text: from django import forms
  from django.utils.deconstruct import deconstructible
  from django.utils.translation import ugettext_lazy as _
  
  
  @deconstructible
  class GeometrySizeValidator(object):
      """Field validator to limit geometries to a given area."""
      message = _('Max area exceeded.')
      code = 'invalid'
  
      def __init__(self, max_area, srid=None):
          self.max_area = max_area
          self.srid = srid
  
      def __call__(self, geom):
          if not geom:
              return
          if self.srid and geom.srid != self.srid:
              geom.transform(self.srid)
          if (getattr(geom, 'ogr', geom).dimension > 1 and
                  geom.area > self.max_area):
              raise forms.ValidationError(self.message, code=self.code)
  