1 """

     2  This module houses the GEOS ctypes prototype functions for the 

     3  topological operations on geometries.

     4 """

     5 from ctypes import c_char_p, c_double, c_int

     6 from django.contrib.gis.geos.libgeos import lgeos, GEOM_PTR

     7 from django.contrib.gis.geos.prototypes.errcheck import check_geom, check_string

     8 

     9 def topology(func, *args):

    10     "For GEOS unary topology functions."

    11     argtypes = [GEOM_PTR]

    12     if args: argtypes += args

    13     func.argtypes = argtypes

    14     func.restype = GEOM_PTR

    15     func.errcheck = check_geom

    16     return func

    17 

    18 ### Topology Routines ###

    19 geos_boundary = topology(lgeos.GEOSBoundary)

    20 geos_buffer = topology(lgeos.GEOSBuffer, c_double, c_int)

    21 geos_centroid = topology(lgeos.GEOSGetCentroid)

    22 geos_convexhull = topology(lgeos.GEOSConvexHull)

    23 geos_difference = topology(lgeos.GEOSDifference, GEOM_PTR)

    24 geos_envelope = topology(lgeos.GEOSEnvelope)

    25 geos_intersection = topology(lgeos.GEOSIntersection, GEOM_PTR)

    26 geos_pointonsurface = topology(lgeos.GEOSPointOnSurface)

    27 geos_preservesimplify = topology(lgeos.GEOSTopologyPreserveSimplify, c_double)

    28 geos_simplify = topology(lgeos.GEOSSimplify, c_double)

    29 geos_symdifference = topology(lgeos.GEOSSymDifference, GEOM_PTR)

    30 geos_union = topology(lgeos.GEOSUnion, GEOM_PTR)

    31 

    32 # GEOSRelate returns a string, not a geometry.

    33 geos_relate = lgeos.GEOSRelate

    34 geos_relate.argtypes = [GEOM_PTR, GEOM_PTR]

    35 geos_relate.errcheck = check_string