1 # prerequisites imports 

     2 from ctypes import c_void_p

     3 from django.contrib.gis.gdal.base import GDALBase

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

     5 from django.contrib.gis.gdal.prototypes import ds as capi

     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(GDALBase):

    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._register()

    28 

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

    30             #  exists for the given driver.

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

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

    33             else:

    34                 name = dr_input

    35 

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

    37             dr = capi.get_driver_by_name(name)

    38         elif isinstance(dr_input, int):

    39             self._register()

    40             dr = capi.get_driver(dr_input)

    41         elif isinstance(dr_input, c_void_p):

    42             dr = dr_input

    43         else:

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

    45 

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

    47         if not dr:

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

    49         self.ptr = dr

    50 

    51     def __str__(self):

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

    53         return capi.get_driver_name(self.ptr)

    54 

    55     def _register(self):

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

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

    58         # will be registered over and over again)

    59         if not self.driver_count: capi.register_all()

    60                     

    61     # Driver properties

    62     @property

    63     def driver_count(self):

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

    65         return capi.get_driver_count()