Editing Flood fill (section)

== Adding pattern filling support ==

Two common ways to make the span and pixel-based algorithms support pattern filling are either to use a unique color as a plain fill and then replace that with a pattern or to keep track (in a 2d Boolean array or as regions) of which pixels have been visited, using it to indicate pixels are no longer fillable. ''Inside'' must then return ''false'' for such visited pixels.<ref name="85Fishkin" />