app/django/contrib/gis/gdal/libgdal.py
author Lennard de Rijk <ljvderijk@gmail.com>
Sun, 01 Feb 2009 17:14:42 +0000
changeset 1157 76e2ed09661c
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Added status property to the user model. This is to accommodate the ability to exclude users from using the website. Note that since the access modules is currently undergoing some reconstruction changing the status will not actually effect the User yet. Patch by: Lennard de Rijk Reviewed by: to-be-reviewed

import os, sys
from ctypes import c_char_p, CDLL
from ctypes.util import find_library
from django.contrib.gis.gdal.error import OGRException

# 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 library
    lib_names = ['gdal15']
elif os.name == 'posix':
    # *NIX library names.
    lib_names = ['gdal', '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('RELEASE_NAME')

def gdal_full_version(): 
    "Returns the full GDAL version information."
    return _version_info('')

def gdal_release_date(date=False): 
    """
    Returns the release date in a string format, e.g, "2007/06/27".
    If the date keyword argument is set to True, a Python datetime object
    will be returned instead.
    """
    from datetime import date as date_type
    rel = _version_info('RELEASE_DATE')
    yy, mm, dd = map(int, (rel[0:4], rel[4:6], rel[6:8]))
    d = date_type(yy, mm, dd)
    if date: return d
    else: return d.strftime('%Y/%m/%d')