'Mostly hand off functionality to Mapnik.ImageProvider.renderArea()'

def renderArea(self, width, height, srs, xmin, ymin, xmax, ymax, zoom):

    if (self.mapnik is None):
        self.mapnik = mapnik.Map(0, 0)
        load_map(self.mapnik, str(self.mapfile), self.workdir, cache_dir=self.workdir)
    return ImageProvider.renderArea(self, width, height, srs, xmin, ymin, xmax, ymax, zoom)
