Here are some pictures of components of the langkas. The langkas are normally practiced in conjunction with the djurus. One typically does the first djuru, then the first step of the langka and so on until reaching the end of the djurus. Then the sequence is reversed from djuru eight to djuru one. The steps of the langka are reversed as well.
Sweeps become foot pulls, and sempok becomes depok.
As is the case with the djurus, langkas should not be thought of as sequences of set techniques. They are a vocabulary of movements which, when practiced with understanding, can be used in many different ways. If you don't mind waiting a while for images to load take a look at how one leg motion can be used in a variety of ways . Practice of the langkas and djurus together teaches the upper and lower body to work independently but in a coordinated fashion. The straight line is the first langka taught.