/django/contrib/gis/gdal/driver.py

 1# prerequisites imports 
 2from ctypes import c_void_p
 3from django.contrib.gis.gdal.base import GDALBase
 4from django.contrib.gis.gdal.error import OGRException
 5from 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.
11class 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()