Which fill algorithms do slicers use?

Hi,

I'm writing my own little slicer and am interested in how available slicers tackle the problem: I cut the model into slices and need to fill these slices/areas with lines, representing the moving path of the printer/nozzle. The problem is rather trivial for simple geometries without "islands" etc, but certainly not for complex geometries with smaller features, gaps etc. Unfortunately I cannot find any literature or anything on google, I'm really stuck here.

Further, it'd be nice to know how to apply rules to that fill algorithm, as they are common in available slicers, for example: use as many horizontal movements as possible or fill the contour in circles from the inside to the outside.

Any advice to get me started is highly appreciated.
Thanks so much!