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libgdal.py
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libgdal.py
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from __future__ import unicode_literals
import logging
import os
import re
from ctypes import c_char_p, c_int, CDLL, CFUNCTYPE
from ctypes.util import find_library
from django.contrib.gis.gdal.error import OGRException
logger = logging.getLogger('django.contrib.gis')
# Custom library path set?
try:
from django.conf import settings
lib_path = settings.GDAL_LIBRARY_PATH
except (AttributeError, EnvironmentError, ImportError):
lib_path = None
if lib_path:
lib_names = None
elif os.name == 'nt':
# Windows NT shared libraries
lib_names = ['gdal19', 'gdal18', 'gdal17', 'gdal16', 'gdal15']
elif os.name == 'posix':
# *NIX library names.
lib_names = ['gdal', 'GDAL', 'gdal1.9.0', 'gdal1.8.0', 'gdal1.7.0',
'gdal1.6.0', 'gdal1.5.0']
else:
raise OGRException('Unsupported OS "%s"' % os.name)
# Using the ctypes `find_library` utility to find the
# path to the GDAL library from the list of library names.
if lib_names:
for lib_name in lib_names:
lib_path = find_library(lib_name)
if not lib_path is None: break
if lib_path is None:
raise OGRException('Could not find the GDAL library (tried "%s"). '
'Try setting GDAL_LIBRARY_PATH in your settings.' %
'", "'.join(lib_names))
# This loads the GDAL/OGR C library
lgdal = CDLL(lib_path)
# On Windows, the GDAL binaries have some OSR routines exported with
# STDCALL, while others are not. Thus, the library will also need to
# be loaded up as WinDLL for said OSR functions that require the
# different calling convention.
if os.name == 'nt':
from ctypes import WinDLL
lwingdal = WinDLL(lib_path)
def std_call(func):
"""
Returns the correct STDCALL function for certain OSR routines on Win32
platforms.
"""
if os.name == 'nt':
return lwingdal[func]
else:
return lgdal[func]
#### Version-information functions. ####
# Returns GDAL library version information with the given key.
_version_info = std_call('GDALVersionInfo')
_version_info.argtypes = [c_char_p]
_version_info.restype = c_char_p
def gdal_version():
"Returns only the GDAL version number information."
return _version_info(b'RELEASE_NAME')
def gdal_full_version():
"Returns the full GDAL version information."
return _version_info('')
version_regex = re.compile(r'^(?P<major>\d+)\.(?P<minor>\d+)(\.(?P<subminor>\d+))?')
def gdal_version_info():
ver = gdal_version().decode()
m = version_regex.match(ver)
if not m: raise OGRException('Could not parse GDAL version string "%s"' % ver)
return dict([(key, m.group(key)) for key in ('major', 'minor', 'subminor')])
_verinfo = gdal_version_info()
GDAL_MAJOR_VERSION = int(_verinfo['major'])
GDAL_MINOR_VERSION = int(_verinfo['minor'])
GDAL_SUBMINOR_VERSION = _verinfo['subminor'] and int(_verinfo['subminor'])
GDAL_VERSION = (GDAL_MAJOR_VERSION, GDAL_MINOR_VERSION, GDAL_SUBMINOR_VERSION)
del _verinfo
# Set library error handling so as errors are logged
CPLErrorHandler = CFUNCTYPE(None, c_int, c_int, c_char_p)
def err_handler(error_class, error_number, message):
logger.error('GDAL_ERROR %d: %s' % (error_number, message))
err_handler = CPLErrorHandler(err_handler)
def function(name, args, restype):
func = std_call(name)
func.argtypes = args
func.restype = restype
return func
set_error_handler = function('CPLSetErrorHandler', [CPLErrorHandler], CPLErrorHandler)
set_error_handler(err_handler)