1 # prerequisites imports 

     2 from ctypes import c_void_p

     3 from django.contrib.gis.gdal.error import OGRException

     4 from django.contrib.gis.gdal.prototypes.ds import \

     5     get_driver, get_driver_by_name, get_driver_count, get_driver_name, register_all

     6 

     7 # For more information, see the OGR C API source code:

     8 #  http://www.gdal.org/ogr/ogr__api_8h.html

     9 #

    10 # The OGR_Dr_* routines are relevant here.

    11 class Driver(object):

    12     "Wraps an OGR Data Source Driver."

    13 

    14     # Case-insensitive aliases for OGR Drivers.

    15     _alias = {'esri' : 'ESRI Shapefile',

    16               'shp' : 'ESRI Shapefile',

    17               'shape' : 'ESRI Shapefile',

    18               'tiger' : 'TIGER',

    19               'tiger/line' : 'TIGER',

    20               }

    21                 

    22     def __init__(self, dr_input):

    23         "Initializes an OGR driver on either a string or integer input."

    24 

    25         if isinstance(dr_input, basestring):

    26             # If a string name of the driver was passed in

    27             self._ptr = None # Initially NULL

    28             self._register()

    29 

    30             # Checking the alias dictionary (case-insensitive) to see if an alias

    31             #  exists for the given driver.

    32             if dr_input.lower() in self._alias:

    33                 name = self._alias[dr_input.lower()]

    34             else:

    35                 name = dr_input

    36 

    37             # Attempting to get the OGR driver by the string name.

    38             dr = get_driver_by_name(name)

    39         elif isinstance(dr_input, int):

    40             self._register()

    41             dr = get_driver(dr_input)

    42         elif isinstance(dr_input, c_void_p):

    43             dr = dr_input

    44         else:

    45             raise OGRException('Unrecognized input type for OGR Driver: %s' % str(type(dr_input)))

    46 

    47         # Making sure we get a valid pointer to the OGR Driver

    48         if not dr:

    49             raise OGRException('Could not initialize OGR Driver on input: %s' % str(dr_input))

    50         self._ptr = dr

    51 

    52     def __str__(self):

    53         "Returns the string name of the OGR Driver."

    54         return get_driver_name(self._ptr)

    55 

    56     def _register(self):

    57         "Attempts to register all the data source drivers."

    58         # Only register all if the driver count is 0 (or else all drivers

    59         # will be registered over and over again)

    60         if not self.driver_count: register_all()

    61                     

    62     # Driver properties

    63     @property

    64     def driver_count(self):

    65         "Returns the number of OGR data source drivers registered."

    66         return get_driver_count()