| """ |
| This module houses the GEOS ctypes prototype functions for the |
| topological operations on geometries. |
| """ |
| __all__ = ['geos_boundary', 'geos_buffer', 'geos_centroid', 'geos_convexhull', |
| 'geos_difference', 'geos_envelope', 'geos_intersection', |
| 'geos_linemerge', 'geos_pointonsurface', 'geos_preservesimplify', |
| 'geos_simplify', 'geos_symdifference', 'geos_union', 'geos_relate'] |
| |
| from ctypes import c_char_p, c_double, c_int |
| from django.contrib.gis.geos.libgeos import GEOM_PTR, GEOS_PREPARE |
| from django.contrib.gis.geos.prototypes.errcheck import check_geom, check_string |
| from django.contrib.gis.geos.prototypes.geom import geos_char_p |
| from django.contrib.gis.geos.prototypes.threadsafe import GEOSFunc |
| |
| def topology(func, *args): |
| "For GEOS unary topology functions." |
| argtypes = [GEOM_PTR] |
| if args: argtypes += args |
| func.argtypes = argtypes |
| func.restype = GEOM_PTR |
| func.errcheck = check_geom |
| return func |
| |
| ### Topology Routines ### |
| geos_boundary = topology(GEOSFunc('GEOSBoundary')) |
| geos_buffer = topology(GEOSFunc('GEOSBuffer'), c_double, c_int) |
| geos_centroid = topology(GEOSFunc('GEOSGetCentroid')) |
| geos_convexhull = topology(GEOSFunc('GEOSConvexHull')) |
| geos_difference = topology(GEOSFunc('GEOSDifference'), GEOM_PTR) |
| geos_envelope = topology(GEOSFunc('GEOSEnvelope')) |
| geos_intersection = topology(GEOSFunc('GEOSIntersection'), GEOM_PTR) |
| geos_linemerge = topology(GEOSFunc('GEOSLineMerge')) |
| geos_pointonsurface = topology(GEOSFunc('GEOSPointOnSurface')) |
| geos_preservesimplify = topology(GEOSFunc('GEOSTopologyPreserveSimplify'), c_double) |
| geos_simplify = topology(GEOSFunc('GEOSSimplify'), c_double) |
| geos_symdifference = topology(GEOSFunc('GEOSSymDifference'), GEOM_PTR) |
| geos_union = topology(GEOSFunc('GEOSUnion'), GEOM_PTR) |
| |
| # GEOSRelate returns a string, not a geometry. |
| geos_relate = GEOSFunc('GEOSRelate') |
| geos_relate.argtypes = [GEOM_PTR, GEOM_PTR] |
| geos_relate.restype = geos_char_p |
| geos_relate.errcheck = check_string |
| |
| # Routines only in GEOS 3.1+ |
| if GEOS_PREPARE: |
| geos_cascaded_union = GEOSFunc('GEOSUnionCascaded') |
| geos_cascaded_union.argtypes = [GEOM_PTR] |
| geos_cascaded_union.restype = GEOM_PTR |
| __all__.append('geos_cascaded_union') |
