sxiv is an alternative to feh and qiv.

Its only dependencies besides xlib are imlib2, libexif and giflib. The primary goal for writing sxiv is to create an image viewer, which only has the most basic features required for fast image viewing (the ones I want). It has vi key bindings and works nicely with tiling window managers. Its code base should be kept small and clean to make it easy for you to dig into it and customize it for your needs.