| """ |
| This module is for the miscellaneous GEOS routines, particularly the |
| ones that return the area, distance, and length. |
| """ |
| from ctypes import c_int, c_double, POINTER |
| from django.contrib.gis.geos.libgeos import GEOM_PTR, GEOS_PREPARE |
| from django.contrib.gis.geos.prototypes.errcheck import check_dbl, check_string |
| from django.contrib.gis.geos.prototypes.geom import geos_char_p |
| from django.contrib.gis.geos.prototypes.threadsafe import GEOSFunc |
| |
| __all__ = ['geos_area', 'geos_distance', 'geos_length'] |
| |
| ### ctypes generator function ### |
| def dbl_from_geom(func, num_geom=1): |
| """ |
| Argument is a Geometry, return type is double that is passed |
| in by reference as the last argument. |
| """ |
| argtypes = [GEOM_PTR for i in xrange(num_geom)] |
| argtypes += [POINTER(c_double)] |
| func.argtypes = argtypes |
| func.restype = c_int # Status code returned |
| func.errcheck = check_dbl |
| return func |
| |
| ### ctypes prototypes ### |
| |
| # Area, distance, and length prototypes. |
| geos_area = dbl_from_geom(GEOSFunc('GEOSArea')) |
| geos_distance = dbl_from_geom(GEOSFunc('GEOSDistance'), num_geom=2) |
| geos_length = dbl_from_geom(GEOSFunc('GEOSLength')) |
| |
| # Validity reason; only in GEOS 3.1+ |
| if GEOS_PREPARE: |
| geos_isvalidreason = GEOSFunc('GEOSisValidReason') |
| geos_isvalidreason.argtypes = [GEOM_PTR] |
| geos_isvalidreason.restype = geos_char_p |
| geos_isvalidreason.errcheck = check_string |
| __all__.append('geos_isvalidreason') |
