diff -r 000000000000 -r 0d40e90630ef web/lib/django/contrib/gis/models.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/web/lib/django/contrib/gis/models.py Wed Jan 20 00:34:04 2010 +0100 @@ -0,0 +1,233 @@ +""" + Imports the SpatialRefSys and GeometryColumns models dependent on the + spatial database backend. +""" +import re +from django.conf import settings + +# Checking for the presence of GDAL (needed for the SpatialReference object) +from django.contrib.gis.gdal import HAS_GDAL, PYTHON23 +if HAS_GDAL: + from django.contrib.gis.gdal import SpatialReference + +class SpatialRefSysMixin(object): + """ + The SpatialRefSysMixin is a class used by the database-dependent + SpatialRefSys objects to reduce redundnant code. + """ + # For pulling out the spheroid from the spatial reference string. This + # regular expression is used only if the user does not have GDAL installed. + # TODO: Flattening not used in all ellipsoids, could also be a minor axis, + # or 'b' parameter. + spheroid_regex = re.compile(r'.+SPHEROID\[\"(?P.+)\",(?P\d+(\.\d+)?),(?P\d{3}\.\d+),') + + # For pulling out the units on platforms w/o GDAL installed. + # TODO: Figure out how to pull out angular units of projected coordinate system and + # fix for LOCAL_CS types. GDAL should be highly recommended for performing + # distance queries. + units_regex = re.compile(r'.+UNIT ?\["(?P[\w \'\(\)]+)", ?(?P[\d\.]+)(,AUTHORITY\["(?P[\w \'\(\)]+)","(?P\d+)"\])?\]([\w ]+)?(,AUTHORITY\["(?P[\w \'\(\)]+)","(?P\d+)"\])?\]$') + + def srs(self): + """ + Returns a GDAL SpatialReference object, if GDAL is installed. + """ + if HAS_GDAL: + # TODO: Is caching really necessary here? Is complexity worth it? + if hasattr(self, '_srs'): + # Returning a clone of the cached SpatialReference object. + return self._srs.clone() + else: + # Attempting to cache a SpatialReference object. + + # Trying to get from WKT first. + try: + self._srs = SpatialReference(self.wkt) + return self.srs + except Exception, msg: + pass + + try: + self._srs = SpatialReference(self.proj4text) + return self.srs + except Exception, msg: + pass + + raise Exception('Could not get OSR SpatialReference from WKT: %s\nError:\n%s' % (self.wkt, msg)) + else: + raise Exception('GDAL is not installed.') + srs = property(srs) + + def ellipsoid(self): + """ + Returns a tuple of the ellipsoid parameters: + (semimajor axis, semiminor axis, and inverse flattening). + """ + if HAS_GDAL: + return self.srs.ellipsoid + else: + m = self.spheroid_regex.match(self.wkt) + if m: return (float(m.group('major')), float(m.group('flattening'))) + else: return None + ellipsoid = property(ellipsoid) + + def name(self): + "Returns the projection name." + return self.srs.name + name = property(name) + + def spheroid(self): + "Returns the spheroid name for this spatial reference." + return self.srs['spheroid'] + spheroid = property(spheroid) + + def datum(self): + "Returns the datum for this spatial reference." + return self.srs['datum'] + datum = property(datum) + + def projected(self): + "Is this Spatial Reference projected?" + if HAS_GDAL: + return self.srs.projected + else: + return self.wkt.startswith('PROJCS') + projected = property(projected) + + def local(self): + "Is this Spatial Reference local?" + if HAS_GDAL: + return self.srs.local + else: + return self.wkt.startswith('LOCAL_CS') + local = property(local) + + def geographic(self): + "Is this Spatial Reference geographic?" + if HAS_GDAL: + return self.srs.geographic + else: + return self.wkt.startswith('GEOGCS') + geographic = property(geographic) + + def linear_name(self): + "Returns the linear units name." + if HAS_GDAL: + return self.srs.linear_name + elif self.geographic: + return None + else: + m = self.units_regex.match(self.wkt) + return m.group('unit_name') + linear_name = property(linear_name) + + def linear_units(self): + "Returns the linear units." + if HAS_GDAL: + return self.srs.linear_units + elif self.geographic: + return None + else: + m = self.units_regex.match(self.wkt) + return m.group('unit') + linear_units = property(linear_units) + + def angular_name(self): + "Returns the name of the angular units." + if HAS_GDAL: + return self.srs.angular_name + elif self.projected: + return None + else: + m = self.units_regex.match(self.wkt) + return m.group('unit_name') + angular_name = property(angular_name) + + def angular_units(self): + "Returns the angular units." + if HAS_GDAL: + return self.srs.angular_units + elif self.projected: + return None + else: + m = self.units_regex.match(self.wkt) + return m.group('unit') + angular_units = property(angular_units) + + def units(self): + "Returns a tuple of the units and the name." + if self.projected or self.local: + return (self.linear_units, self.linear_name) + elif self.geographic: + return (self.angular_units, self.angular_name) + else: + return (None, None) + units = property(units) + + def get_units(cls, wkt): + """ + Class method used by GeometryField on initialization to + retrive the units on the given WKT, without having to use + any of the database fields. + """ + if HAS_GDAL: + return SpatialReference(wkt).units + else: + m = cls.units_regex.match(wkt) + return m.group('unit'), m.group('unit_name') + get_units = classmethod(get_units) + + def get_spheroid(cls, wkt, string=True): + """ + Class method used by GeometryField on initialization to + retrieve the `SPHEROID[..]` parameters from the given WKT. + """ + if HAS_GDAL: + srs = SpatialReference(wkt) + sphere_params = srs.ellipsoid + sphere_name = srs['spheroid'] + else: + m = cls.spheroid_regex.match(wkt) + if m: + sphere_params = (float(m.group('major')), float(m.group('flattening'))) + sphere_name = m.group('name') + else: + return None + + if not string: + return sphere_name, sphere_params + else: + # `string` parameter used to place in format acceptable by PostGIS + if len(sphere_params) == 3: + radius, flattening = sphere_params[0], sphere_params[2] + else: + radius, flattening = sphere_params + return 'SPHEROID["%s",%s,%s]' % (sphere_name, radius, flattening) + get_spheroid = classmethod(get_spheroid) + + def __unicode__(self): + """ + Returns the string representation. If GDAL is installed, + it will be 'pretty' OGC WKT. + """ + try: + return unicode(self.srs) + except: + return unicode(self.wkt) + +# Django test suite on 2.3 platforms will choke on code inside this +# conditional. +if not PYTHON23: + try: + # try/except'ing the importation of SpatialBackend. Have to fail + # silently because this module may be inadvertently invoked by + # non-GeoDjango users (e.g., when the Django test suite executes + # the models.py of all contrib apps). + from django.contrib.gis.db.backend import SpatialBackend + if SpatialBackend.mysql: raise Exception + + # Exposing the SpatialRefSys and GeometryColumns models. + class SpatialRefSys(SpatialBackend.SpatialRefSys, SpatialRefSysMixin): + pass + GeometryColumns = SpatialBackend.GeometryColumns + except: + pass