"""Proxy for coordinates stored outside Shapely geometries
"""
from shapely.geos import lgeos
from shapely import wkb
EMPTY = wkb.deserialize('010700000000000000'.decode('hex'))
class CachingGeometryProxy(object):
context = None
factory = None
__geom__ = EMPTY
_gtag = None
def __init__(self, context):
self.context = context
@property
def _is_empty(self):
return self.__geom__ in [EMPTY, None]
def empty(self):
if not self._is_empty:
lgeos.GEOSGeom_destroy(self.__geom__)
self.__geom__ = EMPTY
@property
def _geom(self):
"""Keeps the GEOS geometry in synch with the context."""
def __setstate__(self, state):
self.empty()
self.__geom__ = wkb.deserialize(state)
ob._ndim = 2
return ob
def exceptNull(func):
"""Decorator which helps avoid GEOS operations on null pointers."""
@wraps(func)
def wrapper(*args, **kwargs):
if not args[0]._geom or args[0].is_empty:
raise ValueError("Null/empty geometry supports no operations")
return func(*args, **kwargs)
return wrapper
EMPTY = wkb.deserialize('010700000000000000'.decode('hex'))
class BaseGeometry(object):
"""
Provides GEOS spatial predicates and topological operations.
"""
# Attributes
# ----------
# __geom__ : c_void_p
# Cached ctypes pointer to GEOS geometry. Not to be accessed.
# _geom : c_void_p
# Property by which the GEOS geometry is accessed.
# __p__ : object
def __setstate__(self, state):
self.empty()
self.__geom__ = wkb.deserialize(state)
if lgeos.methods['has_z'](g):
ob._ndim = 3
else:
ob._ndim = 2
return ob
def exceptNull(func):
"""Decorator which helps avoid GEOS operations on null pointers."""
@wraps(func)
def wrapper(*args, **kwargs):
if not args[0]._geom or args[0].is_empty:
raise ValueError("Null/empty geometry supports no operations")
return func(*args, **kwargs)
return wrapper
EMPTY = wkb.deserialize(bytes.fromhex('010700000000000000'))
class BaseGeometry(object):
"""
Provides GEOS spatial predicates and topological operations.
"""
# Attributes
# ----------
# __geom__ : c_void_p
# Cached ctypes pointer to GEOS geometry. Not to be accessed.
# _geom : c_void_p
# Property by which the GEOS geometry is accessed.
# __p__ : object
# Parent (Shapely) geometry
