def proj_obj(self):
     return EasyProjection(self.srs)
 def set_easy_srs(self, srs):
     self.srs = EasyProjection(srs).params()
 def lon_lat_layers_bounds(self):
     return self.layers_bounds().transform(self.proj_obj,
                                           EasyProjection(4326))
 def set_srs_by_srid(self, srid):
     self.srs = EasyProjection(srid).params()
 def lon_lat_bbox(self):
     return self.envelope().transform(self.proj_obj, EasyProjection(4326))