemple with one texture,

Hi !

Can’t you create one big texture with all the icons instead of lots of small ones ?