In C++ but fairly readable http://www.codeproject.com/gdi/QuickFill.asp
Also a good explanation of some of the simpler methods http://www.cs.unc.edu/~mcmillan/comp136/Lecture8/areaFills.html
Also a good explanation of some of the simpler methods http://www.cs.unc.edu/~mcmillan/comp136/Lecture8/areaFills.html