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"""
This module houses the ctypes initialization procedures, as well
as the notice and error handler function callbacks (get called
when an error occurs in GEOS).
This module also houses GEOS Pointer utilities, including
get_pointer_arr(), and GEOM_PTR.
"""
import logging
import os
import re
from ctypes import c_char_p, Structure, CDLL, CFUNCTYPE, POINTER
from ctypes.util import find_library
from django.contrib.gis.geos.error import GEOSException
from django.core.exceptions import ImproperlyConfigured
logger = logging.getLogger('django.contrib.gis')
# Custom library path set?
try:
from django.conf import settings
lib_path = settings.GEOS_LIBRARY_PATH
except (AttributeError, EnvironmentError,
ImportError, ImproperlyConfigured):
lib_path = None
# Setting the appropriate names for the GEOS-C library.
if lib_path:
lib_names = None
elif os.name == 'nt':
# Windows NT libraries
lib_names = ['geos_c', 'libgeos_c-1']
elif os.name == 'posix':
# *NIX libraries
lib_names = ['geos_c', 'GEOS']
else:
raise ImportError('Unsupported OS "%s"' % os.name)
# Using the ctypes `find_library` utility to find the path to the GEOS
# shared library. This is better than manually specifying each library name
# and extension (e.g., libgeos_c.[so|so.1|dylib].).
if lib_names:
for lib_name in lib_names:
lib_path = find_library(lib_name)
if lib_path is not None:
break
# No GEOS library could be found.
if lib_path is None:
raise ImportError(
'Could not find the GEOS library (tried "%s"). '
'Try setting GEOS_LIBRARY_PATH in your settings.' %
'", "'.join(lib_names)
)
# Getting the GEOS C library. The C interface (CDLL) is used for
# both *NIX and Windows.
# See the GEOS C API source code for more details on the library function calls:
# http://geos.refractions.net/ro/doxygen_docs/html/geos__c_8h-source.html
lgeos = CDLL(lib_path)
# The notice and error handler C function callback definitions.
# Supposed to mimic the GEOS message handler (C below):
# typedef void (*GEOSMessageHandler)(const char *fmt, ...);
NOTICEFUNC = CFUNCTYPE(None, c_char_p, c_char_p)
def notice_h(fmt, lst):
fmt, lst = fmt.decode(), lst.decode()
try:
warn_msg = fmt % lst
except TypeError:
warn_msg = fmt
logger.warning('GEOS_NOTICE: %s\n' % warn_msg)
notice_h = NOTICEFUNC(notice_h)
ERRORFUNC = CFUNCTYPE(None, c_char_p, c_char_p)
def error_h(fmt, lst):
fmt, lst = fmt.decode(), lst.decode()
try:
err_msg = fmt % lst
except TypeError:
err_msg = fmt
logger.error('GEOS_ERROR: %s\n' % err_msg)
error_h = ERRORFUNC(error_h)
#### GEOS Geometry C data structures, and utility functions. ####
# Opaque GEOS geometry structures, used for GEOM_PTR and CS_PTR
class GEOSGeom_t(Structure):
pass
class GEOSPrepGeom_t(Structure):
pass
class GEOSCoordSeq_t(Structure):
pass
class GEOSContextHandle_t(Structure):
pass
# Pointers to opaque GEOS geometry structures.
GEOM_PTR = POINTER(GEOSGeom_t)
PREPGEOM_PTR = POINTER(GEOSPrepGeom_t)
CS_PTR = POINTER(GEOSCoordSeq_t)
CONTEXT_PTR = POINTER(GEOSContextHandle_t)
# Used specifically by the GEOSGeom_createPolygon and GEOSGeom_createCollection
# GEOS routines
def get_pointer_arr(n):
"Gets a ctypes pointer array (of length `n`) for GEOSGeom_t opaque pointer."
GeomArr = GEOM_PTR * n
return GeomArr()
# Returns the string version of the GEOS library. Have to set the restype
# explicitly to c_char_p to ensure compatibility across 32 and 64-bit platforms.
geos_version = lgeos.GEOSversion
geos_version.argtypes = None
geos_version.restype = c_char_p
# Regular expression should be able to parse version strings such as
# '3.0.0rc4-CAPI-1.3.3', '3.0.0-CAPI-1.4.1', '3.4.0dev-CAPI-1.8.0' or '3.4.0dev-CAPI-1.8.0 r0'
version_regex = re.compile(
r'^(?P<version>(?P<major>\d+)\.(?P<minor>\d+)\.(?P<subminor>\d+))'
r'((rc(?P<release_candidate>\d+))|dev)?-CAPI-(?P<capi_version>\d+\.\d+\.\d+)( r\d+)?$'
)
def geos_version_info():
"""
Returns a dictionary containing the various version metadata parsed from
the GEOS version string, including the version number, whether the version
is a release candidate (and what number release candidate), and the C API
version.
"""
ver = geos_version().decode()
m = version_regex.match(ver)
if not m:
raise GEOSException('Could not parse version info string "%s"' % ver)
return dict((key, m.group(key)) for key in (
'version', 'release_candidate', 'capi_version', 'major', 'minor', 'subminor'))
# Version numbers and whether or not prepared geometry support is available.
_verinfo = geos_version_info()
GEOS_MAJOR_VERSION = int(_verinfo['major'])
GEOS_MINOR_VERSION = int(_verinfo['minor'])
GEOS_SUBMINOR_VERSION = int(_verinfo['subminor'])
del _verinfo
GEOS_VERSION = (GEOS_MAJOR_VERSION, GEOS_MINOR_VERSION, GEOS_SUBMINOR_VERSION)
# Here we set up the prototypes for the initGEOS_r and finishGEOS_r
# routines. These functions aren't actually called until they are
# attached to a GEOS context handle -- this actually occurs in
# geos/prototypes/threadsafe.py.
lgeos.initGEOS_r.restype = CONTEXT_PTR
lgeos.finishGEOS_r.argtypes = [CONTEXT_PTR]
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